ACP - Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">     <html xmlns="https://www.w3.org/1999/xhtml" xml:lang="en" lang="en" class="no-js co-ui">  <head>  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta charset="utf-8" /> <meta name="viewport" content="width=device-width, initial-scale=1" /> <meta name="theme-color" content="#000000" /> <meta name="application-name" content="1" /> <meta name="msapplication-TileColor" content="#FFFFFF" /> <link rel="preconnect" crossorigin="" href="https://contentmanager.copernicus.org/" /><link rel="icon" size="16x16" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_16x16_.ico" type="image/x-icon" /><link rel="icon" size="24x24" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_24x24_.ico" type="image/x-icon" /><link rel="icon" size="32x32" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_32x32_.ico" type="image/x-icon" /><link rel="icon" size="48x48" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_48x48_.ico" type="image/x-icon" /><link rel="icon" size="64x64" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_64x64_.ico" type="image/x-icon" /><link rel="icon" size="228x228" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_228x228_.png" type="image/png-icon" /><link rel="icon" size="195x195" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_195x195_.png" type="image/png-icon" /><link rel="icon" size="196x196" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_196x196_.png" type="image/png-icon" /><link rel="icon" size="128x128" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_128x128_.png" type="image/png-icon" /><link rel="icon" size="96x96" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_96x96_.png" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="180x180" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_180x180_.png" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="120x120" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_120x120_.png" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="152x152" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_152x152_.png" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="76x76" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_76x76_.png" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="57x57" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_57x57_.ico" type="image/png-icon" /><link rel="apple-touch-icon-precomposed" size="144x144" href="https://www.atmospheric-chemistry-and-physics.net/favicon_copernicus_144x144_.png" type="image/png-icon" /><script type="text/javascript" src="https://cdn.copernicus.org/libraries/mustache/2.3.0/mustache.min.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/libraries/jquery/1.11.1/jquery.min.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/js/copernicus.min.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/apps/htmlgenerator/js/htmlgenerator-v2.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe.min.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe-ui-default.min.js"></script><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/dszparallexer/dzsparallaxer.css" /><script type="text/javascript" src="https://cdn.copernicus.org/libraries/dszparallexer/dzsparallaxer.js"></script><link rel="stylesheet" type="text/css" media="all" id="hasBootstrap" href="https://cdn.copernicus.org/libraries/bootstrap/current/css/bootstrap.min.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/bootstrap/current/css/bootstrap-media.min.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/bootstrap/current/css/bootstrap-grid.min.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/bootstrap/current/css/bootstrap-reboot.min.css" /><script type="text/javascript" src="https://cdn.copernicus.org/libraries/bootstrap/current/js/popper.js"></script><script type="text/javascript" src="https://cdn.copernicus.org/libraries/bootstrap/current/js/bootstrap.min.js"></script><link rel="preconnect" crossorigin="" href="https://cdn.copernicus.org/" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/unsemantic/unsemantic.min.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/libraries/photoswipe/4.1/dark-icon-skin/dark-icon-skin.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/css/copernicus-min.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/css/fontawesome.css" /><link rel="stylesheet" type="text/css" media="all" href="https://cdn.copernicus.org/fonts/FontAwesome/5.11.2_and_4.7.0/css/all.font.css" /><link rel="stylesheet" type="text/css" media="projection, handheld, screen, tty, tv, print" href="https://contentmanager.copernicus.org/237997/10/ssl" /><link rel="stylesheet" type="text/css" media="projection, handheld, screen, tty, tv, print" href="https://contentmanager.copernicus.org/2154804/10/ssl" /><link rel="stylesheet" type="text/css" media="print" href="https://contentmanager.copernicus.org/2154805/10/ssl" /><script src="https://contentmanager.copernicus.org/1672/10/ssl" type="text/javascript"> </script><script src="https://contentmanager.copernicus.org/1468/10/ssl" type="text/javascript"> </script><script src="https://contentmanager.copernicus.org/402/10/ssl" type="text/javascript"> </script><script src="https://contentmanager.copernicus.org/2154808/10/ssl" type="text/javascript"> </script><meta name="global_projectID" content="10" /><meta name="global_pageID" content="297" /><meta name="global_pageIdentifier" content="home" /><meta name="global_moBaseURL" content="https://meetingorganizer.copernicus.org/" /><meta name="global_projectShortcut" content="ACP" /><meta name="global_projectDomain" content="https://www.atmospheric-chemistry-and-physics.net/" /> <title>ACP - Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015</title> <meta name="data-non-mobile-optimized-message" content="" /><script id="networker"> window.isSafari = /^((?!chrome|android).)*safari/i.test(navigator.userAgent); /** * */ function createToastsFunctionality() { const toastsWrapper = $('<div>') .attr('aria-live', 'polite') .attr('aria-atomic', 'true') .addClass('toasts-notifications-wrapper'); $('body').append(toastsWrapper); } function isOS() { return [ 'iPad Simulator', 'iPhone Simulator', 'iPod Simulator', 'iPad', 'iPhone', 'iPod' ].includes(navigator.platform) || (navigator.userAgent.includes("Mac") && "ontouchend" in document) } /** * * @param notificationContent */ function addToast(notificationContent) { const toast = $('<div>').addClass('toast').attr('role', 'alert').attr('aria-live', 'assertive') .attr('aria-atomic', 'true').attr('data-autohide', 'false'); const toastHeader = $('<div>').addClass('toast-header'); const toastHeaderTitle = $('<strong>').addClass('mr-auto').html(notificationContent.title); const toastHeaderCloseButton = $('<button>').addClass('ml-2').addClass('mb-1').addClass('close').attr('type', 'button') .attr('data-dismiss', 'toast'); const toastHeaderCloseIcon = $('<span>').attr('aria-hidden', 'true').html('×'); let url = ''; if (notificationContent.hasOwnProperty('url')) { url = notificationContent.url; } else { url = 'https://networker.copernicus.org/my-network'; } const toastBody = $('<div>').addClass('toast-body').html('<a target="_blank" href="' + url + '">' + notificationContent.text + '</a>'); $(toastHeaderCloseButton).append(toastHeaderCloseIcon); $(toastHeader).append(toastHeaderTitle); $(toastHeader).append(toastHeaderCloseButton); $(toast).append(toastHeader); $(toast).append(toastBody); $('.toasts-notifications-wrapper').append(toast); $('.toast').toast('show'); } function coNetworker_sendUsersLocation(location, userHash, publicLabel, projectID, application) { if (templateHasBootstrap()) { createToastsFunctionality(); } userHash = userHash || 'null'; location = location || 'c_content_manager::getProjectTemplateMobileOpt'; publicLabel = publicLabel || ''; if (publicLabel === ''){ publicLabel = location; } if (userHash !== null && userHash.length > 5) { try { if(typeof window.ws === 'undefined' || window.ws === null || !window.ws) { window.ws = new WebSocket('wss://websockets.copernicus.org:8080'); } else { window.ws.close(1000); window.ws = new WebSocket('wss://websockets.copernicus.org:8080'); } const data = { 'type': 'status', 'action': 'start', 'data': { 'userIdentifier': userHash, 'projectID': projectID, 'coApp': application, 'location': location, 'publicLabel': publicLabel } }; if (window.ws === 1) { window.ws.send(JSON.stringify(data)); } else { window.ws.onopen = function (msg) { window.ws.send(JSON.stringify(data)); dispatchEvent(new CustomEvent('loadCommonNetworker')); }; window.ws.onmessage = function (event) { try { const data = JSON.parse(event.data); switch (data.type) { case 'notification': const pushNotificationData = data.data; if (pushNotificationData.hasOwnProperty('user') && pushNotificationData.user.length > 5 && pushNotificationData.user === userHash) { window.showPushNotification(pushNotificationData); } break; } } catch (e) { console.log(e); } } } } catch (e) { console.error(e); } } } window.showPushNotification = function (notificationContent) { showMessage(notificationContent); function showMessage(notificationContent){ if (templateHasBootstrap()) { showBootstrapModal(notificationContent); } } function showBootstrapModal(notificationContent) { const randomId = getRandomInt(100,999); let modal = $('<div>').addClass('modal').attr('id', 'modal-notification' + randomId); let modalDialog = $('<div>').addClass('modal-dialog'); let modalContent = $('<div>').addClass('modal-content'); let modalBody = $('<div>').addClass('modal-body'); let message = $('<div>').addClass('modal-push-message').html('<h3 class="mb-3">' + notificationContent.title + '</h3><p>' + notificationContent.text + '</p>'); let buttonsWrapper = $('<div>').addClass('row'); let buttonsWrapperCol = $('<div>').addClass('col-12').addClass('text-right'); let buttonCancel = $('<button>').addClass('btn').addClass('btn-danger').addClass('mr-2').html('Cancel') let buttonSuccess = $('<button>').addClass('btn').addClass('btn-success').html('OK') $(buttonsWrapper).append(buttonsWrapperCol); $(buttonsWrapperCol).append(buttonCancel); $(buttonsWrapperCol).append(buttonSuccess); $(modalBody).append(message).append(buttonsWrapper); $(modalContent).append(modalBody); $(modalDialog).append(modalContent); $(modal).append(modalDialog); $(buttonCancel).on('click', (event) => { event.preventDefault(); event.stopPropagation(); event.stopImmediatePropagation(); $(modal).modal('hide'); }); $(buttonSuccess).on('click', (event) => { event.preventDefault(); event.stopPropagation(); event.stopImmediatePropagation(); $(modal).modal('hide'); handleOnclickNotification(notificationContent); }); $(modal).modal('show'); setTimeout(() => { dispatchEvent(new CustomEvent('modalLoaded', {'detail': 'modal-notification' + randomId})); }, 1000); } window.addEventListener('modalLoaded', function (event) { setTimeout(() => { $('#' + event.detail).modal('hide'); }, 9000); }); function handleOnclickNotification(notificationContent) { if (notificationContent.hasOwnProperty('withConnect') && notificationContent.withConnect.length > 0) { acceptContactRequest(notificationContent); } if (notificationContent.hasOwnProperty('url')) { if (window.isSafari && isOS()) { window.location.href = notificationContent.url; } else { window.open(notificationContent.url, '_blank').focus(); } } else { if (window.isSafari && isOS()) { window.open('https://networker.copernicus.org/my-network', '_blank'); } else { window.open('https://networker.copernicus.org/my-network', '_blank').focus(); } } } /** * * @param notificationContent */ function acceptContactRequest(notificationContent) { const formData = new FormData(); formData.append('r', notificationContent.userFrom); formData.append('a', 'a'); $.ajax({ url: 'https://networker.copernicus.org/handle-request-job', type: 'POST', data: formData, processData: false, contentType: false, xhrFields: { withCredentials: true }, beforeSend: function () { $('.splash').fadeIn(); $('.lightbox').fadeIn(); } }) .done(function (dataResponse) { const data = JSON.parse(dataResponse); let text = 'Please consider joining the text chat now.'; window.sendPushNotification({ title: window.userDataCommonNetworker.name + ' aims to chat with you.', text: text, user: data.message.userIdentifier, url: notificationContent.url }); $('.splash').fadeOut(); $('.lightbox').fadeOut(); }) .fail(function (error) { $('.splash').fadeOut(); $('.lightbox').fadeOut(); }); } } function templateHasBootstrap() { const bootstrap = document.getElementById('hasBootstrap'); return bootstrap !== null && typeof bootstrap !== 'undefined'; } coNetworker_sendUsersLocation(); dispatchEvent(new CustomEvent('loadCommonNetworker')); function getRandomInt(min, max) { min = Math.ceil(min); max = Math.floor(max); return Math.floor(Math.random() * (max - min + 1)) + min; } </script> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/libraries/photoswipe/4.1/dark-icon-skin/dark-icon-skin.css"> <base href="/"> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/libraries/unsemantic/unsemantic.min.css"> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/libraries/jquery/1.11.1/ui/jquery-ui.min.css"> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/libraries/jquery/1.11.1/ui/jquery-ui-slider-pips.css"> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe.css"> <link rel="stylesheet" type="text/css" href="https://cdn.copernicus.org/apps/htmlgenerator/css/htmlgenerator.css?v=1"> <meta name="citation_fulltext_world_readable" content=""> <meta name="citation_publisher" content="Copernicus GmbH"/> <meta name="citation_title" content="Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015"/> <meta name="citation_abstract" content="<p><strong class="journal-contentHeaderColor">Abstract.</strong> We use 2010–2015 observations of atmospheric methane columns from the GOSAT satellite instrument in a global inverse analysis to improve estimates of methane emissions and their trends over the period, as well as the global concentration of tropospheric OH (the hydroxyl radical, methane's main sink) and its trend. Our inversion solves the Bayesian optimization problem analytically including closed-form characterization of errors. This allows us to (1) quantify the information content from the inversion towards optimizing methane emissions and its trends, (2) diagnose error correlations between constraints on emissions and OH concentrations, and (3) generate a large ensemble of solutions testing different assumptions in the inversion. We show how the analytical approach can be used, even when prior error standard deviation distributions are lognormal. Inversion results show large overestimates of Chinese coal emissions and Middle East oil and gas emissions in the EDGAR v4.3.2 inventory but little error in the United States where we use a new gridded version of the EPA national greenhouse gas inventory as prior estimate. Oil and gas emissions in the EDGAR v4.3.2 inventory show large differences with national totals reported to the United Nations Framework Convention on Climate Change (UNFCCC), and our inversion is generally more consistent with the UNFCCC data. The observed 2010–2015 growth in atmospheric methane is attributed mostly to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH trends is small in comparison. We find that the inversion provides strong independent constraints on global methane emissions (546&thinsp;Tg&thinsp;a<span class="inline-formula"><sup>−1</sup></span>) and global mean OH concentrations (atmospheric methane lifetime against oxidation by tropospheric OH of <span class="inline-formula">10.8±0.4</span> years), indicating that satellite observations of atmospheric methane could provide a proxy for OH concentrations in the future.</p>"/> <meta name="citation_publication_date" content="2019/06/12"/> <meta name="citation_online_date" content="2019/06/12"/> <meta name="citation_journal_title" content="Atmospheric Chemistry and Physics"/> <meta name="citation_volume" content="19"/> <meta name="citation_issue" content="11"/> <meta name="citation_issn" content="1680-7316"/> <meta name="citation_doi" content="https://doi.org/10.5194/acp-19-7859-2019"/> <meta name="citation_firstpage" content="7859"/> <meta name="citation_lastpage" content="7881"/> <meta name="citation_author" content="Maasakkers, Joannes D."/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author_institution" content="now at: SRON Netherlands Institute for Space Research, Utrecht, the Netherlands"/> <meta name="citation_author_orcid" content="0000-0001-8118-0311"> <meta name="citation_author_email" content="maasakkers@fas.harvard.edu"> <meta name="citation_author" content="Jacob, Daniel J."/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author" content="Sulprizio, Melissa P."/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author" content="Scarpelli, Tia R."/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author_orcid" content="0000-0001-5544-8732"> <meta name="citation_author" content="Nesser, Hannah"/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author_orcid" content="0000-0001-6778-037X"> <meta name="citation_author" content="Sheng, Jian-Xiong"/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author_orcid" content="0000-0002-8008-3883"> <meta name="citation_author" content="Zhang, Yuzhong"/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author_institution" content="Environmental Defense Fund, Washington, DC, USA"/> <meta name="citation_author_orcid" content="0000-0001-5431-5022"> <meta name="citation_author" content="Hersher, Monica"/> <meta name="citation_author_institution" content="Harvard University, Cambridge, MA, USA"/> <meta name="citation_author" content="Bloom, A. Anthony"/> <meta name="citation_author_institution" content="Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA"/> <meta name="citation_author" content="Bowman, Kevin W."/> <meta name="citation_author_institution" content="Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA"/> <meta name="citation_author_institution" content="Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, CA, USA"/> <meta name="citation_author_orcid" content="0000-0002-8659-1117"> <meta name="citation_author" content="Worden, John R."/> <meta name="citation_author_institution" content="Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA"/> <meta name="citation_author" content="Janssens-Maenhout, Greet"/> <meta name="citation_author_institution" content="European Commission Joint Research Centre, Ispra (VA), Italy"/> <meta name="citation_author_orcid" content="0000-0002-9335-0709"> <meta name="citation_author" content="Parker, Robert J."/> <meta name="citation_author_institution" content="Earth Observation Science, Department of Physics and Astronomy, University of Leicester, Leicester, UK"/> <meta name="citation_author_institution" content="Leicester Institute for Space and Earth Observation, University of Leicester, Leicester, UK"/> <meta name="citation_author_institution" content="NERC National Centre for Earth Observation, Leicester, UK"/> <meta name="citation_author_orcid" content="0000-0002-0801-0831"> <meta name="citation_reference" content="Alexe, M., Bergamaschi, P., Segers, A., Detmers, R., Butz, A., Hasekamp, O., Guerlet, S., Parker, R., Boesch, H., Frankenberg, C., Scheepmaker, R. A., Dlugokencky, E., Sweeney, C., Wofsy, S. C., and Kort, E. A.: Inverse modelling of CH4 emissions for 2010–2011 using different satellite retrieval products from GOSAT and SCIAMACHY, Atmos. Chem. Phys., 15, 113–133, https://doi.org/10.5194/acp-15-113-2015, 2015. a, b"> <meta name="citation_reference" content="Allan, W., Struthers, H., and Lowe, D.: Methane carbon isotope effects caused by atomic chlorine in the marine boundary layer: Global model results compared with Southern Hemisphere measurements, J. Geophys. Res.-Atmos., 112, D04306, https://doi.org/10.1029/2006JD007369, 2007. a"> <meta name="citation_reference" content="Alvarez, R. A., Zavala-Araiza, D., Lyon, D. R., Allen, D. T., Barkley, Z. R., Brandt, A. R., Davis, K. J., Herndon, S. C., Jacob, D. J., Karion, A., Kort, E. A., Lamb, B. K., Lauvaux, T., Maasakkers, J. D., Marchese, A. J., Omara, M., Pacala, S. W., Peischl, J., Robinson, A. L., Shepson, P. B., Sweeney, C., Townsend-Small, A., Wofsy, S. C., and Hamburg, S. P.: Assessment of methane emissions from the U.S. oil and gas supply chain, Science, 361, 186–188, https://doi.org/10.1126/science.aar7204, 2018. a"> <meta name="citation_reference" content="Bader, W., Bovy, B., Conway, S., Strong, K., Smale, D., Turner, A. J., Blumenstock, T., Boone, C., Collaud Coen, M., Coulon, A., Garcia, O., Griffith, D. W. T., Hase, F., Hausmann, P., Jones, N., Krummel, P., Murata, I., Morino, I., Nakajima, H., O'Doherty, S., Paton-Walsh, C., Robinson, J., Sandrin, R., Schneider, M., Servais, C., Sussmann, R., and Mahieu, E.: The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005, Atmos. Chem. Phys., 17, 2255–2277, https://doi.org/10.5194/acp-17-2255-2017, 2017. a"> <meta name="citation_reference" content="Bergamaschi, P., Frankenberg, C., Meirink, J. F., Krol, M., Dentener, F., Wagner, T., Platt, U., Kaplan, J. O., Körner, S., Heimann, M., Dlugokencky, E. J., and Goede, A.: Satellite chartography of atmospheric methane from SCIAMACHY on board ENVISAT: 2. Evaluation based on inverse model simulations, J. Geophys. Res.-Atmos., 112, D02304, https://doi.org/10.1029/2006JD007268, 2007. a"> <meta name="citation_reference" content="Bloom, A. A., Bowman, K. W., Lee, M., Turner, A. J., Schroeder, R., Worden, J. R., Weidner, R., McDonald, K. C., and Jacob, D. J.: A global wetland methane emissions and uncertainty dataset for atmospheric chemical transport models (WetCHARTs version 1.0), Geosci. Model Dev., 10, 2141–2156, https://doi.org/10.5194/gmd-10-2141-2017, 2017. a, b, c, d"> <meta name="citation_reference" content="Blumenstock, T., Hase, F., Schneider, M., Garcia, O. E., andv67 Sepulveda, E.: TCCON data from Izana (ES), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.izana01.R0/114929, 2014. a"> <meta name="citation_reference" content="Bosilovich, M. G., Lucchesi, R., and Suarez, M.: File Specification for MERRA-2. GMAO Office Note No. 9 (Version 1.1), 73 pp., available at: https://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf (last access: 27 April 2019), 2016. a"> <meta name="citation_reference" content="Brasseur, G. and Jacob, D.: Mathematical Modeling of Atmospheric Chemistry, Cambridge University Press, https://doi.org/10.1017/9781316544754, 2017. a"> <meta name="citation_reference" content="Buchwitz, M., Reuter, M., Schneising, O., Boesch, H., Guerlet, S., Dils, B., Aben, I., Armante, R., Bergamaschi, P., Blumenstock, T., Bovensmann, H., Brunner, D., Buchmann, B., Burrows, J. P., Butz, A., Chédin, A., Chevallier, F., Crevoisier, C. D., Deutscher, N. M., Frankenberg, C., Hase, F., Hasekamp, O. P., Heymann, J., Kaminski, T., Laeng, A., Lichtenberg, G., De Mazière, M., Noël, S., Notholt, J., Orphal, J., Popp, C., Parker, R., Scholze, M., Sussmann, R., Stiller, G. P., Warneke, T., Zehner, C., Bril, A., Crisp, D., Griffith, D. W. T., Kuze, A., O'Dell, C., Oshchepkov, S., Sherlock, V., Suto, H., Wennberg, P., Wunch, D., Yokota, T., and Yoshida, Y.: Comparison and quality assessment of near-surface-sensitive satellite-derived CO2 and CH4 global data sets, Remote Sens. Environ., 162, 344–362, 2015. a, b, c, d"> <meta name="citation_reference" content="Butz, A., Guerlet, S., Hasekamp, O., Schepers, D., Galli, A., Aben, I., Frankenberg, C., Hartmann, J.-M., Tran, H., and Kuze, A.: Toward accurate CO2 and CH4 observations from GOSAT, Geophys. Res. Lett., 38, L14812, https://doi.org/10.1029/2011GL047888, 2011. a, b"> <meta name="citation_reference" content="Calisesi, Y., Soebijanta, V. T., and van Oss Roeland: Regridding of remote soundings: Formulation and application to ozone profile comparison, J. Geophys. Res.-Atmos., 110, D23306, https://doi.org/10.1029/2005JD006122, 2005. a"> <meta name="citation_reference" content="Cressot, C., Chevallier, F., Bousquet, P., Crevoisier, C., Dlugokencky, E. J., Fortems-Cheiney, A., Frankenberg, C., Parker, R., Pison, I., Scheepmaker, R. A., Montzka, S. A., Krummel, P. B., Steele, L. P., and Langenfelds, R. L.: On the consistency between global and regional methane emissions inferred from SCIAMACHY, TANSO-FTS, IASI and surface measurements, Atmos. Chem. Phys., 14, 577–592, https://doi.org/10.5194/acp-14-577-2014, 2014. a"> <meta name="citation_reference" content="Darmenov, A. and da Silva, A.: The quick fire emissions dataset (QFED)–documentation of versions 2.1, 2.2 and 2.4, NASA Technical Report Series on Global Modeling and Data Assimilation, NASA TM-2013-104606, 32, 183 pp., 2013. a"> <meta name="citation_reference" content="De Mazière, M., Sha, M. K., Desmet, F., Hermans, C., Scolas, F., Kumps, N., Metzger, J.-M., Duflot, V., and Cammas, J.-P.: TCCON data from Reunion Island (RE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.reunion01.R0/1149288, 2014. a"> <meta name="citation_reference" content="Deutscher, N. M., Notholt, J., Messerschmidt, J., Weinzierl, C., Warneke, T., Petri, C., Grupe, P., and Katrynski, K.: TCCON data from Bialystok (PL), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.bialystok01.R1/1183984, 2014. a"> <meta name="citation_reference" content="Dlugokencky, E. J., Nisbet, E. G., Fisher, R., and Lowry, D.: Global atmospheric methane: budget, changes and dangers, Philos. T. R. Soc. S.-A, 369, 2058–2072, 2011. a"> <meta name="citation_reference" content="Dubey, M., Henderson, B., Green, D., Butterfield, Z., Keppel-Aleks, G., Allen, N., Blavier, J.-F., Roehl, C., Wunch, D., and Lindenmaier, R.: TCCON data from Manaus (BR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.manaus01.R0/1149274, 2014a. a"> <meta name="citation_reference" content="Dubey, M., Lindenmaier, R., Henderson, B., Green, D., Allen, N., Roehl, C., Blavier, J.-F., Butterfield, Z., Love, S., Hamelmann, J., and Wunch, D.: TCCON data from Four Corners (US), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.fourcorners01.R0/1149272, 2014b. a"> <meta name="citation_reference" content="EIA: Shapefile for sedimentary basin boundaries in Lower 48 States, available at: http://eia.gov/maps/map_data/SedimentaryBasins_US_EIA.zip (last access: 27 April 2019), 2016. a"> <meta name="citation_reference" content="Etiope, G.: Natural Gas Seepage: The Earth's Hydrocarbon Degassing, Springer, 2015. a"> <meta name="citation_reference" content="Etiope, G. and Klusman, R. W.: Microseepage in drylands: flux and implications in the global atmospheric source/sink budget of methane, Global Planet. Change, 72, 265–274, 2010. a"> <meta name="citation_reference" content="Franco, B., Mahieu, E., Emmons, L. K., Tzompa-Sosa, Z. A., Fischer, E. V., Sudo, K., Bovy, B., Conway, S., Griffin, D., Hannigan, J. W., Strong, K., and Walker, K. A.: Evaluating ethane and methane emissions associated with the development of oil and natural gas extraction in North America, Environ. Res. Lett., 11, 044010, https://doi.org/10.1088/1748-9326/11/4/044010, 2016. a"> <meta name="citation_reference" content="Fung, I., John, J., Lerner, J., Matthews, E., Prather, M., Steele, L., and Fraser, P.: Three-dimensional model synthesis of the global methane cycle, J. Geophys. Res.-Atmos., 96, 13033–13065, 1991. a, b"> <meta name="citation_reference" content="Ganesan, A. L., Rigby, M., Lunt, M. F., Parker, R. J., Boesch, H., Goulding, N., Umezawa, T., Zahn, A., Chatterjee, A., Prinn, R. G., Tiwari, Y. K., van der Schoot, M., and Krummel, P. B.: Atmospheric observations show accurate reporting and little growth in India's methane emissions, Nature Commun., 8, 836, https://doi.org/10.1038/s41467-017-00994-7, 2017. a"> <meta name="citation_reference" content="Griffith, D. W., Deutscher, N. M., Velazco, V. A., Wennberg, P. O., Yavin, Y., Aleks, G. K., Washenfelder, R. a., Toon, G. C., Blavier, J.-F., Murphy, C., Jones, N., Kettlewell, G., Connor, B. J., Macatangay, R., Roehl, C., Ryczek, M., Glowacki, J., Culgan, T., and Bryant, G.: TCCON data from Darwin (AU), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.darwin01.R0/1149290, 2014a. a"> <meta name="citation_reference" content="Griffith, D. W., Velazco, V. A., Deutscher, N. M., Murphy, C., Jones, N., Wilson, S., Macatangay, R., Kettlewell, G., Buchholz, R. R., and Riggenbach, M.: TCCON data from Wollongong (AU), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.wollongong01.R0/1149291, 2014b. a"> <meta name="citation_reference" content="Hartmann, D. L., Tank, A. M. K., Rusticucci, M., Alexander, L. V., Brönnimann, S., Charabi, Y. A. R., Dentener, F. J., Dlugokencky, E. J., Easterling, D. R., Kaplan, A., Soden, B. J., Thorne, P. W., Wild, M., and Zhai, P. M.: Observations: atmosphere and surface, in: Climate Change 2013 the Physical Science Basis: Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, 2013. a"> <meta name="citation_reference" content="Hase, F., Blumenstock, T., Dohe, S., Gross, J., and Kiel, M.: TCCON data from Karlsruhe (DE), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.karlsruhe01.R1/1182416, 2014. a"> <meta name="citation_reference" content="Hausmann, P., Sussmann, R., and Smale, D.: Contribution of oil and natural gas production to renewed increase in atmospheric methane (2007–2014): top–down estimate from ethane and methane column observations, Atmos. Chem. Phys., 16, 3227–3244, https://doi.org/10.5194/acp-16-3227-2016, 2016. a"> <meta name="citation_reference" content="Heald, C. L., Jacob, D. J., Jones, D., Palmer, P. I., Logan, J. A., Streets, D., Sachse, G. W., Gille, J. C., Hoffman, R. N., and Nehrkorn, T.: Comparative inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide, J. Geophys. Res.-Atmos., 109, D23306, https://doi.org/10.1029/2004JD005185, 2004. a"> <meta name="citation_reference" content="Holmes, C. D., Prather, M. J., Søvde, O. A., and Myhre, G.: Future methane, hydroxyl, and their uncertainties: key climate and emission parameters for future predictions, Atmos. Chem. Phys., 13, 285–302, https://doi.org/10.5194/acp-13-285-2013, 2013. a, b"> <meta name="citation_reference" content="Holmquist, J. R., Windham-Myers, L., Bliss, N., Crooks, S., Morris, J. T., Megonigal, J. P., Troxler, T., Weller, D., Callaway, J., Drexler, J., Ferner, M. C., Gonneea, M. E., Kroeger, K. D., Schile-Beers, L., Woo, I., Buffington, K., Breithaupt, J., Boyd, B. M., Brown, L. N., Dix, N., Hice, L., Horton, B. P., MacDonald, G. M., Moyer, R. P., Reay, W., Shaw, T., Smith, E., Smoak,<span id="page7878"/> J. M., Sommerfield, C., Thorne, K., Velinsky, D., Watson, E., Wilson Grimes, K., and Woodrey, M.: Accuracy and Precision of Tidal Wetland Soil Carbon Mapping in the Conterminous United States, Sci. Rep., 8, 9478, https://doi.org/10.1038/s41598-018-26948-7, 2018. a"> <meta name="citation_reference" content="Hossaini, R., Chipperfield, M. P., Saiz-Lopez, A., Fernandez, R., Monks, S., Feng, W., Brauer, P., and von Glasow, R.: A global model of tropospheric chlorine chemistry: Organic versus inorganic sources and impact on methane oxidation, J. Geophys. Res.-Atmos., 121, 14271–14297, https://doi.org/10.1002/2016JD025756, 2016. a"> <meta name="citation_reference" content="Houweling, S., Bergamaschi, P., Chevallier, F., Heimann, M., Kaminski, T., Krol, M., Michalak, A. M., and Patra, P.: Global inverse modeling of CH4 sources and sinks: an overview of methods, Atmos. Chem. Phys., 17, 235–256, https://doi.org/10.5194/acp-17-235-2017, 2017. a, b"> <meta name="citation_reference" content="IPCC: Guidelines for National Greenhouse Gas Inventories, in: The National Greenhouse Gas Inventories Programme, edited by: Eggleston, H. S., Buendia, L., Miwa, K., Ngara, T., and Tanabe, K., Hayama, Kanagawa, Japan, 2006. a"> <meta name="citation_reference" content="Iraci, L. T., Podolske, J., Hillyard, P. W., Roehl, C., Wennberg, P. O., Blavier, J.-F., Allen, N., Wunch, D., Osterman, G. B., and Albertson, R.: TCCON data from Edwards (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.edwards01.R1/1255068, 2016a. a"> <meta name="citation_reference" content="Iraci, L. T., Podolske, J., Hillyard, P. W., Roehl, C., Wennberg, P. O., Blavier, J.-F., Landeros, J., Allen, N., Wunch, D., Zavaleta, J., Quigley, E., Osterman, G. B., Barrow, E., and Barney, J.: TCCON data from Indianapolis (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.indianapolis01.R1/1330094, 2016b. a"> <meta name="citation_reference" content="Jacob, D. J., Turner, A. J., Maasakkers, J. D., Sheng, J., Sun, K., Liu, X., Chance, K., Aben, I., McKeever, J., and Frankenberg, C.: Satellite observations of atmospheric methane and their value for quantifying methane emissions, Atmos. Chem. Phys., 16, 14371–14396, https://doi.org/10.5194/acp-16-14371-2016, 2016. a, b"> <meta name="citation_reference" content="Janssens-Maenhout, G., Crippa, M., Guizzardi, D., Muntean, M., Schaaf, E., Dentener, F., Bergamaschi, P., Pagliari, V., Olivier, J., Peters, J., van Aardenne, J., Monni, S., Doering, U., Petrescu, R., Solazzo, E., and Oreggioni, G.: EDGAR v4.3.2 Global Atlas of the three major Greenhouse Gas Emissions for the period 1970–2012, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2018-164, in review, 2019. a, b"> <meta name="citation_reference" content="Kawakami, S., Ohyama, H., Arai, K., Okumura, H., Taura, C., Fukamachi, T., and Sakashita, M.: TCCON data from Saga (JP), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.saga01.R0/1149283, 2014. a"> <meta name="citation_reference" content="Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J. G., Dlugokencky, E. J., Bergamaschi, P., Bergmann, D., Blake, D. R., and Bruhwiler, L.: Three decades of global methane sources and sinks, Nat. Geosci., 6, 813–823, 2013. a, b, c"> <meta name="citation_reference" content="Kivi, R., Heikkinen, P., and Kyrö, E.: TCCON data from Sodankyla (FI), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.sodankyla01.R0/1149280, 2014. a"> <meta name="citation_reference" content="Kuze, A., Suto, H., Shiomi, K., Kawakami, S., Tanaka, M., Ueda, Y., Deguchi, A., Yoshida, J., Yamamoto, Y., Kataoka, F., Taylor, T. E., and Buijs, H. L.: Update on GOSAT TANSO-FTS performance, operations, and data products after more than 6 years in space, Atmos. Meas. Tech., 9, 2445–2461, https://doi.org/10.5194/amt-9-2445-2016, 2016. a, b"> <meta name="citation_reference" content="Kvenvolden, K. A. and Rogers, B. W.: Gaia's breath-global methane exhalations, Mar. Petrol. Geol., 22, 579–590, 2005. a, b"> <meta name="citation_reference" content="Larsen, K., Delgado, M., and Marsters, P.: Untapped potential: Reducing global methane emissions from oil and natural gas systems, Rhodium Group, LLC, New York, NY, USA, 2015. a"> <meta name="citation_reference" content="Lehner, B. and Döll, P.: Development and validation of a global database of lakes, reservoirs and wetlands, J. Hydrol., 296, 1–22, 2004. a"> <meta name="citation_reference" content="Liang, Q., Chipperfield, M. P., Fleming, E. L., Abraham, N. L., Braesicke, P., Burkholder, J. B., Daniel, J. S., Dhomse, S., Fraser, P. J., Hardiman, S. C., Jackman, C. H., Kinnison, D. E., Krummel, P. B., Montzka, S. A., Morgenstern, O., McCulloch, A., Mühle, J., Newman, P. A., Orkin, V. L., Pitari, G., Prinn, R. G., Rigby, M., Rozanov, E., Stenke, A., Tummon, F., Velders, G. J. M., Visioni, D., and Weiss, R. F.: Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CH3CCl3 Alternatives, J. Geophys. Res.-Atmos., 122, 11914–11933, https://doi.org/10.1002/2017JD026926, 2017. a"> <meta name="citation_reference" content="Lyon, D. R., Zavala-Araiza, D., Alvarez, R. A., Harriss, R., Palacios, V., Lan, X., Talbot, R., Lavoie, T., Shepson, P., and Yacovitch, T. I.: Constructing a spatially resolved methane emission inventory for the Barnett Shale region, Environ. Sci. Technol., 49, 8147–8157, 2015. a"> <meta name="citation_reference" content="Maasakkers, J. D., Jacob, D. J., Sulprizio, M. P., Turner, A. J., Weitz, M., Wirth, T., Hight, C., DeFigueiredo, M., Desai, M., and Schmeltz, R.: Gridded national inventory of US methane emissions, Environ. Sci. Technol., 50, 13123–13133, 2016. a, b, c, d, e, f"> <meta name="citation_reference" content="McNorton, J., Gloor, E., Wilson, C., Hayman, G. D., Gedney, N., Comyn-Platt, E., Marthews, T., Parker, R. J., Boesch, H., and Chipperfield, M. P.: Role of regional wetland emissions in atmospheric methane variability, Geophys. Res. Lett., 43, 11433–11444, https://doi.org/10.1002/2016GL070649, 2016. a, b"> <meta name="citation_reference" content="McNorton, J., Wilson, C., Gloor, M., Parker, R. J., Boesch, H., Feng, W., Hossaini, R., and Chipperfield, M. P.: Attribution of recent increases in atmospheric methane through 3-D inverse modelling, Atmos. Chem. Phys., 18, 18149–18168, https://doi.org/10.5194/acp-18-18149-2018, 2018. a"> <meta name="citation_reference" content="Miller, S. M., Wofsy, S. C., Michalak, A. M., Kort, E. A., Andrews, A. E., Biraud, S. C., Dlugokencky, E. J., Eluszkiewicz, J., Fischer, M. L., Janssens-Maenhout, G., Miller, B. R., Miller, J. B., Montzka, S. A., Nehrkorn, T., and Sweeney, C.: Anthropogenic emissions of methane in the United States, P. Natl. Acad. Sci. USA, 110, 20018–20022, https://doi.org/10.1073/pnas.1314392110, 2013. a"> <meta name="citation_reference" content="Miller, S. M., Michalak, A. M., and Levi, P. J.: Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions, Geosci. Model Dev., 7, 303–315, https://doi.org/10.5194/gmd-7-303-2014, 2014. a, b"> <meta name="citation_reference" content="Miller, S. M., Michalak, A. M., Detmers, R. G., Hasekamp, O. P., Bruhwiler, L. M., and Schwietzke, S.: China's coal mine methane regulations have not curbed growing emissions, Nat. Commun., 10, 303, https://doi.org/10.1038/s41467-018-07891-7, 2019. a, b, c, d"> <meta name="citation_reference" content="Monteil, G., Houweling, S., Butz, A., Guerlet, S., Schepers, D., Hasekamp, O., Frankenberg, C., Scheepmaker, R., Aben, I., and Röckmann, T.: Comparison of CH4 inversions based on 15 months of GOSAT and SCIAMACHY observations, J. Geophys. Res.-Atmos., 118, 11807–11823, https://doi.org/10.1002/2013JD019760, 2013. a, b"> <meta name="citation_reference" content="Morino, I., Matsuzaki, T., and Shishime, A.: TCCON data from Tsukuba (JP), 125HR, Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.tsukuba02.R1/1241486, 2014a. a"> <meta name="citation_reference" content="Morino, I., Yokozeki, N., Matzuzaki, T., and Horikawa, M.: TCCON data from Rikubetsu (JP), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.rikubetsu01.R1/1242265, 2014b. a"> <meta name="citation_reference" content="Murray, L. T., Jacob, D. J., Logan, J. A., Hudman, R. C., and Koshak, W. J.: Optimized regional and interannual variability of lightning in a global chemical transport model constrained by LIS/OTD satellite data, J. Geophys. Res.-Atmos., 117, D20307, https://doi.org/10.1029/2012JD017934, 2012. a"> <meta name="citation_reference" content="Naik, V., Voulgarakis, A., Fiore, A. M., Horowitz, L. W., Lamarque, J.-F., Lin, M., Prather, M. J., Young, P. J., Bergmann, D., Cameron-Smith, P. J., Cionni, I., Collins, W. J., Dalsøren, S. B., Doherty, R., Eyring, V., Faluvegi, G., Folberth, G. A., Josse, B., Lee, Y. H., MacKenzie, I. A., Nagashima, T., van Noije, T. P. C., Plummer, D. A., Righi, M., Rumbold, S. T., Skeie, R., Shindell, D. T., Stevenson, D. S., Strode, S., Sudo, K., Szopa, S., and Zeng, G.: Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Atmos. Chem. Phys., 13, 5277–5298, https://doi.org/10.5194/acp-13-5277-2013, 2013. a, b"> <meta name="citation_reference" content="Naus, S., Montzka, S. A., Pandey, S., Basu, S., Dlugokencky, E. J., and Krol, M.: Constraints and biases in a tropospheric two-box model of OH, Atmos. Chem. Phys., 19, 407–424, https://doi.org/10.5194/acp-19-407-2019, 2019. a"> <meta name="citation_reference" content="Nisbet, E., Dlugokencky, E., Manning, M., Lowry, D., Fisher, R., France, J., Michel, S., Miller, J., White, J., Vaughn, B., Bousquet, P., Pyle, J. A., Warwick, N. J., Cain, M., Brownlow, R., Zazzeri, G., Lanoisellé, M., Manning, A. C., Gloor, E., Worthy, D. E. J., Brunke, E.-G., Labuschagne, C., Wolff, E. W., and Ganesan, A. L.: Rising atmospheric methane: 2007–2014 growth and isotopic shift, Global Biogeochem. Cy., 30, 1356–1370, 2016. a, b"> <meta name="citation_reference" content="Notholt, J., Petri, C., Warneke, T., Deutscher, N. M., Buschmann, M., Weinzierl, C., Macatangay, R., and Grupe, P.: TCCON data from Bremen (DE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.bremen01.R0/1149275, 2014. a"> <meta name="citation_reference" content="Pandey, S., Houweling, S., Krol, M., Aben, I., Chevallier, F., Dlugokencky, E. J., Gatti, L. V., Gloor, E., Miller, J. B., Detmers, R., Machida, T., and Röckmann, T.: Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010, Atmos. Chem. Phys., 16, 5043–5062, https://doi.org/10.5194/acp-16-5043-2016, 2016. a, b"> <meta name="citation_reference" content="Pandey, S., Houweling, S., Krol, M., Aben, I., Monteil, G., Nechita-Banda, N., Dlugokencky, E. J., Detmers, R., Hasekamp, O., Xu, X., Riley, W. J., Poulter, B., Zhang, Z., McDonald, K. C., White, J. W. C., Bousquet, P., and Röckmann, T.: Enhanced methane emissions from tropical wetlands during the 2011 La Niña, Sci. Rep., 7, 45759, https://doi.org/10.1038/srep45759, 2017. a"> <meta name="citation_reference" content="Parker, R., Boesch, H., Cogan, A., Fraser, A., Feng, L., Palmer, P. I., Messerschmidt, J., Deutscher, N., Griffith, D. W., and Notholt, J.: Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations, Geophys. Res. Lett., 38, L15807, https://doi.org/10.1029/2011GL047871, 2011. a"> <meta name="citation_reference" content="Parker, R. J., Boesch, H., Byckling, K., Webb, A. J., Palmer, P. I., Feng, L., Bergamaschi, P., Chevallier, F., Notholt, J., Deutscher, N., Warneke, T., Hase, F., Sussmann, R., Kawakami, S., Kivi, R., Griffith, D. W. T., and Velazco, V.: Assessing 5 years of GOSAT Proxy XCH4 data and associated uncertainties, Atmos. Meas. Tech., 8, 4785–4801, https://doi.org/10.5194/amt-8-4785-2015, 2015. a, b, c, d"> <meta name="citation_reference" content="Patra, P. K., Houweling, S., Krol, M., Bousquet, P., Belikov, D., Bergmann, D., Bian, H., Cameron-Smith, P., Chipperfield, M. P., Corbin, K., Fortems-Cheiney, A., Fraser, A., Gloor, E., Hess, P., Ito, A., Kawa, S. R., Law, R. M., Loh, Z., Maksyutov, S., Meng, L., Palmer, P. I., Prinn, R. G., Rigby, M., Saito, R., and Wilson, C.: TransCom model simulations of CH4 and related species: linking transport, surface flux and chemical loss with CH4 variability in the troposphere and lower stratosphere, Atmos. Chem. Phys., 11, 12813–12837, https://doi.org/10.5194/acp-11-12813-2011, 2011. a"> <meta name="citation_reference" content="Peng, S., Piao, S., Bousquet, P., Ciais, P., Li, B., Lin, X., Tao, S., Wang, Z., Zhang, Y., and Zhou, F.: Inventory of anthropogenic methane emissions in mainland China from 1980 to 2010, Atmos. Chem. Phys., 16, 14545-14562, https://doi.org/10.5194/acp-16-14545-2016, 2016. a"> <meta name="citation_reference" content="Petrenko, V. V., Smith, A. M., Schaefer, H., Riedel, K., Brook, E., Baggenstos, D., Harth, C., Hua, Q., Buizert, C., Schilt, A., Fain, X., Mitchell, L., Bauska, T., Orsi, A., Weiss, R. F., and Severinghaus, J. P.: Minimal geological methane emissions during the Younger Dryas–Preboreal abrupt warming event, Nature, 548, 443–446, 2017. a"> <meta name="citation_reference" content="Prather, M. J., Holmes, C. D., and Hsu, J.: Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry, Geophys. Res. Lett., 39, L09803, https://doi.org/10.1029/2012GL051440, 2012. a, b, c, d, e"> <meta name="citation_reference" content="Ridgwell, A. J., Marshall, S. J., and Gregson, K.: Consumption of atmospheric methane by soils: A process-based model, Global Biogeochem. Cy., 13, 59–70, 1999. a"> <meta name="citation_reference" content="Rigby, M., Montzka, S. A., Prinn, R. G., White, J. W., Young, D., O'Doherty, S., Lunt, M. F., Ganesan, A. L., Manning, A. J., Simmonds, P. G., Salameh, P. K., Harth, C. M., Mühle, J., Weiss, R. F., Fraser, P. J., Steele, L. P., Krummel, P. B., McCulloch, A., and Park, S.: Role of atmospheric oxidation in recent methane growth, P. Natl. Acad. Sci. USA, 114, 5373–5377, 2017. a"> <meta name="citation_reference" content="Rodgers, C. D.: Inverse methods for atmospheric sounding: theory and practice, Series on Atmospheric Oceanic and Planetary Physics, vol. 2, World scientific, 256 pp., 2000. a, b, c, d, e"> <meta name="citation_reference" content="Saad, K. M., Wunch, D., Deutscher, N. M., Griffith, D. W. T., Hase, F., De Mazière, M., Notholt, J., Pollard, D. F., Roehl, C. M., Schneider, M., Sussmann, R., Warneke, T., and Wennberg,<span id="page7880"/> P. O.: Seasonal variability of stratospheric methane: implications for constraining tropospheric methane budgets using total column observations, Atmos. Chem. Phys., 16, 14003–14024, https://doi.org/10.5194/acp-16-14003-2016, 2016. a, b"> <meta name="citation_reference" content="Saunois, M., Bousquet, P., Poulter, B., Peregon, A., Ciais, P., Canadell, J. G., Dlugokencky, E. J., Etiope, G., Bastviken, D., Houweling, S., Janssens-Maenhout, G., Tubiello, F. N., Castaldi, S., Jackson, R. B., Alexe, M., Arora, V. K., Beerling, D. J., Bergamaschi, P., Blake, D. R., Brailsford, G., Brovkin, V., Bruhwiler, L., Crevoisier, C., Crill, P., Covey, K., Curry, C., Frankenberg, C., Gedney, N., Höglund-Isaksson, L., Ishizawa, M., Ito, A., Joos, F., Kim, H.-S., Kleinen, T., Krummel, P., Lamarque, J.-F., Langenfelds, R., Locatelli, R., Machida, T., Maksyutov, S., McDonald, K. C., Marshall, J., Melton, J. R., Morino, I., Naik, V., O'Doherty, S., Parmentier, F.-J. W., Patra, P. K., Peng, C., Peng, S., Peters, G. P., Pison, I., Prigent, C., Prinn, R., Ramonet, M., Riley, W. J., Saito, M., Santini, M., Schroeder, R., Simpson, I. J., Spahni, R., Steele, P., Takizawa, A., Thornton, B. F., Tian, H., Tohjima, Y., Viovy, N., Voulgarakis, A., van Weele, M., van der Werf, G. R., Weiss, R., Wiedinmyer, C., Wilton, D. J., Wiltshire, A., Worthy, D., Wunch, D., Xu, X., Yoshida, Y., Zhang, B., Zhang, Z., and Zhu, Q.: The global methane budget 2000–2012, Earth Syst. Sci. Data, 8, 697–751, https://doi.org/10.5194/essd-8-697-2016, 2016. a, b"> <meta name="citation_reference" content="Scarpelli, T., Jacob, D., Maasakkers, J. D., Sheng, J.-X., Rose, K., Sulprizio, M. P., and Worden, J.: A Global Gridded Inventory of Methane Emissions from Fuel Exploitation including Oil, Gas, and Coal, AGU 2018 Fall Meeting Abstract, 2018. a, b"> <meta name="citation_reference" content="Schaefer, H., Fletcher, S. E. M., Veidt, C., Lassey, K. R., Brailsford, G. W., Bromley, T. M., Dlugokencky, E. J., Michel, S. E., Miller, J. B., Levin, I., Lowe, D. C., Martin, R. J., Vaughn, B. H., and White, J. W. C.: A 21st-century shift from fossil-fuel to biogenic methane emissions indicated by 13CH4, Science, 352, 80–84, https://doi.org/10.1126/science.aad2705, 2016. a, b"> <meta name="citation_reference" content="Schwietzke, S., Sherwood, O. A., Bruhwiler, L. M., Miller, J. B., Etiope, G., Dlugokencky, E. J., Michel, S. E., Arling, V. A., Vaughn, B. H., White, J. W., and Tans, P. P.: Upward revision of global fossil fuel methane emissions based on isotope database, Nature, 538, 88–91, 2016. a, b"> <meta name="citation_reference" content="Sheng, J.-X., Jacob, D. J., Maasakkers, J. D., Sulprizio, M. P., Zavala-Araiza, D., and Hamburg, S. P.: A high-resolution (0.1∘×0.1∘) inventory of methane emissions from Canadian and Mexican oil and gas systems, Atmos. Environ., 158, 211–215, 2017. a"> <meta name="citation_reference" content="Sheng, J.-X., Jacob, D. J., Turner, A. J., Maasakkers, J. D., Benmergui, J., Bloom, A. A., Arndt, C., Gautam, R., Zavala-Araiza, D., Boesch, H., and Parker, R. J.: 2010–2016 methane trends over Canada, the United States, and Mexico observed by the GOSAT satellite: contributions from different source sectors, Atmos. Chem. Phys., 18, 12257–12267, https://doi.org/10.5194/acp-18-12257-2018, 2018a. a, b"> <meta name="citation_reference" content="Sheng, J.-X., Jacob, D. J., Turner, A. J., Maasakkers, J. D., Sulprizio, M. P., Bloom, A. A., Andrews, A. E., and Wunch, D.: High-resolution inversion of methane emissions in the Southeast US using SEAC4RS aircraft observations of atmospheric methane: anthropogenic and wetland sources, Atmos. Chem. Phys., 18, 6483–6491, https://doi.org/10.5194/acp-18-6483-2018, 2018b. a, b"> <meta name="citation_reference" content="Sherlock, V., Connor, B. J., Robinson, J., Shiona, H., Smale, D., and Pollard, D.: TCCON data from Lauder (NZ), 120HR, Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.lauder01.R0/1149293, 2014. a"> <meta name="citation_reference" content="Sherwen, T., Schmidt, J. A., Evans, M. J., Carpenter, L. J., Großmann, K., Eastham, S. D., Jacob, D. J., Dix, B., Koenig, T. K., Sinreich, R., Ortega, I., Volkamer, R., Saiz-Lopez, A., Prados-Roman, C., Mahajan, A. S., and Ordóñez, C.: Global impacts of tropospheric halogens (Cl, Br, I) on oxidants and composition in GEOS-Chem, Atmos. Chem. Phys., 16, 12239–12271, https://doi.org/10.5194/acp-16-12239-2016, 2016. a"> <meta name="citation_reference" content="Stanevich, I.: Variational data assimilation of satellite remote sensing observations for improving methane simulations in chemical transport models, PhD thesis, University of Toronto, 2018. a, b, c"> <meta name="citation_reference" content="Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M.: Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, 1535 pp., 2013. a"> <meta name="citation_reference" content="Strong, K., Mendonca, J., Weaver, D., Fogal, P., Drummond, J., Batchelor, R., and Lindenmaier, R.: TCCON data from Eureka (CA), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.eureka01.R1/1325515, 2017. a"> <meta name="citation_reference" content="Sussmann, R. and Rettinger, M.: TCCON data from Garmisch (DE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.garmisch01.R0/1149299, 2014. a"> <meta name="citation_reference" content="Te, Y., Jeseck, P., and Janssen, C.: TCCON data from Paris (FR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.paris01.R0/1149279, 2014. a"> <meta name="citation_reference" content="Thompson, R. L., Stohl, A., Zhou, L. X., Dlugokencky, E., Fukuyama, Y., Tohjima, Y., Kim, S.-Y., Lee, H., Nisbet, E. G., Fisher, R. E., Lowry, D., Weiss, R. F., Prinn, R. G., O'Doherty, S., Young, D., and White, J. W. C.: Methane emissions in East Asia for 2000–2011 estimated using an atmospheric Bayesian inversion, J. Geophys. Res.-Atmos., 120, 4352–4369, https://doi.org/10.1002/2014JD022394, 2015. a, b"> <meta name="citation_reference" content="Thompson, R. L., Nisbet, E. G., Pisso, I., Stohl, A., Blake, D., Dlugokencky, E. J., Helmig, D., and White, J. W. C.: Variability in Atmospheric Methane From Fossil Fuel and Microbial Sources Over the Last Three Decades, Geophys. Res. Lett., 45, 11499–11508, https://doi.org/10.1029/2018GL078127, 2018. a"> <meta name="citation_reference" content="Turner, A. J. and Jacob, D. J.: Balancing aggregation and smoothing errors in inverse models, Atmos. Chem. Phys., 15, 7039–7048, https://doi.org/10.5194/acp-15-7039-2015, 2015. a"> <meta name="citation_reference" content="Turner, A. J., Jacob, D. J., Wecht, K. J., Maasakkers, J. D., Lundgren, E., Andrews, A. E., Biraud, S. C., Boesch, H., Bowman, K. W., Deutscher, N. M., Dubey, M. K., Griffith, D. W. T., Hase, F., Kuze, A., Notholt, J., Ohyama, H., Parker, R., Payne, V. H., Sussmann, R., Sweeney, C., Velazco, V. A., Warneke, T., Wennberg, P. O., and Wunch, D.: Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data, Atmos. Chem. Phys., 15, 7049–7069, https://doi.org/10.5194/acp-15-7049-2015, 2015. a, b, c, d, e, f, g, h, i, j, k, l"> <meta name="citation_reference" content="Turner, A. J., Jacob, D. J., Benmergui, J., Wofsy, S. C., Maasakkers, J. D., Butz, A., Hasekamp, O., and Biraud, S. C.: A large increase in U.S. methane emissions over the past decade inferred from satellite data and surface observations, Geophys. Res. Lett., 43, 2218–2224, https://doi.org/10.1002/2016GL067987, 2016. a"> <meta name="citation_reference" content="Turner, A. J., Frankenberg, C., Wennberg, P. O., and Jacob, D. J.: Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl, P. Natl. Acad. Sci. USA, 114, 5367–5372, 2017. a, b, c"> <meta name="citation_reference" content="UNFCCC: United Nations Framework Convention on Climate Change: Greenhouse Gas Inventory Data, available at: https://unfccc.int/process/transparency-and-reporting/greenhouse-gas-data/ghg-data-unfccc (last access: 27 April 2019), 2017. a"> <meta name="citation_reference" content="Wang, X., Jacob, D. J., Eastham, S. D., Sulprizio, M. P., Zhu, L., Chen, Q., Alexander, B., Sherwen, T., Evans, M. J., Lee, B. H., Haskins, J. D., Lopez-Hilfiker, F. D., Thornton, J. A., Huey, G. L., and Liao, H.: The role of chlorine in global tropospheric chemistry, Atmos. Chem. Phys., 19, 3981–4003, https://doi.org/10.5194/acp-19-3981-2019, 2019. a"> <meta name="citation_reference" content="Warneke, T., Messerschmidt, J., Notholt, J., Weinzierl, C., Deutscher, N. M., Petri, C., Grupe, P., Vuillemin, C., Truong, F., Schmidt, M., Ramonet, M., and Parmentier, E.: TCCON data from Orléans (FR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.orleans01.R0/1149276, 2014. a"> <meta name="citation_reference" content="Wecht, K. J., Jacob, D. J., Frankenberg, C., Jiang, Z., and Blake, D. R.: Mapping of North American methane emissions with high spatial resolution by inversion of SCIAMACHY satellite data, J. Geophys. Res.-Atmos., 119, 7741–7756, 2014. a, b, c, d"> <meta name="citation_reference" content="Wennberg, P. O., Peacock, S., Randerson, J. T., and Bleck, R.: Recent changes in the air-sea gas exchange of methyl chloroform, Geophys. Res. Lett., 31, L16112, https://doi.org/10.1029/2004GL020476, 2004. a"> <meta name="citation_reference" content="Wennberg, P. O., Roehl, C., Wunch, D., Toon, G. C., Blavier, J.-F., Washenfelder, R. a., Keppel-Aleks, G., Allen, N., and Ayers, J.: TCCON data from Park Falls (US), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.parkfalls01.R0/1149161, 2014a. a"> <meta name="citation_reference" content="Wennberg, P. O., Wunch, D., Roehl, C., Blavier, J.-F., Toon, G. C., and Allen, N.: TCCON data from Caltech (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.pasadena01.R1/1182415, 2014b. a"> <meta name="citation_reference" content="Wennberg, P. O., Roehl, C., Blavier, J.-F., Wunch, D., Landeros, J., and Allen, N.: TCCON data from Jet Propulsion Laboratory (US), 2011, Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.jpl02.R1/1330096, 2016a. a"> <meta name="citation_reference" content="Wennberg, P. O., Wunch, D., Roehl, C., Blavier, J.-F., Toon, G. C., Allen, N., Dowell, P., Teske, K., Martin, C., and Martin, J.: TCCON data from Lamont (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, https://doi.org/10.14291/tccon.ggg2014.lamont01.R1/1255070, 2016b. a"> <meta name="citation_reference" content="Wofsy, S. C.: HIAPER Pole-to-Pole Observations (HIPPO): fine-grained, global-scale measurements of climatically important atmospheric gases and aerosols, Philos. T. R. Soc. S.-A, 369, 2073–2086, 2011. a"> <meta name="citation_reference" content="Worden, J. R., Bloom, A. A., Pandey, S., Jiang, Z., Worden, H. M., Walker, T. W., Houweling, S., and Röckmann, T.: Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget, Nat. Commun., 8, 2227, https://doi.org/10.1038/s41467-017-02246-0, 2017. a, b"> <meta name="citation_reference" content="Wunch, D., Toon, G. C., Blavier, J.-F. L., Washenfelder, R. A., Notholt, J., Connor, B. J., Griffith, D. W., Sherlock, V., and Wennberg, P. O.: The total carbon column observing network, Philos. T. R. Soc. S.-A, 369, 2087–2112, 2011. a"> <meta name="citation_reference" content="Wunch, D., Toon, G. C., Sherlock, V., Deutscher, N. M., Liu, C., Feist, D. G., and Wennberg, P. O.: The Total Carbon Column Observing Network's GGG2014 Data Version, Tech. rep., California Institute of Technology, Pasadena, CA, https://doi.org/10.14291/tccon.ggg2014.documentation.R0/1221662, 2015. a"> <meta name="citation_reference" content="Zavala-Araiza, D., Lyon, D. R., Alvarez, R. A., Davis, K. J., Harriss, R., Herndon, S. C., Karion, A., Kort, E. A., Lamb, B. K., Lan, X., Marchese, A. J., Pacala, S. W., Robinson, A. L., Shepson, P. B., Sweeney, C., Talbot, R., Townsend-Small, A., Yacovitch, T. I., Zimmerle, D. J., and Hamburg, S. P.: Reconciling divergent estimates of oil and gas methane emissions, P. Natl. Acad. Sci. USA, 112, 15597–15602, https://doi.org/10.1073/pnas.1522126112, 2015. a, b"> <meta name="citation_reference" content="Zhang, B., Tian, H., Ren, W., Tao, B., Lu, C., Yang, J., Banger, K., and Pan, S.: Methane emissions from global rice fields: Magnitude, spatiotemporal patterns, and environmental controls, Global Biogeochem. Cy., 30, 1246–1263, 2016. a"> <meta name="citation_reference" content="Zhang, Y., Jacob, D. J., Maasakkers, J. D., Sulprizio, M. P., Sheng, J.-X., Gautam, R., and Worden, J.: Monitoring global tropospheric OH concentrations using satellite observations of atmospheric methane, Atmos. Chem. Phys., 18, 15959–15973, https://doi.org/10.5194/acp-18-15959-2018, 2018. a, b, c, d, e, f, g"> <meta name="citation_pdf_url" content="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.pdf"/> <meta name="citation_xml_url" content="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.xml"/> <meta name="fulltext_pdf" content="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.pdf"/> <meta name="citation_language" content="English"/> <meta name="libraryUrl" content="https://acp.copernicus.org/articles/"/> <meta property="og:image" content="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-avatar-web.png"/> <meta property="og:title" content="Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015"> <meta property="og:description" content="Abstract. We use 2010–2015 observations of atmospheric methane columns from the GOSAT satellite instrument in a global inverse analysis to improve estimates of methane emissions and their trends over the period, as well as the global concentration of tropospheric OH (the hydroxyl radical, methane's main sink) and its trend. Our inversion solves the Bayesian optimization problem analytically including closed-form characterization of errors. This allows us to (1) quantify the information content from the inversion towards optimizing methane emissions and its trends, (2) diagnose error correlations between constraints on emissions and OH concentrations, and (3) generate a large ensemble of solutions testing different assumptions in the inversion. We show how the analytical approach can be used, even when prior error standard deviation distributions are lognormal. Inversion results show large overestimates of Chinese coal emissions and Middle East oil and gas emissions in the EDGAR v4.3.2 inventory but little error in the United States where we use a new gridded version of the EPA national greenhouse gas inventory as prior estimate. Oil and gas emissions in the EDGAR v4.3.2 inventory show large differences with national totals reported to the United Nations Framework Convention on Climate Change (UNFCCC), and our inversion is generally more consistent with the UNFCCC data. The observed 2010–2015 growth in atmospheric methane is attributed mostly to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH trends is small in comparison. We find that the inversion provides strong independent constraints on global methane emissions (546 Tg a−1) and global mean OH concentrations (atmospheric methane lifetime against oxidation by tropospheric OH of 10.8±0.4 years), indicating that satellite observations of atmospheric methane could provide a proxy for OH concentrations in the future."> <meta property="og:url" content="https://acp.copernicus.org/articles/19/7859/2019/"> <meta property="twitter:image" content="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-avatar-web.png"/> <meta name="twitter:card" content="summary_large_image"> <meta name="twitter:title" content="Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015"> <meta name="twitter:description" content="Abstract. We use 2010–2015 observations of atmospheric methane columns from the GOSAT satellite instrument in a global inverse analysis to improve estimates of methane emissions and their trends over the period, as well as the global concentration of tropospheric OH (the hydroxyl radical, methane's main sink) and its trend. Our inversion solves the Bayesian optimization problem analytically including closed-form characterization of errors. This allows us to (1) quantify the information content from the inversion towards optimizing methane emissions and its trends, (2) diagnose error correlations between constraints on emissions and OH concentrations, and (3) generate a large ensemble of solutions testing different assumptions in the inversion. We show how the analytical approach can be used, even when prior error standard deviation distributions are lognormal. Inversion results show large overestimates of Chinese coal emissions and Middle East oil and gas emissions in the EDGAR v4.3.2 inventory but little error in the United States where we use a new gridded version of the EPA national greenhouse gas inventory as prior estimate. Oil and gas emissions in the EDGAR v4.3.2 inventory show large differences with national totals reported to the United Nations Framework Convention on Climate Change (UNFCCC), and our inversion is generally more consistent with the UNFCCC data. The observed 2010–2015 growth in atmospheric methane is attributed mostly to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH trends is small in comparison. We find that the inversion provides strong independent constraints on global methane emissions (546 Tg a−1) and global mean OH concentrations (atmospheric methane lifetime against oxidation by tropospheric OH of 10.8±0.4 years), indicating that satellite observations of atmospheric methane could provide a proxy for OH concentrations in the future."> <link rel="icon" href="https://www.atmospheric-chemistry-and-physics.net/favicon.ico" type="image/x-icon"/> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/jquery/1.11.1/ui/jquery-ui.min.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/jquery/1.11.1/ui/jquery-ui-slider-pips.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/jquery/1.11.1/ui/template_jquery-ui-touch.min.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/js/respond.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/highstock/2.0.4/highstock.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/apps/htmlgenerator/js/CoPublisher.js"></script> <script type="text/x-mathjax-config"> MathJax.Hub.Config({ "HTML-CSS": { fonts: ["TeX"] ,linebreaks: { automatic: true, width: "90% container" } } }); </script> <script type="text/javascript" async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js?config=MML_HTMLorMML-full"></script> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe-ui-default.min.js"></script> <script type="text/javascript" src="https://cdn.copernicus.org/libraries/photoswipe/4.1/photoswipe.min.js"></script> <script type="text/javascript"> /* <![CDATA[ */ /* ]]> */ </script> <style type="text/css"> .top_menu { margin-right: 0!important; } </style> </head><body><header id="printheader" class="d-none d-print-block container"> <img src="https://contentmanager.copernicus.org/800952/10/ssl" alt="" style="width: 508px; height: 223px;" /> </header> <header class="d-print-none mb-n3 version-2023"> <div class="container"> <div class="row no-gutters mr-0 ml-0 align-items-center header-wrapper mb-lg-3"> <div class="col-auto pr-3"> <div class="layout__moodboard-logo-year-container"> <a class="layout__moodboard-logo-link" target="_blank" href="http://www.egu.eu"> <div class="layout__moodboard-logo"> <img src="https://contentmanager.copernicus.org/800952/10/ssl" alt="" style="width: 508px; height: 223px;" /> </div> </a> </div> </div> <div class="d-none d-lg-block col text-md-right layout__title-desktop"> <div class="layout__m-location-and-time"> <a class="moodboard-title-link" href="https://www.atmospheric-chemistry-and-physics.net/"> Atmospheric Chemistry and Physics </a> </div> </div> <div class="d-none d-md-block d-lg-none col text-md-right layout__title-tablet"> <div class="layout__m-location-and-time"> <a class="moodboard-title-link" href="https://www.atmospheric-chemistry-and-physics.net/"> Atmospheric Chemistry and Physics </a> </div> </div> <div class="col layout__m-location-and-time-mobile d-md-none text-center layout__title-mobile"> <a class="moodboard-title-link" href="https://www.atmospheric-chemistry-and-physics.net/"> ACP </a> </div>  <div class="col-auto text-right"> <button class="navbar-toggler light mx-auto mr-sm-0" type="button" data-toggle="collapse" data-target="#navbar_menu" aria-controls="navbar_menu" aria-expanded="false" aria-label="Toggle navigation"> <span class="navbar-toggler-icon light"></span> </button> </div>  <div class="topbar d-print-none">  </div>  </div> </div> <div class="banner-navigation-breadcrumbs-wrapper"> <div id="navigation"> <nav class="container navbar navbar-expand-lg navbar-light"> <div class="collapse navbar-collapse CMSCONTAINER" id="navbar_menu"> <div id="cmsbox_126167" class="cmsbox navbar-collapse"><button style="display: none;" class="navbar-toggler navigation-extended-toggle-button" type="button" data-toggle="collapse" data-target="#navbar_menu" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"> <span class="navbar-toggler-icon"></span> </button> <div class="navbar-collapse CMSCONTAINER collapse show" id="navbarSupportedContent"> <ul class="navbar-nav mr-auto no-styling"> <li class="nav-item "> <a target="_parent" class="nav-link active " href="https://www.atmospheric-chemistry-and-physics.net/home.html"><i class='fal fa-home fa-lg' title='Home'></i></a> </li> <li class="nav-item megamenu "> <a target="_self" class="nav-link dropdown-toggle " href="#" id="navbarDropdown10845" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Articles & preprints <span class="caret"></span></a> <div class="dropdown-menu level-1 " aria-labelledby="navbarDropdown10845"> <div class="container"> <div class="row"> <div class="col-md-12 col-lg-4 col-sm-12"> <div class="dropdown-header">Recent</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/">Recent papers</a> </div> <div class="dropdown-header">Highlights</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/acp_letters.html">ACP Letters</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/editors_choice.html">Editor's choice</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/opinion.html">Opinions</a> </div> <div class="dropdown-header">Regular articles</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/research_article.html">Research articles</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/review_article.html">Review articles</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/measurement_report.html">Measurement reports</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/technical_note.html">Technical notes</a> </div> </div> <div class="col-md-12 col-lg-4 col-sm-12"> <div class="dropdown-header">Special issues</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/special_issue_overview.html">SI overview articles</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://acp.copernicus.org/special_issues.html">Published SIs</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/articles_and_preprints/scheduled_sis.html">Scheduled SIs</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/articles_and_preprints/how_to_apply_for_an_si.html">How to apply for an SI</a> </div> <div class="dropdown-header">EGU Compilations</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_blank" class="" href="https://egu-letters.net/">EGU Letters</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_blank" class="" href="https://encyclopedia-of-geosciences.net/">Encyclopedia of Geosciences</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_blank" class="" href="https://egusphere.net/">EGUsphere</a> </div> </div> <div class="col-md-12 col-lg-4 col-sm-12"> <div class="dropdown-header">Alerts</div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/articles_and_preprints/subscribe_to_alerts.html">Subscribe to alerts</a> </div> </div> </div> </div> </div> </li> <li class="nav-item "> <a target="_parent" class="nav-link " href="https://www.atmospheric-chemistry-and-physics.net/submission.html">Submission</a> </li> <li class="nav-item dropdown "> <a target="_self" class="nav-link dropdown-toggle " href="#" id="navbarDropdown10849" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Policies <span class="caret"></span></a> <div class="dropdown-menu level-1 " aria-labelledby="navbarDropdown10849"> <div > <div > <div class="col-md-12 col-lg-12 col-sm-12"> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/licence_and_copyright.html">Licence & copyright</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/general_terms.html">General terms</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/guidelines_for_authors.html">Guidelines for authors</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/guidelines_for_editors.html">Guidelines for editors</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/publication_policy.html">Publication policy</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/data_policy.html">Data policy</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/publication_ethics.html">Publication ethics</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/inclusivity_in_global_research.html">Inclusivity in global research</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/competing_interests_policy.html">Competing interests policy</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/appeals_and_complaints.html">Appeals & complaints</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/proofreading_guidelines.html">Proofreading guidelines</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/obligations_for_authors.html">Obligations for authors</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/obligations_for_editors.html">Obligations for editors</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/obligations_for_referees.html">Obligations for referees</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/policies/author_name_change.html">Inclusive author name-change policy</a> </div> </div> </div> </div> </div> </li> <li class="nav-item dropdown "> <a target="_self" class="nav-link dropdown-toggle " href="#" id="navbarDropdown300" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Peer review <span class="caret"></span></a> <div class="dropdown-menu level-1 " aria-labelledby="navbarDropdown300"> <div > <div > <div class="col-md-12 col-lg-12 col-sm-12"> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/peer_review/interactive_review_process.html">Interactive review process</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/peer_review/finding_an_editor.html">Finding an editor</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/peer_review/review_criteria.html">Review criteria</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://webforms.copernicus.org/ACP/referee-application">Become a referee</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a data-non-mobile-optimized="1" target="_parent" class="" href="https://editor.copernicus.org/ACP/my_manuscript_overview">Manuscript tracking</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/peer_review/reviewer_recognition.html">Reviewer recognition</a> </div> </div> </div> </div> </div> </li> <li class="nav-item "> <a target="_parent" class="nav-link " href="https://www.atmospheric-chemistry-and-physics.net/editorial_board.html">Editorial board</a> </li> <li class="nav-item dropdown "> <a target="_self" class="nav-link dropdown-toggle " href="#" id="navbarDropdown29677" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Awards <span class="caret"></span></a> <div class="dropdown-menu level-1 " aria-labelledby="navbarDropdown29677"> <div > <div > <div class="col-md-12 col-lg-12 col-sm-12"> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/awards/outstanding-referee-awards.html">Outstanding referee awards</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/awards/outstanding-editor-award.html">Outstanding editor award</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/awards/paul-crutzen-publication-award.html">Paul Crutzen Publication award</a> </div> </div> </div> </div> </div> </li> <li class="nav-item dropdown "> <a target="_self" class="nav-link dropdown-toggle " href="#" id="navbarDropdown6086" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">About <span class="caret"></span></a> <div class="dropdown-menu level-1 " aria-labelledby="navbarDropdown6086"> <div > <div > <div class="col-md-12 col-lg-12 col-sm-12"> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/aims_and_scope.html">Aims & scope</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/subject_areas.html">Subject areas</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/manuscript_types.html">Manuscript types</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/article_processing_charges.html">Article processing charges</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/financial_support.html">Financial support</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/promote_your_work.html">Promote your work</a> </div> <div class="dropdown dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="dropdown-toggle dropdown-item " href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press.html" > News & press<span class="caret"></span> </a> <div class="dropdown-menu level-2 " aria-labelledby="navbarDropdown316"> <div > <div > <div class="col-md-12 col-lg-12 col-sm-12"> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2019-11-27_thanks-to-cristina-facchini-and-rolf-sander-and-welcome-to-barbara-ervens.html">Many thanks to Cristina Facchini and Rolf Sander and welcome to Barbara Ervens as executive editor of ACP</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2020-08-28_first-acp-letter-published.html">First ACP Letter: The value of remote marine aerosol measurements for constraining radiative forcing uncertainty</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2021-01-14_atmospheric-evolution-of-emissions-from-a-boreal-forest-fire-the-formation-of-highly-functionalized-oxygen-nitrogen-and-sulfur-containing-organic-compounds.html">Atmospheric evolution of emissions from a boreal forest fire: the formation of highly functionalized oxygen-, nitrogen-, and sulfur-containing organic compounds</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2021-04-25_observing-the-timescales-of-aerosol-cloud-interactions-in-snapshot-satellite-images.html">Observing the timescales of aerosol–cloud interactions in snapshot satellite images</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2021-10-15_new-acp-letter-how-alkaline-compounds-control-atmospheric-aerosol-particle-acidity.html">New ACP Letter: How alkaline compounds control atmospheric aerosol particle acidity</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2021-11-16_changes-in-biomass-burning-wetland-extent-or-agriculture-drive-atmospheric-nh3-trends-in-select-african-regions.html">Changes in biomass burning, wetland extent, or agriculture drive atmospheric NH3 trends in select African regions</a> </div> <div class="dropdown-item level-3 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/news_and_press/2022-07-18_two-of-acps-founding-executive-editors-step-down.html">Two of ACP's founding executive editors step down</a> </div> </div> </div> </div> </div> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/egu_resources.html">EGU resources</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/journal_statistics.html">Journal statistics</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/journal_metrics.html">Journal metrics</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/abstracted_and_indexed.html">Abstracted & indexed</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/article_level_metrics.html">Article level metrics</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/faqs.html">FAQs</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/contact.html">Contact</a> </div> <div class="dropdown-item level-2 " style="list-style: none"> <a target="_parent" class="" href="https://www.atmospheric-chemistry-and-physics.net/about/xml_harvesting_and_oai-pmh.html">XML harvesting & OAI-PMH</a> </div> </div> </div> </div> </div> </li> <li class="nav-item "> <a target="_parent" class="nav-link " href="https://www.atmospheric-chemistry-and-physics.net/egu_publications.html">EGU publications</a> </li> <li class="nav-item "> <a target="_blank" class="nav-link " data-non-mobile-optimized="1" href="https://editor.copernicus.org/ACP/"><i class='fal fa-sign-in-alt fa-lg' title='Login'></i></a> </li>  <li class="d-print-none d-lg-none pt-2 topbar-mobile">  </li>  </ul> </div> </div></div> </nav> </div> <section id="banner" class="banner dzsparallaxer use-loading auto-init height-is-based-on-content mode-scroll loaded dzsprx-readyall"> <div class="divimage dzsparallaxer--target layout__moodboard-banner" data-src="" style=""></div> <div id="headers-content-container" class="container CMSCONTAINER"> <div id="cmsbox_126230" class="cmsbox "> <span class="header-small text-uppercase"> </span> <h1 class="display-4 header-get-function home-header hide-md-on-version2023"> Article   </h1> </div></div> </section> <div id="breadcrumbs" class="breadcrumbs"> <div class="container"> <div class="row align-items-center"> <div class="d-none d-sm-block text-nowrap pageactions"></div>    <div class="justify-content-between col-auto col-md CMSCONTAINER" id="breadcrumbs_content_container"><div id="cmsbox_1088152" class="cmsbox ">  <ol class="breadcrumb"> <li class="breadcrumb-item"><a href="https://acp.copernicus.org/">Articles</a></li><li class="breadcrumb-item"><a href="https://acp.copernicus.org/articles/19/issue11.html">Volume 19, issue 11</a></li><li class="breadcrumb-item active">ACP, 19, 7859–7881, 2019</li> </ol>  </div></div> <div class="col col-md-4 text-right page-search CMSCONTAINER" id="search_content_container"><div id="cmsbox_1088035" class="cmsbox ">       <div class="pswp" tabindex="-1" role="dialog" aria-hidden="true" >  <div class="pswp__bg"></div>  <div class="pswp__scroll-wrap">  <div class="pswp__container"> <div class="pswp__item"></div> <div class="pswp__item"></div> <div class="pswp__item"></div> </div>  <div class="pswp__ui pswp__ui--hidden"> <div class="pswp__top-bar">  <div class="pswp__counter"></div> <button class="pswp__button pswp__button--close" title="Close (Esc)"></button> <button class="pswp__button pswp__button--fs" title="Toggle fullscreen"></button>   <div class="pswp__preloader"> <div class="pswp__preloader__icn"> <div class="pswp__preloader__cut"> <div class="pswp__preloader__donut"></div> </div> </div> </div> </div> <div class="pswp__share-modal pswp__share-modal--hidden pswp__single-tap"> <div class="pswp__share-tooltip"></div> </div> <button class="pswp__button pswp__button--arrow--left" title="Previous (arrow left)"> </button> <button class="pswp__button pswp__button--arrow--right" title="Next (arrow right)"> </button> <div class="pswp__caption "> <div class="pswp__caption__center"></div> </div> </div> </div> </div> <div class="row align-items-center no-gutters py-1" id="search-wrapper"> <div class="col-auto pl-0 pr-1"> <a id="templateSearchInfoBtn" role="button" tabindex="99" data-container="body" data-toggle="popover" data-placement="bottom" data-trigger="click"><span class="fal fa-info-circle"></span></a> </div> <div class="col pl-0 pr-1"> <input type="search" placeholder="Search" name="q" class="form-control form-control-sm" id="search_query_solr"/> </div> <div class="col-auto pl-0"> <button title="Start site search" id="start_site_search_solr" class="btn btn-sm btn-success"><span class="co-search"></span></button> </div> </div> <div class="text-left"> <div id="templateSearchInfo" class="d-none"> <div> <p> Multiple terms: term1 term2<br /> <i>red apples</i><br /> returns results with all terms like:<br /> <i>Fructose levels in <strong>red</strong> and <strong>green</strong> apples</i><br /> </p> <p> Precise match in quotes: "term1 term2"<br /> <i>"red apples"</i><br /> returns results matching exactly like:<br /> <i>Anthocyanin biosynthesis in <strong>red apples</strong></i><br /> </p> <p> Exclude a term with -: term1 -term2<br /> <i>apples -red</i><br /> returns results containing <i><strong>apples</strong></i> but not <i><strong>red</strong></i>:<br /> <i>Malic acid in green <strong>apples</strong></i><br /> </p> </div> </div> <div class="modal " id="templateSearchResultModal" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-lg modal-dialog-centered"> <div class="modal-content"> <div class="modal-header modal-header--sticky shadow one-column d-block"> <div class="row no-gutters mx-1"> <div class="col mr-3"> <h1 class="" id="resultsSearchHeader"><span id="templateSearchResultNr"></span> hit<span id="templateSearchResultNrPlural">s</span> for <span id="templateSearchResultTerm"></span></h1> </div> <div class="col-auto"> <a id="scrolltopmodal" href="javascript:void(0)" onclick="scrollModalTop();" style="display: none;"><i class="co-home"></i></a> </div> <div class="col-auto"> <button data-dismiss="modal" aria-label="Close" class="btn btn-danger mt-1">Close</button> </div> </div> </div> <div class="modal-body one-column">  <div class="grid-container mx-n3"><div class="grid-85 tablet-grid-85"> <button aria-label="Refine" id="refineSearchModal" class="btn btn-primary float-left mt-4">Refine your search</button> <button aria-label="Refine" id="refineSearchModalHide" class="btn btn-danger float-left d-none mt-4">Hide refinement</button> </div></div> <div class="grid-container mx-n3"><div class="grid-100 tablet-grid-100"><div id="templateRefineSearch" class="d-none"></div></div></div> <div id="templateSearchResultContainer" class="searchResultsModal mx-n3"></div> <div class="grid-container mb-0"><div class="grid-100 tablet-grid-100"><div id="templateSearchResultContainerEmpty" class="co-notification d-none">There are no results for your search term.</div></div></div> </div> </div> </div> </div> </div>  <div class="modal " id="templateSearchErrorModal1" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-lg modal-dialog-centered"> <div class="modal-content p-3"> <div class="modal-body text-left"> <h1 class="mt-0 pt-0">Network problems</h1> <div class="co-error">We are sorry, but your search could not be completed due to network problems. Please try again later.</div> </div> </div> </div> </div>  <div class="modal " id="templateSearchErrorModal2" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-lg modal-dialog-centered"> <div class="modal-content p-3"> <div class="modal-body text-left"> <h1 class="mt-0 pt-0">Server timeout</h1> <div class="co-error">We are sorry, but your search could not be completed due to server timeouts. Please try again later.</div> </div> </div> </div> </div>  <div class="modal " id="templateSearchErrorModal3" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-lg modal-dialog-centered"> <div class="modal-content p-3"> <div class="modal-body text-left"> <h1 class="mt-0 pt-0">Empty search term</h1> <div class="co-error">You have applied the search with an empty search term. Please revisit and try again.</div> </div> </div> </div> </div>  <div class="modal " id="templateSearchErrorModal4" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-lg modal-dialog-centered"> <div class="modal-content p-3"> <div class="modal-body text-left"> <h1 class="mt-0 pt-0">Too many requests</h1> <div class="co-error">We are sorry, but we have received too many parallel search requests. Please try again later.</div> </div> </div> </div> </div>  <div class="modal " id="templateSearchLoadingModal" role="dialog" aria-labelledby="Search results" aria-hidden="true"> <div class="modal-dialog modal-sm modal-dialog-centered"> <div class="modal-content p-3 co_LoadingDotsContainer"> <div class="modal-body"> <div class="text">Searching</div> <div class="dots d-flex justify-content-center"><div class="dot"></div><div class="dot"></div><div class="dot"></div></div></div> </div> </div> </div> </div> <style> /*.modal {*/ /* background: rgba(255, 255, 255, 0.8);*/ /*}*/ .modal-header--sticky { position: sticky; top: 0; background-color: inherit; z-index: 1055; } .grid-container { margin-bottom: 1em; /*padding-left: 0;*/ /*padding-right: 0;*/ } #templateSearchInfo{ display: none; background-color: var(--background-color-primary); margin-top: 1px; z-index: 5; border: 1px solid var(--color-primary); opacity: .8; font-size: .7rem; border-radius: .25rem; } #templateSearchLoadingModal .co_LoadingDotsContainer { z-index: 1000; } #templateSearchLoadingModal .co_LoadingDotsContainer .text { text-align: center; font-weight: bold; padding-bottom: 1rem; } #templateSearchLoadingModal .co_LoadingDotsContainer .dot { background-color: #0072BC; border: 2px solid white; border-radius: 50%; float: left; height: 2rem; width: 2rem; margin: 0 5px; -webkit-transform: scale(0); transform: scale(0); -webkit-animation: animation_dots_breath 1000ms ease infinite 0ms; animation: animation_dots_breath 1000ms ease infinite 0ms; } #templateSearchLoadingModal .co_LoadingDotsContainer .dot:nth-child(2) { -webkit-animation: animation_dots_breath 1000ms ease infinite 300ms; animation: animation_dots_breath 1000ms ease infinite 300ms; } #templateSearchLoadingModal .co_LoadingDotsContainer .dot:nth-child(3) { -webkit-animation: animation_dots_breath 1000ms ease infinite 600ms; animation: animation_dots_breath 1000ms ease infinite 600ms; } #templateSearchResultModal [class*="grid-"] { padding-left: 10px !important; padding-right: 10px !important; } #templateSearchResultTerm { font-weight: bold; } #resultsSearchHeader { display: block !important; } #scrolltopmodal { font-size: 3.0em; margin-top: 0 !important; margin-right: 15px; } @-webkit-keyframes animation_dots_breath { 50% { -webkit-transform: scale(1); transform: scale(1); opacity: 1; } 100% { opacity: 0; } } @keyframes animation_dots_breath { 50% { -webkit-transform: scale(1); transform: scale(1); opacity: 1; } 100% { opacity: 0; } } @media (min-width: 768px) and (max-width: 991px) { #templateSearchResultModal .modal-dialog { max-width: 90%; } } </style> <script> if(document.querySelector('meta[name="global_moBaseURL"]').content == "https://meetingorganizer.copernicus.org/") FINDER_URL = document.querySelector('meta[name="global_moBaseURL"]').content.replace('meetingorganizer', 'finder-app')+"search/library.php"; else FINDER_URL = document.querySelector('meta[name="global_moBaseURL"]').content.replace('meetingorganizer', 'finder')+"search/library.php"; SEARCH_INPUT = document.getElementById('search_query_solr'); SEARCH_INPUT_MODAL = document.getElementById('search_query_modal'); searchRunning = false; offset = 20; INITIAL_OFFSET = 20; var MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver; const targetNodeSearchModal = document.getElementById("templateSearchResultModal"); const configSearchModal = { attributes: true, childList: true, subtree: true }; // Callback function to execute when mutations are observed const callbackSearchModal = (mutationList, observer) => { for (const mutation of mutationList) { if (mutation.type === "childList") { // console.log("A child node has been added or removed."); picturesGallery(); } else if (mutation.type === "attributes") { // console.log(`The ${mutation.attributeName} attribute was modified.`); } } }; // Create an observer instance linked to the callback function const observer = new MutationObserver(callbackSearchModal); // Start observing the target node for configured mutations observer.observe(targetNodeSearchModal, configSearchModal); function _addEventListener() { document.getElementById('search_query_solr').addEventListener('keypress', (e) => { if (e.key === 'Enter') _runSearch(); }); document.getElementById('start_site_search_solr').addEventListener('click', (e) => { _runSearch(); e.stopPropagation(); e.stopImmediatePropagation(); return false; }); $('#templateSearchResultModal').scroll(function() { if ($(this).scrollTop()) { $('#scrolltopmodal:hidden').stop(true, true).fadeIn().css("display","inline-block"); } else { $('#scrolltopmodal').stop(true, true).fadeOut(); } }); } function scrollModalTop() { $('#templateSearchResultModal').animate({ scrollTop: 0 }, 'slow'); // $('#templateSearchResultModal').scrollTop(0); } function picturesGallery() { $('body').off('click', '.paperlist-avatar img'); $('body').off('click', '#templateSearchResultContainer .paperlist-avatar img'); searchPaperListAvatar = []; searchPaperListAvatarThumb = []; search_pswpElement = document.querySelectorAll('.pswp')[0]; if (typeof search_gallery != "undefined") { search_gallery = null; } $('body').on('click', '#templateSearchResultContainer .paperlist-avatar img', function (e) { if(searchPaperListAvatarThumb.length === 0 && searchPaperListAvatar.length === 0) { $('#templateSearchResultContainer .paperlist-avatar img').each(function () { var webversion = $(this).attr('data-web'); var width = $(this).attr('data-width'); var height = $(this).attr('data-height'); var caption = $(this).attr('data-caption'); var figure = { src: webversion, w: width, h: height, title: caption }; searchPaperListAvatarThumb.push($(this)[0]); searchPaperListAvatar.push(figure); }); } var target = $(this); var index = $('#templateSearchResultContainer .paperlist-avatar img').index(target); var options = { showHideOpacity:false, bgOpacity:0.8, index:index, spacing:0.15, history: false, focus:false, getThumbBoundsFn: function(index) { var thumbnail = searchPaperListAvatarThumb[index]; var pageYScroll = window.pageYOffset || document.documentElement.scrollTop; var rect = thumbnail.getBoundingClientRect(); return {x:rect.left, y:rect.top + pageYScroll, w:rect.width}; } }; search_gallery = new PhotoSwipe( search_pswpElement, PhotoSwipeUI_Default,[searchPaperListAvatar[index]],options); search_gallery.init(); }); } function showError(code, msg) { console.error(code, msg); $("#templateSearchLoadingModal").modal("hide"); switch(code) { case -3: // http request fail case -2: // invalid MO response case 4: // CORS case 1: // project $("#templateSearchErrorModal1").modal({}); break; case -1: // timeout $("#templateSearchErrorModal2").modal({}); break; case 2: // empty term $("#templateSearchErrorModal3").modal({}); break; case 3: // DOS $("#templateSearchErrorModal4").modal({}); break; default: $("#templateSearchErrorModal1").modal({}); break; } } function clearForm() { var myFormElement = document.getElementById("library-filters") var elements = myFormElement.elements; $(".form-check-input").prop('checked', false).change().parent().removeClass('active'); for(i=0; i<elements.length; i++) { field_type = elements[i].type.toLowerCase(); switch(field_type) { case "text": case "password": case "textarea": case "hidden": elements[i].value = ""; break; case "radio": case "checkbox": if (elements[i].checked) { elements[i].checked = false; } break; case "select-one": case "select-multi": elements[i].selectedIndex = -1; break; default: break; } } } function generateShowMoreButton(offset, term) { var code = '<button aria-label="ShowMore" id="showMore" class="btn btn-success float-right mr-2" data-offset="' + offset + '">Show more</button>'; return code; } function hideModal(id) { $("#"+id).modal('hide'); } function showModal(id) { $("#"+id).modal({}); } function prepareForPhotoSwipe() { searchPaperListAvatar = []; searchPaperListAvatarThumb = []; search_pswpElement = document.querySelectorAll('.pswp')[0]; } function _sendAjax(projectID, term) { let httpRequest = new XMLHttpRequest(); if(searchRunning) { console.log("Search running"); return; } if (!httpRequest) { console.error("Giving up :( Cannot create an XMLHTTP instance"); showError(-1); return false; } // httpRequest.timeout = 20000; // time in milliseconds httpRequest.withCredentials = false; httpRequest.ontimeout = (e) => { showError(-1, "result timeout"); searchRunning = false; }; httpRequest.onreadystatechange = function() { if (httpRequest.readyState === XMLHttpRequest.DONE) { searchRunning = false; if (httpRequest.status === 200) { let rs = JSON.parse(httpRequest.responseText); if(rs) { if(rs.isError) { showError(rs.errorCode, rs.errorMessage); } else { let html = rs.resultHTMLs; $("#modal_search_query").val(rs.term); $("#templateSearchResultTerm").html(rs.term); $("#templateSearchResultNr").html(rs.resultsNr); $("#templateRefineSearch").html(rs.filter); if(rs.filter == false) { console.log('filter empty'); $("#refineSearchModal").removeClass('d-block').addClass('d-none'); } if(rs.resultsNr==1) $("#templateSearchResultNrPlural").hide(); else $("#templateSearchResultNrPlural").show(); if(rs.resultsNr==0) { hideModal('templateSearchLoadingModal'); $("#templateSearchResultContainer").html(""); $("#templateSearchResultContainerEmpty").removeClass("d-none"); showModal('templateSearchResultModal'); } else { if((rs.resultsNr - offset)>0) { html = html + generateShowMoreButton(offset, term); } $("#templateSearchResultContainerEmpty").addClass("d-none"); if( offset == INITIAL_OFFSET) { hideModal('templateSearchLoadingModal'); $("#templateSearchResultContainer").html(html); showModal('templateSearchResultModal'); } else { $('#showMore').remove(); startHtml = $("#templateSearchResultContainer").html(); $("#templateSearchResultContainer").html(startHtml + html); } // prepareForPhotoSwipe(); } } } else { showError(-2, "invalid result"); } } else { showError(-3, "There was a problem with the request."); } } }; if(offset == INITIAL_OFFSET) { hideModal('templateSearchResultModal'); showModal('templateSearchLoadingModal'); } httpRequest.open("GET", FINDER_URL+"?project="+projectID+"&term="+encodeURI(term)+((offset>INITIAL_OFFSET)?("&offset="+(offset-INITIAL_OFFSET)) : "")); httpRequest.send(); searchRunning = true; } function _runSearch() { var projectID = document.querySelector('meta[name="global_projectID"]').content; var term = _searchTrimInput(SEARCH_INPUT.value); if(term.length > 0) { _sendAjax(projectID, term); } else { showError(2, 'Empty search term') } } function _searchTrimInput(str) { return str.replace(/^\s+|\s+$/gm, ''); } function run() { _addEventListener(); $('#templateSearchInfoBtn, #modalSearchInfoBtn').popover({ sanitize: false, html: true, content: $("#templateSearchInfo").html(), placement: "bottom", template: '<div class="popover" role="tooltip"><div class="arrow"></div><button class="m-1 float-right btn btn-sm btn-danger" id="templateSearchInfoClose"><i class="fas fa-times-circle"></i></button><h3 class="popover-header"></h3><div class="popover-body"></div></div>', title: "Search tips", }); $(document).click(function (e) { let t = $(e.target); let a = t && t.attr("data-toggle")!=="popover" && t.parent().attr("data-toggle")!=="popover"; let b = t && $(".popover").has(t).length===0; if(a && b) { $('#templateSearchInfoBtn').popover('hide'); $('#modalSearchInfoBtn').popover('hide'); } }); $('#templateSearchInfoBtn').on('shown.bs.popover', function () { $("#templateSearchInfoClose").click(function(e){ $('#templateSearchInfoBtn').popover('hide'); e.stopPropagation(); e.stopImmediatePropagation(); return false; }); }) $('#templateSearchResultModal').on('hidden.bs.modal', function(e) { $('body').off('click', '#templateSearchResultContainer .paperlist-avatar img'); var pswpElement = document.querySelectorAll('.pswp')[0]; var gallery = null; var paperListAvatar = []; var paperListAvatarThumb = []; $('.paperlist-avatar img').each(function(){ var webversion = $(this).attr('data-web'); var width = $(this).attr('data-width'); var height = $(this).attr('data-height'); var caption =$(this).attr('data-caption'); var figure = { src:webversion, w:width, h:height, title:caption }; paperListAvatarThumb.push($(this)[0]); paperListAvatar.push(figure); }); $('body').on('click', '.paperlist-avatar img', function (e) { if(paperListAvatarThumb.length === 0 && paperListAvatar.length === 0){ $('.paperlist-avatar img').each(function(){ var webversion = $(this).attr('data-web'); var width = $(this).attr('data-width'); var height = $(this).attr('data-height'); var caption =$(this).attr('data-caption'); var figure = { src:webversion, w:width, h:height, title:caption }; paperListAvatarThumb.push($(this)[0]); paperListAvatar.push(figure); }); } var target = $(this); var index = $('.paperlist-avatar img').index(target); var options = { showHideOpacity:true, bgOpacity:0.8, index:index, spacing:0.15, getThumbBoundsFn: function(index) { var thumbnail = paperListAvatarThumb[index]; var pageYScroll = window.pageYOffset || document.documentElement.scrollTop; var rect = thumbnail.getBoundingClientRect(); return {x:rect.left, y:rect.top + pageYScroll, w:rect.width}; } }; gallery = new PhotoSwipe( pswpElement, PhotoSwipeUI_Default,[paperListAvatar[index]],options); gallery.init(); }); }); $('#templateSearchResultModal').on('hide.bs.modal', function(e) { $("#templateRefineSearch").removeClass('d-block').addClass('d-none'); $("#refineSearchModalHide").removeClass('d-block').addClass('d-none'); $("#refineSearchModal").removeClass('d-none').addClass('d-block'); offset = INITIAL_OFFSET; }) $(document).on("click", "#showMore", function(e){ offset+=INITIAL_OFFSET; runSearchModal() e.stopPropagation(); e.stopImmediatePropagation(); return false; }); $(document).ready(function() { $(document).on("click", "#refineSearchModal", function (e) { $("#templateRefineSearch").removeClass('d-none').addClass('d-block'); $(this).removeClass('d-block').addClass('d-none'); $("#refineSearchModalHide").removeClass('d-none').addClass('d-block'); }); $(document).on("click", "#refineSearchModalHide", function (e) { $("#templateRefineSearch").removeClass('d-block').addClass('d-none'); $(this).removeClass('d-block').addClass('d-none'); $("#refineSearchModal").removeClass('d-none').addClass('d-block'); }); $(document).on("click", "#modal_start_site_search", function (e) { runSearchModal(); e.stopPropagation(); e.stopImmediatePropagation(); return false; }); }); } function runSearchModal() { var projectID = document.querySelector('meta[name="global_projectID"]').content; var queryString = $('#library-filters').serialize(); var term = _searchTrimInput($('#modal_search_query').val()); term+='&'+queryString; if(term.length > 0) { _sendAjax(projectID, term); } else { showError(2, 'Empty search term') } } if(document.getElementById('search_query_solr')) { run(); } </script> </div></div> </div> </div> </div> </div> </header>  <main class="one-column version-2023"> <div id="content" class="container"> <div id="page_content_container" class="CMSCONTAINER row"> <div class="col"> <div class="article"> <div id="top"></div> <div class="row no-gutters header-block mb-1 align-items-end"> <div class="col-12 col-xl-5"> <div class="row d-xl-none mb-3"> <div class="col-12" > <div class="d-none d-lg-block articleBackLink"> <a href="https://acp.copernicus.org/">Articles</a> | <a href="https://acp.copernicus.org/articles/19/issue11.html">Volume 19, issue 11</a> </div> <div class="tab co-angel-left d-md-none"></div> <div class="tab co-angel-right d-md-none"></div> <div class="mobile-citation"> <ul class="tab-navigation no-styling"> <li class="tab1.articlf active"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.html">Article</a></nobr></li><li class="tab2.assett"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-assets.html">Assets</a></nobr></li><li class="tab3.discussioo"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-discussion.html">Peer review</a></nobr></li><li class="tab450.metrict"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-metrics.html">Metrics</a></nobr></li><li class="tab500.relationt"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-relations.html">Related articles</a></nobr></li> </ul> </div> </div> </div> <div class="d-lg-none"> <span class="articleBackLink"><a href="https://acp.copernicus.org/">Articles</a> | <a href="https://acp.copernicus.org/articles/19/issue11.html">Volume 19, issue 11</a> </span> <div class="citation-header" id="citation-content"> <div class="citation-doi">https://doi.org/10.5194/acp-19-7859-2019</div> <div class="citation-copyright">© Author(s) 2019. This work is distributed under <br class="hide-on-mobile hide-on-tablet" />the Creative Commons Attribution 4.0 License.</div> </div> </div> <div class="hide-on-mobile hide-on-tablet"> <div class="citation-header"> <div class="citation-doi">https://doi.org/10.5194/acp-19-7859-2019</div> <div class="citation-copyright">© Author(s) 2019. This work is distributed under <br class="hide-on-mobile hide-on-tablet" />the Creative Commons Attribution 4.0 License.</div> </div> </div> </div> <div class="col-7 d-none d-xl-block"> <div class="text-right articleBackLink"> <a href="https://acp.copernicus.org/">Articles</a> | <a href="https://acp.copernicus.org/articles/19/issue11.html">Volume 19, issue 11</a> </div> <div class="tab co-angel-left d-md-none"></div> <div class="tab co-angel-right d-md-none"></div> <div class="mobile-citation"> <ul class="tab-navigation no-styling"> <li class="tab1.articlf active"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.html">Article</a></nobr></li><li class="tab2.assett"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-assets.html">Assets</a></nobr></li><li class="tab3.discussioo"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-discussion.html">Peer review</a></nobr></li><li class="tab450.metrict"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-metrics.html">Metrics</a></nobr></li><li class="tab500.relationt"><nobr><a href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-relations.html">Related articles</a></nobr></li> </ul> </div> </div> </div> <div class="ms-type row no-gutters d-none d-lg-flex mb-1 mt-0 align-items-center"> <div class="col"> <div class="row no-gutters align-items-center"> <div class="col-auto"> Research article </div> <div class="col-auto">  | <strong>Highlight paper</strong> </div> <div class="col">  | <a target="_blank" href="https://creativecommons.org/licenses/by/4.0/" rel="license" class="licence-icon-svg"><img src="https://www.atmospheric-chemistry-and-physics.net/licenceSVG_16.svg"></a> </div> </div> </div> <div class="col-auto text-right">12 Jun 2019</div> </div> <div class="ms-type row no-gutters d-lg-none mb-1 align-items-center"> <div class="col-12"> Research article | <strong>Highlight paper</strong> | <a target="_blank" href="https://creativecommons.org/licenses/by/4.0/" rel="license" class="licence-icon-svg "><img src="https://www.atmospheric-chemistry-and-physics.net/licenceSVG_16.svg"></a> | <span>12 Jun 2019</span> </div> </div> <a class="article-avatar hide-on-mobile hide-on-tablet" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-avatar-web.png" target="_blank"> <img border="0" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-avatar-thumb150.png" data-caption="© Authors. Distributed under the Creative Commons Attribution 4.0 License." data-web="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-avatar-web.png" data-width="600" data-height="389"> </a> <h1>Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015</h1> <div class="auto-fixed-top-forced article-title"> <div class="grid-container show-on-fixed" style="display: none"> <div class="grid-85 mobile-grid-85 tablet-grid-85 grid-parent"> <span class="d-block hide-on-mobile hide-on-tablet journal-contentHeaderColor">Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015</span> <span class="d-block hide-on-desktop journal-contentHeaderColor">Global distribution of methane emissions, emission trends, and OH concentrations and trends...</span> <span>Joannes D. Maasakkers et al.</span> </div> <div class="grid-1 mobile-grid-15 tablet-grid-15 grid-parent text-right"> <a id="scrolltop" class="scrollto" href="https://acp.copernicus.org/articles/19/7859/2019/#top"><i class="co-home"></i> </a> </div> </div> </div> <div class="mb-3 authors-with-affiliations"> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535107">Joannes D. Maasakkers<a href="mailto:maasakkers@fas.harvard.edu"><i class="fal fa-envelope ml-1"></i></a></span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535108">Daniel J. Jacob</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535109">Melissa P. Sulprizio</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535110">Tia R. Scarpelli</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535111">Hannah Nesser</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535112">Jian-Xiong Sheng</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535113">Yuzhong Zhang</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535114">Monica Hersher</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535115">A. Anthony Bloom</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535116">Kevin W. Bowman</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535117">John R. Worden</span>,</nobr> <nobr><span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535118">Greet Janssens-Maenhout</span>,</nobr> <nobr>and <span class="hover-cursor-pointer journal-contentLinkColor hover-underline" data-toggle="modal" data-target=".author535119">Robert J. Parker</span></nobr> </div> <div class="modal fade author535107" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Joannes D. Maasakkers</h3> <div class="row no-gutters"> <div class="col-12">CORRESPONDING AUTHOR</div> <div class="col-12"><a href="mailto:maasakkers@fas.harvard.edu"><i class="fal fa-envelope mr-2"></i>maasakkers@fas.harvard.edu</a></div> </div> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0001-8118-0311" data-title="https://orcid.org/0000-0001-8118-0311"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0001-8118-0311</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> <div class="row"> <div class="col-12 mb-3"> now at: SRON Netherlands Institute for Space Research, Utrecht, the Netherlands </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535108" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Daniel J. Jacob</h3> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535109" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Melissa P. Sulprizio</h3> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535110" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Tia R. Scarpelli</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0001-5544-8732" data-title="https://orcid.org/0000-0001-5544-8732"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0001-5544-8732</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535111" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Hannah Nesser</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0001-6778-037X" data-title="https://orcid.org/0000-0001-6778-037X"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0001-6778-037X</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535112" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Jian-Xiong Sheng</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0002-8008-3883" data-title="https://orcid.org/0000-0002-8008-3883"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0002-8008-3883</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535113" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Yuzhong Zhang</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0001-5431-5022" data-title="https://orcid.org/0000-0001-5431-5022"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0001-5431-5022</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> <div class="row"> <div class="col-12 mb-3"> Environmental Defense Fund, Washington, DC, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535114" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Monica Hersher</h3> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Harvard University, Cambridge, MA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535115" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">A. Anthony Bloom</h3> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535116" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Kevin W. Bowman</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0002-8659-1117" data-title="https://orcid.org/0000-0002-8659-1117"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0002-8659-1117</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA </div> </div> <div class="row"> <div class="col-12 mb-3"> Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, CA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535117" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">John R. Worden</h3> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535118" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Greet Janssens-Maenhout</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0002-9335-0709" data-title="https://orcid.org/0000-0002-9335-0709"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0002-9335-0709</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> European Commission Joint Research Centre, Ispra (VA), Italy </div> </div> </div> </div> </div> </div> </div> <div class="modal fade author535119" tabindex="-1" aria-hidden="true"> <div class="modal-dialog modal-dialog-centered modal-dialog-scrollable"> <div class="modal-content"> <div class="modal-header"> <div class="container-fluid p-0"> <h3 class="modal-title">Robert J. Parker</h3> <div class="row no-gutters"> <div class="col-12"> <a class="orcid-authors-logo" target="_blank" href="https://orcid.org/0000-0002-0801-0831" data-title="https://orcid.org/0000-0002-0801-0831"><svg class="mr-2" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><image xlink:href="https://www.atmospheric-chemistry-and-physics.net/orcid_icon.svg" src="https://www.atmospheric-chemistry-and-physics.net/orcid_icon_128x128.png" width="100%" height="100%"></image></svg>https://orcid.org/0000-0002-0801-0831</a> </div> </div> </div> <button type="button" class="close" data-dismiss="modal" aria-label="Close"> <span aria-hidden="true">×</span> </button> </div> <div class="modal-body"> <div class="container-fluid p-0"> <div class="row"> <div class="col-12 mb-3"> Earth Observation Science, Department of Physics and Astronomy, University of Leicester, Leicester, UK </div> </div> <div class="row"> <div class="col-12 mb-3"> Leicester Institute for Space and Earth Observation, University of Leicester, Leicester, UK </div> </div> <div class="row"> <div class="col-12 mb-3"> NERC National Centre for Earth Observation, Leicester, UK </div> </div> </div> </div> </div> </div> </div> <div class="abstract sec" id="abstract"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-show="#abstract .co-arrow-open,.abstract-content" data-hide="#abstract .co-arrow-closed,.abstract-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Abstract<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed" style="display:none"></i><i class="co-arrow-open" style="display:inline-block"></i></span></div></span></div> <div class="abstract-content show-no-js"><p id="d1e246">We use 2010–2015 observations of atmospheric methane columns from the GOSAT satellite instrument in a global inverse analysis to improve estimates of methane emissions and their trends over the period, as well as the global concentration of tropospheric OH (the hydroxyl radical, methane's main sink) and its trend. Our inversion solves the Bayesian optimization problem analytically including closed-form characterization of errors. This allows us to (1) quantify the information content from the inversion towards optimizing methane emissions and its trends, (2) diagnose error correlations between constraints on emissions and OH concentrations, and (3) generate a large ensemble of solutions testing different assumptions in the inversion. We show how the analytical approach can be used, even when prior error standard deviation distributions are lognormal. Inversion results show large overestimates of Chinese coal emissions and Middle East oil and gas emissions in the EDGAR v4.3.2 inventory but little error in the United States where we use a new gridded version of the EPA national greenhouse gas inventory as prior estimate. Oil and gas emissions in the EDGAR v4.3.2 inventory show large differences with national totals reported to the United Nations Framework Convention on Climate Change (UNFCCC), and our inversion is generally more consistent with the UNFCCC data. The observed 2010–2015 growth in atmospheric methane is attributed mostly to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH trends is small in comparison. We find that the inversion provides strong independent constraints on global methane emissions (546 Tg a<span class="inline-formula"><sup>−1</sup></span>) and global mean OH concentrations (atmospheric methane lifetime against oxidation by tropospheric OH of <span class="inline-formula">10.8±0.4</span> years), indicating that satellite observations of atmospheric methane could provide a proxy for OH concentrations in the future.</p></div><span class="abstract-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet" style="display:none"></span></div> <div id="oldMobileDownloadBox" class="widget dark-border hide-on-desktop download-and-links"> <div class="legend journal-contentLinkColor">Download & links</div> <div class="content"> <ul class="additional_info no-bullets no-styling"> <li> <a class="triangle" data-toggle=".box-notice" data-duration="300" title="PDF Version (7890 KB)" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.pdf" > Article (PDF, 7890 KB) </a> </li> </ul> </div> </div> <div id="downloadBoxOneColumn" class="widget dark-border hide-on-desktop download-and-links"> <div class="legend journal-contentLinkColor">Download & links</div> <div class="content"> <ul class="additional_info no-bullets no-styling"> <li><a class="triangle" title="PDF Version (7890 KB)" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.pdf">Article</a> <nobr>(7890 KB)</nobr> </li> <li> <a class="triangle" title="XML Version" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.xml">Full-text XML</a> </li> <li><a class="triangle" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.bib">BibTeX</a></li> <li><a class="triangle" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.ris">EndNote</a></li> </ul> </div> </div> <div id="share" class="oneColumnShareMobileBox widget dark-border hide-on-desktop"> <div class="legend journal-contentLinkColor">Share</div> <div class="content row m-0 py-1"> <div class="col-auto pl-0"> <a class="share-one-line" href="https://www.mendeley.com/import/?url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Mendeley" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/mendeley.png" alt="Mendeley"/> </a> </div> <div class="col-auto"> <a class="share-one-line" href="https://www.reddit.com/submit?url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Reddit" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/reddit.png" alt="Reddit"> </a> </div> <div class="col-auto"> <a class="share-one-line last" href="https://twitter.com/intent/tweet?text=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015 https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Twitter" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/twitter.png" alt="Twitter"/> </a> </div> <div class="col-auto"> <a class="share-one-line" href="https://www.facebook.com/share.php?u=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F&t=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015" title="Facebook" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/facebook.png" alt="Facebook"/> </a> </div> <div class="col-auto pr-0"> <a class="share-one-line last" href="https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F&title=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015" title="LinkedIn" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/linkedin.png" alt="LinkedIn"> </a> </div> <div class="col pr-0 mobile-native-share"> <a href="#" data-title="Atmospheric Chemistry and Physics" data-text="*Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015* Joannes D. Maasakkers et al." data-url="https://acp.copernicus.org/articles/19/7859/2019/" class="mobile-native-share share-one-line last"><i class="co-mobile-share display-none"></i></a> </div> </div> </div> <div id="citation-footer" class="sec"> <div class="h1-special journal-contentHeaderColor">How to cite. </div> <div class="citation-footer-content show-no-js"> <p> <div class="citation-footer"> Maasakkers, J. D., Jacob, D. J., Sulprizio, M. P., Scarpelli, T. R., Nesser, H., Sheng, J.-X., Zhang, Y., Hersher, M., Bloom, A. A., Bowman, K. W., Worden, J. R., Janssens-Maenhout, G., and Parker, R. J.: Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015, Atmos. Chem. Phys., 19, 7859–7881, https://doi.org/10.5194/acp-19-7859-2019, 2019. </div> </p> </div> </div> <div id="article-dates" class="sec"> <div class="article-dates dates-content my-3"> <nobr>Received: 31 Dec 2018</nobr> – <nobr>Discussion started: 18 Jan 2019</nobr> – <nobr>Revised: 01 May 2019</nobr> – <nobr>Accepted: 09 May 2019</nobr> – <nobr>Published: 12 Jun 2019</nobr> </div> </div> <div class="sec intro" id="section1"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section1 .co-arrow-open,.section1-content" data-show="#section1 .co-arrow-closed,.section1-mobile-bottom-border"><div id="Ch1.S1" class="h1"><span class="label">1</span> Introduction<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section1-content show-no-js hide-on-mobile-soft"><p id="d1e282">Methane is an important greenhouse gas with a particularly strong decadal climate impact <span class="cit" id="xref_paren.1">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx86" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Stocker et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx86" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. The atmospheric methane concentration has increased by a factor of 2.5 since pre-industrial times <span class="cit" id="xref_paren.2">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx28" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Hartmann et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx28" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. This increase is not well understood but is most<span id="page7860"></span> likely to be mainly driven by anthropogenic activities including the oil and gas industry, coal mining, livestock, landfills, wastewater treatment, biomass burning, and rice cultivation (<span class="cit" id="xref_altparen.3"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx17" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Dlugokencky et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx17" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a></span>; <span class="cit" id="xref_altparen.4"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kirschke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a></span>; <span class="cit" id="xref_altparen.5"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Saunois et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a></span>). Wetlands are the main natural source and could be affected by climate change <span class="cit" id="xref_paren.6">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kirschke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. Atmospheric methane has a lifetime of <span class="inline-formula">9.1±0.9</span> years <span class="cit" id="xref_paren.7">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Prather et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span>, with a dominant sink from oxidation by the hydroxyl radical (OH) that is also subject to interannual variability and trends <span class="cit" id="xref_paren.8">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx32" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Holmes et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx32" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. The methane burden rose by <span class="inline-formula">∼</span> 12 ppb a<span class="inline-formula"><sup>−1</sup></span> in the late 1980s and by <span class="inline-formula">∼</span> 6 ppb a<span class="inline-formula"><sup>−1</sup></span> in the 1990s, plateaued in the early 2000s (<span class="inline-formula">∼</span> 0.5 ppb a<span class="inline-formula"><sup>−1</sup></span>), and has resumed increasing at <span class="inline-formula">∼</span> 7 ppb a<span class="inline-formula"><sup>−1</sup></span> since 2007 (<span class="uri"><a href="https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/" target="_blank">https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/</a></span>, last access: 27 April 2019), for reasons that remain unclear <span class="cit" id="xref_paren.9">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. Inverse analyses can help interpret these trends by combining atmospheric methane observations with a chemical transport model (CTM) to infer the distribution of methane emissions most likely to explain the observations <span class="cit" id="xref_paren.10">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx35" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Houweling et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx35" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Saunois et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx39" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Jacob et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx39" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. Here we use global 2010–2015 methane observations from the GOSAT satellite in an analytical inverse analysis with closed-form error characterization to better quantify methane sources and interpret the recent trend, including changes in both methane emissions and OH concentrations.</p><p id="d1e415">A number of explanations have been proposed for the renewed growth of atmospheric methane concentrations since 2007. A parallel increase in ethane has been proposed as evidence for an increase in oil and gas emissions <span class="cit" id="xref_paren.11">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx30" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Hausmann et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx30" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx23" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Franco et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx23" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. A trend towards isotopically lighter methane has been attributed to an increase in microbial sources such as livestock and wetlands <span class="cit" id="xref_paren.12">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx78" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Schaefer et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx78" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx79" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Schwietzke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx79" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx62" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Nisbet et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx62" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx51" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">McNorton et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx51" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx91" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Thompson et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx91" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. <span class="cit" id="xref_text.13"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx106" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Worden et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx106" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span> suggest that a decrease in open fire emissions may mask the isotopic signature of increasing fossil fuel emissions. Observations of methyl chloroform, a proxy for global OH concentrations, suggest that a decrease in the methane sink may be implicated in the renewed growth <span class="cit" id="xref_paren.14">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx73" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rigby et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx73" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx52" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">McNorton et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx52" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. <span class="cit" id="xref_text.15"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span> find from a global two-box model analysis that the surface record of methane observations is too sparse to arbitrate between methane emissions and OH concentrations as drivers for the methane increase, though <span class="cit" id="xref_text.16"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx61" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Naus et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx61" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span> pointed out that there are inherent biases in the two-box modeling approach.</p><p id="d1e437">GOSAT was launched in 2009 and measures atmospheric methane columns with high precision (0.7 %) by solar backscatter in the shortwave infrared (SWIR) <span class="cit" id="xref_paren.17">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Butz et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Buchwitz et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx44" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kuze et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx44" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. A number of inverse analyses have used the GOSAT data to improve estimates of methane emissions <span class="cit" id="xref_paren.18">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx56" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Monteil et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx56" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx13" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Cressot et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx13" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Alexe et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx64" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Pandey et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx64" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx65" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span>. Here we use the GOSAT data to optimize not only global emissions but also their 2010–2015 trends together with OH concentrations and their trends. The independent optimization of OH and emissions in the inversion is based on the different signatures of those two terms on the methane concentration field <span class="cit" id="xref_paren.19">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. We use an analytical inverse method with closed-form error characterization of the solution, rather than the adjoint approaches used in previous inverse studies that do not provide rigorous characterization of errors. This allows us in particular to diagnose the error correlation between the independent constraints on methane emissions and OH concentrations and their trends. It also allows us to readily conduct inversions for an ensemble of cases once the Jacobian matrix for the problem has been constructed.</p></div><span class="section1-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="sec" id="section2"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section2 .co-arrow-open,.section2-content" data-show="#section2 .co-arrow-closed,.section2-mobile-bottom-border"><div id="Ch1.S2" class="h1"><span class="label">2</span> Data and methods<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section2-content show-no-js hide-on-mobile-soft"><p id="d1e457">We use the GEOS-Chem CTM (<span class="uri"><a href="http://acmg.seas.harvard.edu/geos/" target="_blank">http://acmg.seas.harvard.edu/geos/</a></span>, last access: 27 April 2019) as forward model to simulate the distribution of atmospheric methane and its response to trends. Model results are fit statistically to the GOSAT data by Bayesian optimization, including regularization from prior knowledge of methane emissions and OH concentrations. The January 2010–December 2015 GOSAT methane column data are arranged in an observation vector <span class="inline-formula"><strong><em>y</em></strong></span>, and the inversion optimizes a state vector <span class="inline-formula"><strong><em>x</em></strong></span> including global methane emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="508209b2ece534c1661b4bf4034290cf"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00001.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00001.png"></image></svg></span></span> GEOS-Chem grid, 2010–2015 linear trends of emissions on that same grid, and global mean OH concentrations for individual years (we will also present results from an inversion optimizing a linear OH trend over the 2010–2015 period). The optimal solution <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mi mathvariant="bold-italic">x</mi><mo mathvariant="normal" stretchy="true">^</mo></mover></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="04259ab68e665ad18753bd770998c5c0"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00002.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00002.png"></image></svg></span></span> is obtained by minimizing a Bayesian cost function that balances the information from the observations (weighed by the observational error covariance matrix <span class="inline-formula"><strong>S</strong><sub>O</sub></span>) and the prior knowledge <span class="inline-formula"><strong><em>x</em></strong><sub>a</sub></span> (weighed by the prior error covariance matrix <span class="inline-formula"><strong>S</strong><sub>a</sub></span>) <span class="cit" id="xref_paren.20">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rodgers</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2000</a>)</span>. Below we describe the different elements and steps in the inversion.</p><div class="sec"><h2 id="Ch1.S2.SS1"><span class="label">2.1</span> GOSAT observations</h2> <p id="d1e551">The TANSO-FTS instrument on board the Greenhouse Gases Observing Satellite (GOSAT) observes column-averaged dry-air methane mixing ratios by solar backscatter in the SWIR with near-unit sensitivity down to the surface <span class="cit" id="xref_paren.21">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Butz et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a>)</span>. The satellite is in polar sun-synchronous orbit. Observations are made at around 13:00 local time for circular pixels of 10 km diameter. In the default observation mode, the pixels are separated by <span class="inline-formula">∼</span> 250 km along track and cross track, with repeated observation of the same pixels every 3 days. Denser observations are also made in target mode over features of interest. GOSAT spectra have shown no significant drift or degradation of data quality since the beginning of the record <span class="cit" id="xref_paren.22">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx44" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kuze et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx44" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. We use the University of Leicester version 7 <span class="inline-formula">CO<sub>2</sub></span> proxy retrieval over land <span class="cit" id="xref_paren.23">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx66" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Parker et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx66" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> from January 2010<span id="page7861"></span> to December 2015 in order to have even observations of all seasons. The single-observation precision is 13 ppb, and the relative (regional) bias is 2 ppb compared to ground-based column-averaged dry-air mole factions from the Total Carbon Column Observing Network (TCCON; <span class="cit" id="xref_altparen.24"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Buchwitz et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a></span>). Other retrievals of GOSAT data are consistent with the University of Leicester product <span class="cit" id="xref_paren.25">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Buchwitz et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>. Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">1</a> illustrates the GOSAT data ingested in our inversion, representing a total of 1 211 468 retrievals. Glint data over the oceans and data poleward of 60<span class="inline-formula"><sup>∘</sup></span> are not included because of seasonal sampling biases <span class="cit" id="xref_paren.26">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>.</p> <div class="fig" id="Ch1.F1"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f01-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f01" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f01-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f01-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f01.png" data-width="2067" data-height="1317"></a><div class="caption"><p id="d1e604"><strong class="caption-number">Figure 1</strong>2010–2015 average of the GOSAT methane dry column mixing ratios used in our inversion. Data are from the University of Leicester version 7 <span class="inline-formula">CO<sub>2</sub></span> proxy retrieval <span class="cit" id="xref_paren.27">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Parker et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, excluding glint observations over the oceans and observations poleward of 60<span class="inline-formula"><sup>∘</sup></span>. GOSAT pixels are of 10 km circular diameter and are inflated here to 0.5<span class="inline-formula"><sup>∘</sup></span> for visibility. The red stripes are an averaging artifact as these retrievals are from towards the end of the 2010–2015 time period when methane was higher.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f01.png" target="_blank">Download</a></p></div> </div><div class="sec"><h2 id="Ch1.S2.SS2"><span class="label">2.2</span> Prior estimates</h2> <p id="d1e653">The inversion requires prior estimates and error statistics for all components of the state vector including methane emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="eac76a42c8f102bd2c22a9e14815871a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00003.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00003.png"></image></svg></span></span> GEOS-Chem grid (1009 ice-free land-containing grid cells with prior emissions larger than <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">8</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="42pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1c047fef6dc5dc237a66031409f052b7"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00004.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00004.png"></image></svg></span></span> Mg km<span class="inline-formula"><sup>−2</sup></span> a<span class="inline-formula"><sup>−1</sup></span>, covering 99 % of global emissions), 2010–2015 linear emission trends on the same grid, and global mean OH concentrations for individual years 2009–2015 (2009 is only used for initialization), for a total of 2025 state vector elements.</p> <div class="fig" id="Ch1.F2"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f02-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f02" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f02-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f02-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f02.jpg" data-width="2067" data-height="1531"></a><div class="caption"><p id="d1e720"><strong class="caption-number">Figure 2</strong>Prior estimates of methane emissions from wetlands, livestock, coal mining, oil and gas, wastewater and landfills, and other sources. Values are 2010–2015 averages and are shown on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="202ec83eab1094c9fb6523b0aa8c3996"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00005.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00005.png"></image></svg></span></span> GEOS-Chem grid used for the inversion. Global totals for each source type are given in Table 1.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f02.jpg" target="_blank">Download</a></p></div> <p id="d1e749">Table 1 gives our global prior inventory with the contributions from different source types, and Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2</a> shows the spatial distributions. Monthly wetland emissions for individual years are from the WetCHARTS v1.0 extended ensemble mean <span class="cit" id="xref_paren.28">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bloom et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. For anthropogenic emissions we use the EDGAR v4.3.2 global emission inventory for 2012 (<span class="uri"><a href="https://edgar.jrc.ec.europa.eu/" target="_blank">https://edgar.jrc.ec.europa.eu/</a></span>, last access: 1 December 2017; <span class="cit" id="xref_altparen.29"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx40" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Janssens-Maenhout et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx40" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a></span>) as worldwide default, including additional information from EDGAR to subset the “fuel exploitation” emissions category into oil and gas and coal mining. Over the continental United States, we replace EDGAR v4.3.2 with a gridded version of the US EPA greenhouse gas inventory <span class="cit" id="xref_paren.30">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. In Canada and Mexico, we use the oil and gas emissions from <span class="cit" id="xref_text.31"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx80" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sheng et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx80" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. Anthropogenic emissions are assumed as aseasonal for lack of better prior information except for manure management and rice cultivation. Seasonal scaling of manure management emissions is done using the temperature dependence of <span class="cit" id="xref_text.32"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. Seasonal scaling of rice cultivation emissions is based on <span class="cit" id="xref_text.33"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx110" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx110" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. Daily global open fire emissions are from QFED <span class="cit" id="xref_paren.34">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx14" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Darmenov and da Silva</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx14" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. Termite emissions are from <span class="cit" id="xref_text.35"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx24" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Fung et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx24" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">1991</a>)</span>. Emissions from geological macroseeps (oil and gas seeps and mud volcanoes) are based on <span class="cit" id="xref_text.36"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx21" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Etiope</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx21" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> and <span class="cit" id="xref_text.37"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx45" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kvenvolden and Rogers</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx45" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2005</a>)</span>. For areal seepage, we use the sedimentary basins (microseepage) and potential geothermal seepage maps from <span class="cit" id="xref_text.38"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx45" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kvenvolden and Rogers</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx45" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2005</a>)</span> with the emission factor previously used by <span class="cit" id="xref_text.39"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx49" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Lyon et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx49" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>. Over the United States, we use the sedimentary basin map from the Energy Information Administration <span class="cit" id="xref_paren.40">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx20" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">EIA</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx20" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span> and basin-specific emission factors from <span class="cit" id="xref_text.41"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx22" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Etiope and Klusman</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx22" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2010</a>)</span>. While global geological emissions have previously been estimated to be over 50 Tg a<span class="inline-formula"><sup>−1</sup></span> <span class="cit" id="xref_paren.42">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kirschke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>, <span class="cit" id="xref_text.43"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx70" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Petrenko et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx70" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span> showed that based on ice core measurements they should be no higher than 15 Tg a<span class="inline-formula"><sup>−1</sup></span>.</p> <span class="tableCitations"></span><div class="table-wrap" id="Ch1.T1"><div class="caption"><p id="d1e836"><strong class="caption-number">Table 1</strong>Prior global estimates of methane sources and sinks (mean 2010–2015 values).</p></div><a class="table-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01.png" target="_blank"><img src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01-thumb.png" target="_blank" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01-web.png" data-width="2067" data-height="1929" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01.png" data-csvversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01.xlsx"></a><div class="table-wrap-foot"><p id="d1e839"><span class="inline-formula"><sup>*</sup></span> Including fossil fuel combustion, industrial processes, and agricultural field burning.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor table-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01.png" target="_blank">Download Print Version</a><span class="hide-on-mobile download-separator"> | </span><a class="triangle journal-contentLinkColor table-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t01.xlsx" target="_blank">Download XLSX</a></p></div> <p id="d1e1095"><span id="page7862"></span>Construction of the prior error covariance matrix <span class="inline-formula"><strong>S</strong><sub>a</sub></span> requires estimates of error variances for the prior emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M37" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="a4804cfd8a8b31a48a6c085e0080ca1b"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00006.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00006.png"></image></svg></span></span> grid. For wetland emissions, we use the standard deviation of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M38" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f8685e09b186002a3635e2df6bf411cb"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00007.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00007.png"></image></svg></span></span> annual emissions from the WetCHARTs ensemble members <span class="cit" id="xref_paren.44">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bloom et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. The error variance averages 58 % on the grid level. For US anthropogenic emissions and oil and gas emissions in Canada and Mexico, we use the scale-dependent error variances from <span class="cit" id="xref_text.45"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. For lack of better information, we assume 50 % error standard deviation for EDGAR v4.3.2 emissions <span class="cit" id="xref_paren.46">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> and 100 % for non-wetland natural emissions. The diagonal terms of <span class="inline-formula"><strong>S</strong><sub>a</sub></span> are then constructed by adding the error variances of individual source types for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M40" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="a0b8581b3f777b2db9676ce8b86773ce"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00008.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00008.png"></image></svg></span></span> grid cells in quadrature, capping total errors at 50 %. We assume no error spatial covariance on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M41" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="9c7bfaa27bf38829665099e8e562e250"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00009.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00009.png"></image></svg></span></span> grid so that <span class="inline-formula"><strong>S</strong><sub>a</sub></span> is diagonal. This is a reasonable assumption for anthropogenic emissions <span class="cit" id="xref_paren.47">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>, though errors on wetland emissions may still be correlated on that scale <span class="cit" id="xref_paren.48">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bloom et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>.</p> <p id="d1e1230">Our state vector in the inversion includes linear emission trends for <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M43" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="5657076b80451d6471154ce10d34ae0d"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00010.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00010.png"></image></svg></span></span> grid cells over the 2010–2015 period, superimposed on interannual variability in the case of wetlands and fires. Our global prior estimate of mean methane emissions for the 2010–2015 period exceeds the sinks by 13 Tg a<span class="inline-formula"><sup>−1</sup></span> (Table 1), which drives a 5 ppb a<span class="inline-formula"><sup>−1</sup></span> increase in methane concentrations over that period, even in the absence of an emission trend. Therefore our prior estimate of linear emission trends for individual <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M46" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="4fdd1eb75ce7f9865bafb43a83249af7"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00011.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00011.png"></image></svg></span></span> grid cells is zero, with an absolute error standard deviation of 10 % of the local prior emissions over the 2010–2015 time period (1.7 % a<span class="inline-formula"><sup>−1</sup></span>). This error standard deviation is based on trend estimates for North America inferred from GOSAT data <span class="cit" id="xref_paren.49">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx94" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx94" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sheng et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>)</span>.</p> <p id="d1e1313">The prior estimate of the global tropospheric OH concentration is based on a GEOS-Chem full-chemistry simulation <span class="cit" id="xref_paren.50">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wecht et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span> that yields a methane lifetime <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M48" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="italic">τ</mi><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow><mrow class="chem"><mi mathvariant="normal">OH</mi></mrow></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="22pt" height="19pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="56f6558689d8096a428fb3cb870a2f0b"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00012.svg" width="100%" height="19pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00012.png"></image></svg></span></span> of 10.6 years, consistent with the best estimate inferred from the methyl chloroform proxy <span class="cit" id="xref_paren.51">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Prather et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span> and the <span class="inline-formula">9.7±1.5</span> years estimate from the ACCMIP model ensemble <span class="cit" id="xref_paren.52">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx60" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Naik et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx60" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. Here and elsewhere, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M50" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="italic">τ</mi><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow><mrow class="chem"><mi mathvariant="normal">OH</mi></mrow></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="22pt" height="19pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="ed030846d79ec471bb2c34e3f79f6920"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00013.svg" width="100%" height="19pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00013.png"></image></svg></span></span> is defined as the ratio between the total mass of atmospheric methane (including the stratosphere) and the annual loss rate from oxidation by OH below the tropopause. The uncertainty in the methane lifetime is about 10 % <span class="cit" id="xref_paren.53">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Prather et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span>, but the uncertainty on OH interannual variability is less, about 3 % <span class="cit" id="xref_paren.54">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx32" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Holmes et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx32" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>. We assume a 3 % error standard deviation in the global annual mean OH concentration for our standard inversion but also conduct a sensitivity study with 10 % error standard deviation. We further conduct an inversion taking the OH trend over the 2010–2015 period as linear and assuming in that case error standard deviations of 10 % for the mean global OH concentration and 5 % a<span class="inline-formula"><sup>−1</sup></span> (absolute) for the linear trend. Scaling of global OH concentrations in the inversion is done without modifying the spatial or seasonal OH distribution. <span class="cit" id="xref_text.55"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> found that inversions of atmospheric methane data using the 3-D GEOS-Chem OH fields give consistent results with inversions using other global OH distributions from the ACCMIP model ensemble <span class="cit" id="xref_paren.56">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx60" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Naik et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx60" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>)</span>.</p> </div><div class="sec"><h2 id="Ch1.S2.SS3"><span class="label">2.3</span> Forward model</h2> <p id="d1e1406">We use the GEOS-Chem CTM v11-01 at <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M52" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="5f9fd337361d480152bb438161647908"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00014.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00014.png"></image></svg></span></span> grid resolution <span class="cit" id="xref_paren.57">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wecht et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> as forward<span id="page7863"></span> model for the inversion. The model is driven with 2009–2015 MERRA-2 meteorological fields <span class="cit" id="xref_paren.58">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx8" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bosilovich et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx8" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span> from the NASA Global Modeling and Assimilation Office (GMAO). Atmospheric methane concentrations are initialized on January 2009 using the previous GOSAT inversion results of <span class="cit" id="xref_text.59"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, shown in that work to be unbiased compared to surface and aircraft background data including for the tropospheric meridional gradient.</p> <p id="d1e1438">The loss from oxidation by tropospheric OH is computed with archived 3-D monthly fields of OH concentrations from a GEOS-Chem full-chemistry simulation as described by <span class="cit" id="xref_text.60"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wecht et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span>. Local tropopause information is from the MERRA-2 data. The global loss rate for individual years is optimized in the inversion by uniform scaling of the OH concentrations. Other minor loss terms include stratospheric oxidation computed with archived monthly loss frequencies from the NASA Global Modeling Initiative model <span class="cit" id="xref_paren.61">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx59" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Murray et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx59" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span>, tropospheric oxidation by Cl atoms computed using archived Cl concentration fields from <span class="cit" id="xref_text.62"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx84" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sherwen et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx84" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span> and the reaction rate constant from <span class="cit" id="xref_text.63"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Allan et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2007</a>)</span>, and soil uptake as described by <span class="cit" id="xref_text.64"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx24" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Fung et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx24" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">1991</a>)</span> with temperature-based seasonality based on <span class="cit" id="xref_text.65"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx72" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Ridgwell et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx72" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">1999</a>)</span>. The loss from oxidation by Cl totals 9 Tg a<span class="inline-formula"><sup>−1</sup></span>, intermediate between the 12–13 Tg a<span class="inline-formula"><sup>−1</sup></span> estimated by <span class="cit" id="xref_text.66"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx34" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Hossaini et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx34" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span> using the TOMCAT chemical transport model and 5.3 Tg a<span class="inline-formula"><sup>−1</sup></span> estimated by <span class="cit" id="xref_text.67"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx97" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx97" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span> in a GEOS-Chem simulation with full accounting of tropospheric chlorine. These minor sinks are not optimized in the inversion.</p> <p id="d1e1502">The GEOS-Chem simulation of GOSAT methane columns features a latitude-dependent background bias that needs to be corrected <span class="cit" id="xref_paren.68">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>. This bias likely reflects a model overestimate of methane in the extratropical stratosphere <span class="cit" id="xref_paren.69">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx75" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Saad et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx75" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>, which is common across global models due to excessive meridional transport in the stratosphere <span class="cit" id="xref_paren.70">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx68" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Patra et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx68" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a>)</span> and was first seen in a SCIAMACHY inversion using the TM5 chemical transport model <span class="cit" id="xref_paren.71">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bergamaschi et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2007</a>)</span>. <span class="cit" id="xref_text.72"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Stanevich</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> found a significant difference in methane columns simulated by GEOS-Chem at <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M56" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="5e25150a220ef43a53c2a61ac73f110a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00015.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00015.png"></image></svg></span></span> compared to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M57" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">2</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">2.5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="43pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f9d5bb0802eaf58e1c48d12bc42b8848"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00016.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00016.png"></image></svg></span></span> resolution, but we find that this difference is mainly in the stratosphere (Appendix A). We remove the background bias by applying the latitudinal correction based on background grid cells from <span class="cit" id="xref_text.73"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, recomputed with the University of Leicester v7 GOSAT proxy retrieval <span class="cit" id="xref_paren.74">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Parker et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> and the MERRA-2 meteorological fields. The mean model–GOSAT difference in column mean mixing ratio for background <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M58" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="e935c3638eebf36362a0f32668710770"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00017.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00017.png"></image></svg></span></span> grid cells is fitted to a second-order polynomial of latitude: </p><div class="disp-formula" content-type="numbered" id="Ch1.E1"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M59" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(1)</mtext></mtd><mtd><mrow> <mi mathvariant="italic">ξ</mi> <mo>=</mo> <mfenced open="(" close=")"> <mrow> <mn mathvariant="normal">4.0</mn> <msup> <mi mathvariant="italic">θ</mi> <mn mathvariant="normal">2</mn> </msup> <mo>-</mo> <mn mathvariant="normal">1.3</mn> <mi mathvariant="italic">θ</mi> </mrow> </mfenced> <mo>×</mo> <msup> <mn mathvariant="normal">10</mn> <mrow> <mo>-</mo> <mn mathvariant="normal">3</mn> </mrow> </msup> <mo>-</mo> <mn mathvariant="normal">5</mn> <mo>,</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="186pt" height="22pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="70a67b6d5d757761cf9c0f99a0087261"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_1.svg" width="100%" height="22pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_1.png"></image></svg></div></div><p id="d1e1502-3"> where <span class="inline-formula"><i>θ</i></span> is the latitude in degrees, and <span class="inline-formula"><i>ξ</i></span> is the model correction in ppb. This correction is similar to <span class="cit" id="xref_text.75"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, who used <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M62" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="italic">ξ</mi><mo>=</mo><mfenced close=")" open="("><mrow><mn mathvariant="normal">5</mn><msup><mi mathvariant="italic">θ</mi><mn mathvariant="normal">2</mn></msup><mo>-</mo><mn mathvariant="normal">5</mn><mi mathvariant="italic">θ</mi></mrow></mfenced><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">3</mn></mrow></msup><mo>-</mo><mn mathvariant="normal">0.5</mn></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="136pt" height="22pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="385abef38c8b5619e6d8f3dbbf8dd8cd"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00018.svg" width="100%" height="22pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00018.png"></image></svg></span></span>. A seasonal bias remains after application of this correction, and we fix it by removing the zonal monthly mean concentration differences averaged over rolling 12<span class="inline-formula"><sup>∘</sup></span> latitudinal bands. This seasonal bias may be due to errors in the seasonality of emissions or atmospheric transport <span class="cit" id="xref_paren.76">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx75" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Saad et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx75" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bader et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Stanevich</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. We find that the seasonal correction does not affect the inversion results significantly, as shown in Appendix B, where we optimize emissions for individual seasons separately without applying a seasonal correction.</p> </div><div class="sec"><h2 id="Ch1.S2.SS4"><span class="label">2.4</span> Observational error covariance matrix</h2> <p id="d1e1706">The observational error covariance matrix <span class="inline-formula"><strong>S</strong><sub>O</sub></span> includes contributions from random instrument and forward model errors. We construct it applying the residual error method of <span class="cit" id="xref_text.77"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx31" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Heald et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx31" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2004</a>)</span> using the 2010–2015 time series of local methane column differences <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M65" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><mo>=</mo><msub><mi>y</mi><mtext>GEOS-CHEM, prior</mtext></msub><mo>-</mo><msub><mi>y</mi><mtext>GOSAT</mtext></msub></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="144pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="160040f99b1585ebe1fbea5be511b34c"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00019.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00019.png"></image></svg></span></span> for individual <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M66" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="53d724be981726ba54d6839fb0db17d8"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00020.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00020.png"></image></svg></span></span> grid cells between the GEOS-Chem model with prior estimates (emissions and OH concentrations) and the GOSAT observations after background bias correction. The mean difference <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M67" display="inline" overflow="scroll" dspmath="mathml"><mrow><mover accent="true"><mi mathvariant="normal">Δ</mi><mo mathvariant="normal">‾</mo></mover><mo>=</mo><mover accent="true"><mrow><msub><mi>y</mi><mtext>GEOS-CHEM, prior</mtext></msub><mo>-</mo><msub><mi>y</mi><mtext>GOSAT</mtext></msub></mrow><mo mathvariant="normal">‾</mo></mover></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="146pt" height="17pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="b91e43c96aebfc89680a4fce38ae3e8e"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00021.svg" width="100%" height="17pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00021.png"></image></svg></span></span> is to be corrected in the inversion, while the residual error <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M68" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi mathvariant="normal">Δ</mi><mo>′</mo></msup><mo>=</mo><mi mathvariant="normal">Δ</mi><mo>-</mo><mover accent="true"><mi mathvariant="normal">Δ</mi><mo mathvariant="normal">‾</mo></mover></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="53pt" height="13pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1320ef7dbfcc3e8151c7b345bf2f0195"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00022.svg" width="100%" height="13pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00022.png"></image></svg></span></span> is taken as the observational error. Statistics of <span class="inline-formula">Δ<sup>′</sup></span> define the observational error variance (diagonal of the observational error covariance matrix). The same method was previously used in the satellite-based methane inversions by <span class="cit" id="xref_text.78"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wecht et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span> and <span class="cit" id="xref_text.79"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>. The resulting observational error standard deviation averages 13 ppb. The mean instrument error standard deviation is 11 ppb <span class="cit" id="xref_paren.80">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Parker et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, implying that most of the observational error is generally from the instrument rather than from the forward model. This would indeed be expected for the random error of individual measurements. For a given measurement, if the local error standard deviation computed by the residual error method is smaller than the reported measurement precision, then we use the latter instead; this is the case for 10 % of retrievals. All observational error standard deviations are set to be at least 10 ppb (this threshold affects 8 % of retrievals). <span class="inline-formula"><strong>S</strong><sub>O</sub></span> is taken to be diagonal for lack of better information, but the general effect of error correlation in the observations is accounted for in the inversion by a regularization factor (Sect. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.S2.SS5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2.5</a>).</p> </div><div class="sec"><h2 id="Ch1.S2.SS5"><span class="label">2.5</span> Inversion procedure</h2> <p id="d1e1859"><span id="page7864"></span>We perform inversions with two different specifications of prior error variance statistics: normal and lognormal. Assumption of normally distributed errors enables a linear optimization problem with an analytical solution including closed-form error characterization <span class="cit" id="xref_paren.81">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rodgers</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2000</a>)</span>. Assumption of lognormal errors may be more appropriate for modeling the high tail of the probability density function <span class="cit" id="xref_paren.82">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx109" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zavala-Araiza et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx109" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> and also has the advantage of enforcing positive solutions <span class="cit" id="xref_paren.83">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx54" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx54" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span>, but the optimization problem is then nonlinear. By comparing the two approaches we can evaluate consistency in results.</p> <p id="d1e1872">Both inversions minimize the Bayesian cost function <span class="inline-formula"><i>J</i>(<strong><em>x</em></strong>)</span> <span class="cit" id="xref_paren.84">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rodgers</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2000</a>)</span>: </p><span id="Ch1.E2" class="equationLink"></span><div class="disp-formula" content-type="numbered" specific-use="align"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M72" display="block" overflow="scroll" dspmath="mathml"><mtable columnalign="left" displaystyle="true"><mlabeledtr><mtd><mtext>(2)</mtext></mtd><mtd><mrow><mstyle displaystyle="true" class="stylechange"></mstyle><mi>J</mi><mo>(</mo><mi mathvariant="bold-italic">x</mi><mo>)</mo><mo>=</mo></mrow></mtd><mtd><mrow><mstyle displaystyle="true" class="stylechange"></mstyle><msup><mfenced close=")" open="("><mrow><mi mathvariant="bold-italic">x</mi><mo>-</mo><msub><mi mathvariant="bold-italic">x</mi><mtext>a</mtext></msub></mrow></mfenced><mi>T</mi></msup><msubsup><mi mathvariant="bold">S</mi><mtext>a</mtext><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup><mfenced close=")" open="("><mrow><mi mathvariant="bold-italic">x</mi><mo>-</mo><msub><mi mathvariant="bold-italic">x</mi><mtext>a</mtext></msub></mrow></mfenced><mo>+</mo><mi mathvariant="italic">γ</mi><msup><mfenced close=")" open="("><mrow><mi mathvariant="bold-italic">y</mi><mo>-</mo><mi>F</mi><mo>(</mo><mi mathvariant="bold-italic">x</mi><mo>)</mo></mrow></mfenced><mi>T</mi></msup></mrow></mtd></mlabeledtr><mtr><mtd><mstyle class="stylechange" displaystyle="true"></mstyle></mtd><mtd><mrow><mstyle displaystyle="true" class="stylechange"></mstyle><msubsup><mi mathvariant="bold">S</mi><mtext>O</mtext><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup><mfenced open="(" close=")"><mrow><mi mathvariant="bold-italic">y</mi><mo>-</mo><mi>F</mi><mo>(</mo><mi mathvariant="bold-italic">x</mi><mo>)</mo></mrow></mfenced><mo>,</mo></mrow></mtd></mtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="242pt" height="36pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="3a4ab34d42234cad9487a91eae5b6ae2"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_2.svg" width="100%" height="36pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_2.png"></image></svg></div></div><p id="d1e1872-3"> where <span class="inline-formula"><strong><em>x</em></strong></span> is the state vector, <span class="inline-formula"><strong><em>x</em></strong><sub>a</sub></span> is the prior estimate, <span class="inline-formula"><strong>S</strong><sub>a</sub></span> is the prior error covariance matrix, <span class="inline-formula"><i>F</i>(<strong><em>x</em></strong>)</span> is the simulation of observations <span class="inline-formula"><strong><em>y</em></strong></span> by the GEOS-Chem model, <span class="inline-formula"><strong>S</strong><sub>O</sub></span> is the observational error covariance matrix, and <span class="inline-formula"><i>γ</i></span> is a regularization factor <span class="cit" id="xref_paren.85">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Brasseur and Jacob</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. The variances in <span class="inline-formula"><strong>S</strong><sub>O</sub></span> are underestimated because of correlation in the observational error that is missing in the diagonal formulation of <span class="inline-formula"><strong>S</strong><sub>O</sub></span> and is difficult to quantify. We use <span class="inline-formula"><i>γ</i></span> to scale the original diagonal <span class="inline-formula"><strong>S</strong><sub>O</sub></span> to get an optimal covariance matrix to be used in the inversion. <span class="cit" id="xref_text.86"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> showed in an observing system simulation experiment (OSSE) for inversion of methane satellite data that a regularization factor <span class="inline-formula"><i>γ</i>=0.05</span> adjusts the variances optimally and prevents overfitting. This was done by calculating the likelihood at <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M85" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mi mathvariant="bold-italic">x</mi><mo stretchy="true" mathvariant="normal">^</mo></mover></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="ddf253985ab4585c97f904312635fb93"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00023.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00023.png"></image></svg></span></span> for a range of values of <span class="inline-formula"><i>γ</i></span>. Diagnosis of overfit and optimization of <span class="inline-formula"><i>γ</i></span> is readily done in an OSSE such as in <span class="cit" id="xref_text.87"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> where the “true” solution is known. Here we find that using <span class="inline-formula"><i>γ</i>=1</span> (as in the pure Bayesian statement of the optimization problem) produces checkerboard patterns in the solution that are likely spurious. We choose <span class="inline-formula"><i>γ</i>=0.05</span> consistent with <span class="cit" id="xref_text.88"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> for our base inversion as providing the best balance between prior and observational terms in the posterior value of the cost function. We examine the sensitivity to the choice of <span class="inline-formula"><i>γ</i></span> by conducting a sensitivity inversion with <span class="inline-formula"><i>γ</i>=0.1</span>.</p> <p id="d1e2209">Further balancing of the cost function is needed because the global OH concentration and its interannual variability are represented by only seven state vector elements, while the emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M92" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="c0e54b38680d4ffcb3c58d12cd44390a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00024.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00024.png"></image></svg></span></span> grid are represented by 1009 elements. To provide equal weight to OH and emissions for explaining global methane trends, we increase the weight of the OH terms in the cost function (through the OH components of <span class="inline-formula"><strong>S</strong><sub>a</sub></span>) by the ratio of the number of state vector elements <span class="inline-formula">1009∕7</span> so that from a cost-function perspective, a change in OH and global methane emissions is equally expensive. The sensitivity inversion assuming 10 % prior error standard deviation on OH instead of 3 % is equivalent to decreasing this weighting by a factor of 11.</p> <p id="d1e2255">The GEOS-Chem forward model <span class="inline-formula"><strong><em>y</em></strong>=<i>F</i>(<strong><em>x</em></strong>)</span> relating methane column concentrations <span class="inline-formula"><strong><em>y</em></strong></span> to the state vector <span class="inline-formula"><strong><em>x</em></strong></span> is essentially linear. There is a small nonlinearity from the optimization of OH concentrations because changes in the methane concentrations affect the loss rate <span class="cit" id="xref_paren.89">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx35" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Houweling et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx35" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>, which we neglect because changes in methane concentrations are small, and methane is well mixed globally. We therefore express the forward model as <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M98" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi>F</mi><mo>(</mo><mi mathvariant="bold-italic">x</mi><mo>)</mo><mo>=</mo><mi mathvariant="bold">K</mi><mi mathvariant="bold-italic">x</mi><mo>+</mo><mi mathvariant="bold-italic">c</mi></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="70pt" height="12pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1a5526f57c6e5db74177dbd8c9a9a0b6"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00025.svg" width="100%" height="12pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00025.png"></image></svg></span></span>, where <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M99" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="bold">K</mi><mo>=</mo><mo>∂</mo><mi>y</mi><mo>/</mo><mo>∂</mo><mi>x</mi></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="56pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="ce8a489217665f8846f259ebd4865fde"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00026.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00026.png"></image></svg></span></span> is the Jacobian matrix of the model, and <span class="inline-formula"><strong><em>c</em></strong></span> is an initialization constant (January 2009 concentrations taken from <span class="cit" id="xref_altparen.90"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a></span>). Replacing <span class="inline-formula"><i>F</i>(<strong><em>x</em></strong>)=<strong>K</strong><strong><em>x</em></strong></span> in Eq. (<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2</a>) and subtracting the initialization constant <span class="inline-formula"><strong><em>c</em></strong></span> from the observations, the minimization problem <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M103" display="inline" overflow="scroll" dspmath="mathml"><mrow><mtext>d</mtext><mi>J</mi><mo>(</mo><mi mathvariant="bold-italic">x</mi><mo>)</mo><mo>/</mo><mtext>d</mtext><mi mathvariant="bold-italic">x</mi><mo>=</mo><mn mathvariant="bold">0</mn></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="67pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="cff4ea04840881de99c885c839363112"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00027.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00027.png"></image></svg></span></span> has an analytical solution for the optimal posterior solution <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M104" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mi mathvariant="bold-italic">x</mi><mo mathvariant="normal" stretchy="true">^</mo></mover></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="4c8904893e18fe746c2c57eae2692360"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00028.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00028.png"></image></svg></span></span> <span class="cit" id="xref_paren.91">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rodgers</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2000</a>)</span>: </p><div class="disp-formula" content-type="numbered" id="Ch1.E3"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M105" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(3)</mtext></mtd><mtd><mrow> <mover accent="true"> <mi mathvariant="bold-italic">x</mi> <mo stretchy="true" mathvariant="normal">^</mo> </mover> <mo>=</mo> <msub> <mi mathvariant="bold-italic">x</mi> <mtext>a</mtext> </msub> <mo>+</mo> <msub> <mi mathvariant="bold">S</mi> <mtext>a</mtext> </msub> <msup> <mi mathvariant="bold">K</mi> <mi>T</mi> </msup> <msup> <mfenced open="(" close=")"> <mrow> <msub> <mi mathvariant="bold">KS</mi> <mtext>a</mtext> </msub> <msup> <mi mathvariant="bold">K</mi> <mi>T</mi> </msup> <mo>+</mo> <mstyle displaystyle="true"> <mfrac style="display"> <mrow> <msub> <mi mathvariant="bold">S</mi> <mtext>O</mtext> </msub> </mrow> <mi mathvariant="italic">γ</mi> </mfrac> </mstyle> </mrow> </mfenced> <mrow> <mo>-</mo> <mn mathvariant="normal">1</mn> </mrow> </msup> <mfenced open="(" close=")"> <mrow> <mi mathvariant="bold-italic">y</mi> <mo>-</mo> <mi mathvariant="bold">K</mi> <msub> <mi mathvariant="bold-italic">x</mi> <mtext>a</mtext> </msub> </mrow> </mfenced> <mo>.</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="245pt" height="31pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="99482290ee614656caadd62ee0794d7a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_2.svg" width="100%" height="31pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_2.png"></image></svg></div></div><p id="d1e2255-3"> The posterior error covariance matrix <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M106" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mi mathvariant="bold">S</mi><mo mathvariant="normal" stretchy="true">^</mo></mover></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="10pt" height="13pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f3494e86a20a33839318be9bcba8d35f"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00029.svg" width="100%" height="13pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00029.png"></image></svg></span></span> describing the error statistics of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M107" display="inline" overflow="scroll" dspmath="mathml"><mover accent="true"><mi mathvariant="bold-italic">x</mi><mo mathvariant="normal" stretchy="true">^</mo></mover></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1d174682363be11d95ddadf722754515"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00030.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00030.png"></image></svg></span></span> is given by </p><div class="disp-formula" content-type="numbered" id="Ch1.E4"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M108" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(4)</mtext></mtd><mtd><mrow> <mover accent="true"> <mi mathvariant="bold">S</mi> <mo mathvariant="normal" stretchy="true">^</mo> </mover> <mo>=</mo> <msup> <mfenced open="(" close=")"> <mrow> <mi mathvariant="italic">γ</mi> <msup> <mi mathvariant="bold">K</mi> <mi>T</mi> </msup> <msubsup> <mi mathvariant="bold">S</mi> <mtext>O</mtext> <mrow> <mo>-</mo> <mn mathvariant="normal">1</mn> </mrow> </msubsup> <mi mathvariant="bold">K</mi> <mo>+</mo> <msubsup> <mi mathvariant="bold">S</mi> <mtext>a</mtext> <mrow> <mo>-</mo> <mn mathvariant="normal">1</mn> </mrow> </msubsup> </mrow> </mfenced> <mrow> <mo>-</mo> <mn mathvariant="normal">1</mn> </mrow> </msup> <mo>,</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="162pt" height="24pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="bc9fd48e079335ed57e6b2d3933c8ebc"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_3.svg" width="100%" height="24pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_3.png"></image></svg></div></div><p id="d1e2255-5"> and the averaging kernel matrix (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M109" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="bold">A</mi><mo>=</mo><mo>∂</mo><mover accent="true"><mi mathvariant="bold-italic">x</mi><mo stretchy="true" mathvariant="normal">^</mo></mover><mo>/</mo><mo>∂</mo><mi mathvariant="bold-italic">x</mi></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="57pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="3523c94a197c24b7b3bd2ee8c50f21cc"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00031.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00031.png"></image></svg></span></span>) defining the sensitivity of the solution to the true state is given by </p><div class="disp-formula" content-type="numbered" id="Ch1.E5"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M110" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(5)</mtext></mtd><mtd><mrow> <mi mathvariant="bold">A</mi> <mo>=</mo> <msub> <mi mathvariant="bold">S</mi> <mi mathvariant="bold">a</mi> </msub> <msup> <mi mathvariant="bold">K</mi> <mi>T</mi> </msup> <msup> <mfenced open="(" close=")"> <mrow> <msub> <mi mathvariant="bold">KS</mi> <mtext>a</mtext> </msub> <msup> <mi mathvariant="bold">K</mi> <mi>T</mi> </msup> <mo>+</mo> <mstyle displaystyle="true"> <mfrac style="display"> <mrow> <msub> <mi mathvariant="bold">S</mi> <mtext>O</mtext> </msub> </mrow> <mi mathvariant="italic">γ</mi> </mfrac> </mstyle> </mrow> </mfenced> <mrow> <mo>-</mo> <mn mathvariant="normal">1</mn> </mrow> </msup> <mo>.</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="176pt" height="31pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1eba6a9937ed49e80d7b9ac50d448bfb"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_4.svg" width="100%" height="31pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_4.png"></image></svg></div></div><p id="d1e2255-7"> The trace of the averaging kernel matrix defines the degrees of freedom for signal (DOFS) of the inversion, that is the number of pieces of information on the state vector that can be gained from the observing system.</p> <p id="d1e2643">The analytical solution as described by Eqs. (<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">3</a>)–(<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">5</a>) requires the explicit construction of the Jacobian matrix <span class="inline-formula"><strong>K</strong></span> characterizing the GEOS-Chem model. We do this column by column, with GEOS-Chem simulations perturbing each element of the state vector independently. This is readily achievable, even for 2025 state vector elements as a massively parallel computation. Sparse matrix algebra is used where possible in solving Eqs. (<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">3</a>)–(<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">5</a>), taking advantage of the diagonal structure of the error covariance matrices.</p> <p id="d1e2661">The analytical solution to the Bayesian optimization problem requires assumption of Gaussian errors, but this allows for the possibility of negative values of state vector elements. Negative emissions could conceivably be attributed to locally strong soil uptake or oxidation by Cl atoms but may also be unphysical <span class="cit" id="xref_paren.92">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx54" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx54" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span>. We can enforce positivity in the Bayesian solution by optimizing for <span class="inline-formula">ln (<strong><em>x</em></strong>)</span> instead of <span class="inline-formula"><strong><em>x</em></strong></span>, with normal Gaussian errors specified for <span class="inline-formula">ln (<strong><em>x</em></strong>)</span> (corresponding to lognormal errors for <span class="inline-formula"><strong><em>x</em></strong></span>). The model is then nonlinear, so that the solution and the corresponding error statistics must be found iteratively with an updated Jacobian matrix <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M116" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="bold">K</mi><mi>N</mi><mo>′</mo></msubsup><mo>=</mo><mo>∂</mo><mi mathvariant="bold-italic">y</mi><mo>/</mo><mo>∂</mo><mi>ln</mi><mi mathvariant="bold-italic">x</mi></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="74pt" height="15pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="d1e6f85c29850a047c722423973470e6"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00032.svg" width="100%" height="15pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00032.png"></image></svg></span></span> at each iteration <span class="inline-formula"><i>N</i></span>. This recomputation is immediate using the previously derived Jacobian matrix <span class="inline-formula"><strong>K</strong></span> for the linear problem, since the individual scalar elements <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M119" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∂</mo><msub><mi>y</mi><mi>i</mi></msub><mo>/</mo><mo>∂</mo><mi>ln</mi><mo>(</mo><msub><mi>x</mi><mi>i</mi></msub><mo>)</mo></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="58pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f49d158482275cf30d84776703ec6738"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00033.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00033.png"></image></svg></span></span> of <span class="inline-formula"><strong>K</strong><sup>′</sup></span> are related to those of <span class="inline-formula"><strong>K</strong></span> by <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M122" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∂</mo><msub><mi>y</mi><mi>i</mi></msub><mo>/</mo><mo>∂</mo><mi>ln</mi><mo>(</mo><msub><mi>x</mi><mi>j</mi></msub><mo>)</mo><mo>=</mo><msub><mi>x</mi><mi>j</mi></msub><mo>∂</mo><msub><mi>y</mi><mi>i</mi></msub><mo>/</mo><mo>∂</mo><msub><mi>x</mi><mi>j</mi></msub></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="120pt" height="16pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f4db7b39172f9bf10900eb02c8edac56"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00034.svg" width="100%" height="16pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00034.png"></image></svg></span></span>. Thus only a simple scaling of the linear Jacobian matrix is required at each iteration. This conversion to log space is done only for the emissions component of <span class="inline-formula"><strong><em>x</em></strong></span>. Emission trends and global OH concentrations are still optimized with normal error distributions, and no scaling is applied to those rows of the Jacobian.</p> <p id="d1e2857">Optimizing emissions in log space means that the best posterior estimate is for the median of emissions instead of the mean. The mean and the median of the lognormal distribution are not equal, so results cannot be summed over grid<span id="page7865"></span> squares to provide a best estimate of the mean. For this reason, analysis of aggregate and global emissions and sinks will be done with the inversion using normal errors.</p> <p id="d1e2860">The iterative solution for the inverse problem with lognormal errors is obtained with the Levenberg–Marquardt method <span class="cit" id="xref_paren.93">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Rodgers</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2000</a>)</span> for each iteration <span class="inline-formula"><i>N</i></span>: </p><span id="Ch1.E6" class="equationLink"></span><div class="disp-formula" content-type="numbered" specific-use="align"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M125" display="block" overflow="scroll" dspmath="mathml"><mtable columnalign="left" displaystyle="true"><mlabeledtr><mtd><mtext>(6)</mtext></mtd><mtd><mrow><mstyle class="stylechange" displaystyle="true"></mstyle><msub><msup><mi mathvariant="bold-italic">x</mi><mo mathvariant="bold">′</mo></msup><mrow><mi>N</mi><mo>+</mo><mn mathvariant="normal">1</mn></mrow></msub><mo>=</mo></mrow></mtd><mtd><mrow><mstyle displaystyle="true" class="stylechange"></mstyle><msub><msup><mi mathvariant="bold-italic">x</mi><mo mathvariant="bold">′</mo></msup><mi>N</mi></msub><mo>+</mo><msup><mfenced open="(" close=")"><mrow><mo>(</mo><mn mathvariant="normal">1</mn><mo>+</mo><mi mathvariant="italic">κ</mi><mo>)</mo><msubsup><msup><mi mathvariant="bold">S</mi><mo>′</mo></msup><mtext>A</mtext><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup><mo>+</mo><mi mathvariant="italic">γ</mi><msubsup><msup><mi mathvariant="bold">K</mi><mo>′</mo></msup><mi>N</mi><mi>T</mi></msubsup><msubsup><mi mathvariant="bold">S</mi><mtext>O</mtext><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup><msubsup><msup><mi mathvariant="bold">K</mi><mo>′</mo></msup><mi>N</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></mfenced><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></mtd></mlabeledtr><mtr><mtd><mstyle class="stylechange" displaystyle="true"></mstyle></mtd><mtd><mrow><mstyle class="stylechange" displaystyle="true"></mstyle><mfenced close=")" open="("><mrow><mi mathvariant="italic">γ</mi><msubsup><msup><mi mathvariant="bold">K</mi><mo>′</mo></msup><mi>N</mi><mi>T</mi></msubsup><msubsup><mi mathvariant="bold">S</mi><mtext>O</mtext><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup><mfenced close=")" open="("><mrow><mi mathvariant="bold-italic">y</mi><mo>-</mo><mi mathvariant="bold">K</mi><msub><mi mathvariant="bold-italic">x</mi><mi>N</mi></msub></mrow></mfenced><mo>-</mo><msup><msubsup><mi mathvariant="bold">S</mi><mtext>A</mtext><mo>′</mo></msubsup><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mfenced open="(" close=")"><mrow><msub><msup><mi mathvariant="bold-italic">x</mi><mo mathvariant="bold">′</mo></msup><mi>N</mi></msub><mo>-</mo><msubsup><mi mathvariant="bold-italic">x</mi><mtext>A</mtext><mo mathvariant="bold">′</mo></msubsup></mrow></mfenced></mrow></mfenced><mo>,</mo></mrow></mtd></mtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="274pt" height="49pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="c54e75a6247bf842daff29068b91d2a5"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_6.svg" width="100%" height="49pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_6.png"></image></svg></div></div><p id="d1e2860-3"> where <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M126" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi mathvariant="bold-italic">x</mi><mo mathvariant="bold">′</mo></msup><mo>=</mo><mi>ln</mi><mi mathvariant="bold-italic">x</mi></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="41pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="c48d208a3fc27f06ad4275aff2721507"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00035.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00035.png"></image></svg></span></span>, the initial guess <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M127" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><msup><mi mathvariant="bold-italic">x</mi><mo mathvariant="bold">′</mo></msup><mn mathvariant="normal">0</mn></msub></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="17pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="43c5bcbe46c419657cbab3dea5061393"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00036.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00036.png"></image></svg></span></span> is the prior estimate, and <span class="inline-formula"><i>κ</i></span> is a coefficient for the iterative approach to the solution that is set to 100 to start and is gradually decreased as the solution is approached. The prior error covariance matrix <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M129" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="bold">S</mi><mtext>a</mtext><mo>′</mo></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="14pt" height="14pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="ff1174f81f572b5d28df06b84531ef65"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00037.svg" width="100%" height="14pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00037.png"></image></svg></span></span> (diagonal elements <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M130" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi>s</mi><mtext>A</mtext><mo>′</mo></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="15pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="e92f41f676a7f12936734ae2d06cce85"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00038.svg" width="100%" height="15pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00038.png"></image></svg></span></span>) defining error variances for <span class="inline-formula">ln <strong><em>x</em></strong><sub>a</sub></span> is derived from the previously described prior error covariance matrix <span class="inline-formula"><strong>S</strong><sub>a</sub></span> (diagonal elements <span class="inline-formula"><i>s</i><sub>A</sub></span>) by scaling the error variances for the individual elements: </p><div class="disp-formula" content-type="numbered" id="Ch1.E7"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M134" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(7)</mtext></mtd><mtd><mrow> <msubsup> <mi>s</mi> <mtext>A</mtext> <mo>′</mo> </msubsup> <mo>=</mo> <msup> <mfenced close=")" open="("> <mstyle displaystyle="true"> <mfrac style="display"> <mrow> <mi>ln</mi> <mfenced close=")" open="("> <mstyle displaystyle="false"> <mfrac style="text"> <mrow> <msub> <mi>x</mi> <mtext>A</mtext> </msub> <mo>+</mo> <msqrt> <mrow> <msub> <mi>s</mi> <mtext>A</mtext> </msub> </mrow> </msqrt> </mrow> <mrow> <msub> <mi>x</mi> <mtext>A</mtext> </msub> </mrow> </mfrac> </mstyle> </mfenced> <mo>+</mo> <mfenced open="|" close="|"> <mrow> <mi>ln</mi> <mfenced close=")" open="("> <mstyle displaystyle="false"> <mfrac style="text"> <mrow> <msub> <mi>x</mi> <mtext>A</mtext> </msub> <mo>-</mo> <msqrt> <mrow> <msub> <mi>s</mi> <mtext>A</mtext> </msub> </mrow> </msqrt> </mrow> <mrow> <msub> <mi>x</mi> <mtext>A</mtext> </msub> </mrow> </mfrac> </mstyle> </mfenced> </mrow> </mfenced> </mrow> <mn mathvariant="normal">2</mn> </mfrac> </mstyle> </mfenced> <mn mathvariant="normal">2</mn> </msup> <mo>.</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="228pt" height="51pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f11b0146272fe41188457f4fb7382fee"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_5.svg" width="100%" height="51pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_5.png"></image></svg></div></div> </div><div class="sec"><h2 id="Ch1.S2.SS6"><span class="label">2.6</span> Error correlations between global estimates of sources and sinks</h2> <p id="d1e3251">Inversion results for the spatial distributions of emissions and trends on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M135" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="98e55ffe225862377dd7c0354d4117db"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00039.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00039.png"></image></svg></span></span> grid are mainly informed by local and regional patterns of methane concentration. However, implied inversion results for the global methane emission and its trend may be significantly correlated with those for the global tropospheric OH concentration and its trend. Some separation is expected because sources of methane have a different spatial and seasonal imprint on the global methane distribution than the OH sink <span class="cit" id="xref_paren.94">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>, but it is important to quantify the error correlation, i.e., the extent to which adjustments to the global methane emission and its trend may be aliased by adjustments to the global OH concentration and its trend.</p> <p id="d1e3277">To do this we reduce the dimensionality of the inverse analysis by collapsing global emissions and trends into one state vector element each. Following <span class="cit" id="xref_text.95"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Calisesi et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2005</a>)</span>, if the state vector can be transformed using a summation matrix <span class="inline-formula"><strong>W</strong></span> as </p><div class="disp-formula" content-type="numbered" id="Ch1.E8"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M137" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(8)</mtext></mtd><mtd><mrow> <msub> <mi mathvariant="bold-italic">x</mi> <mtext>red</mtext> </msub> <mo>=</mo> <mi mathvariant="bold">W</mi> <mi mathvariant="bold-italic">x</mi> <mo>,</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="92pt" height="13pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1b55cd4c7ae9be109c3e4221494913d3"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_6.svg" width="100%" height="13pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_6.png"></image></svg></div></div><p id="d1e3277-3"> then the averaging kernel matrix of the reduced system (<span class="inline-formula"><strong>A</strong><sub>red</sub></span>) is given by </p><div class="disp-formula" content-type="numbered" id="Ch1.E9"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M139" display="block" overflow="scroll" dspmath="mathml"><mtable><mlabeledtr><mtd><mtext>(9)</mtext></mtd><mtd><mrow> <msub> <mi mathvariant="bold">A</mi> <mtext>red</mtext> </msub> <mo>=</mo> <msup> <mi mathvariant="bold">WAW</mi> <mo>*</mo> </msup> <mo>,</mo> </mrow></mtd></mlabeledtr></mtable></math><div><svg xmlns:svg="http://www.w3.org/2000/svg" width="107pt" height="13pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="eae44a26bb2fa87efa37da1954dbf08a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_7.svg" width="100%" height="13pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-e_7.png"></image></svg></div></div><p id="d1e3277-5"> where <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M140" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi mathvariant="bold">W</mi><mo>*</mo></msup><mo>=</mo><mo>(</mo><msup><mi mathvariant="bold">W</mi><mi>T</mi></msup><mi mathvariant="bold">W</mi><msup><mo>)</mo><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><msup><mi mathvariant="bold">W</mi><mi>T</mi></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="87pt" height="15pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="88fa83d686f25c98253f8564e326b069"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00040.svg" width="100%" height="15pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00040.png"></image></svg></span></span> is the generalized pseudo-inverse of <span class="inline-formula"><strong>W</strong></span>. Our original state vector <span class="inline-formula"><strong><em>x</em></strong></span> in this case includes mean 2010–2015 emissions and their linear trends on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M143" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="3e15d886169fb6f4ef2eaaea1fe1ca24"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00041.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00041.png"></image></svg></span></span> grid and the global mean tropospheric OH concentration for 2010–2015 and its linear trend. Again, the minor sinks in Table 1 are not optimized and are maintained instead at their prior values. We apply the summation matrix <span class="inline-formula"><strong>W</strong></span> to the emission terms and thus reduce the state vector to four elements defining the global methane budget (global mean emission, global mean OH concentration, global emission trend, global OH trend). The off-diagonal terms of the reduced averaging kernel matrix <span class="inline-formula"><strong>A</strong><sub>red</sub></span> then measure the extent to which differences relative to the true state are aliased between sources and sinks in the optimization of this global budget. The advantage of this summation approach, as compared to a global inversion including just four elements, is that the distribution of methane emissions and its trends is still optimized.</p> <div class="fig" id="Ch1.F3"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f03-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f03" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f03-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f03-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f03.jpg" data-width="2067" data-height="2079"></a><div class="caption"><p id="d1e3430"><strong class="caption-number">Figure 3</strong>Comparisons of observed methane concentrations to the GEOS-Chem forward model using either prior or posterior (optimized) estimates of 2010–2015 emissions and OH concentrations. Panels <strong>(a)</strong> and <strong>(b)</strong> show differences between the model and GOSAT observations for 2010–2015 means on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M146" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="0d816f66ded6e01c1410546bec8054b7"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00042.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00042.png"></image></svg></span></span> grid. Panels <strong>(c)</strong> and <strong>(d)</strong> show the monthly time series of the differences averaged over latitude bands. Panels <strong>(e–g)</strong> show independent 2010–2015 comparisons to global observations from NOAA surface stations, HIPPO aircraft meridional cross sections over the Pacific (2010 and 2011, with the model sampled along the flight tracks), and TCCON. Reduced major axis (RMA) regressions are as shown along with the 1 : 1 line (in grey). HIPPO observations are averaged over GEOS-Chem grid cells. The NOAA surface stations and HIPPO aircraft measure local methane dry-air mole fractions, while TCCON measures column-averaged dry-air mole factions. We apply the same latitudinal and seasonal corrections to TCCON that we applied to GOSAT.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f03.jpg" target="_blank">Download</a></p></div> </div></div><span class="section2-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="sec" id="section3"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section3 .co-arrow-open,.section3-content" data-show="#section3 .co-arrow-closed,.section3-mobile-bottom-border"><div id="Ch1.S3" class="h1"><span class="label">3</span> Results and discussion<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section3-content show-no-js hide-on-mobile-soft"><p id="d1e3484">We conduct an ensemble of inversions to characterize the sensitivity of the solution to different assumptions made in the formulation of the inverse problem. Our base inversion optimizes annual mean emissions with normal error distributions and seasonal background correction to the GOSAT–model difference as discussed above. To test whether choices in the regularization and cost-function construction affect our conclusions, we also conduct inversions with (1) lognormal error distributions for emissions, (2) a regularization factor <span class="inline-formula"><i>γ</i></span> of 0.1 instead of 0.05, (3) no seasonal background correction to the model–GOSAT difference, (4) a 10 % error standard deviation on the global OH concentration instead of 3 %, (5) optimization of a linear trend in global OH concentration instead of year-to-year variability, assuming 10 % error standard deviation for mean OH and 5 % for the 2010–2015 trend, (6) no interannual variability in prior emission estimates, and (7, 8) seasonally resolved emission optimization including seasonal correction and not including seasonal correction (see Appendix B). All inversions produce consistent results, and we will focus our main presentation on the base inversion, bringing in the sensitivity inversions to illustrate the spread of results and to address specific issues.</p><p id="d1e3494">Before presenting results from the inversion, we compare the posterior solution to observations to show that the inversion accomplishes its task of providing an improved forward model fit to observations. Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">3</a>a–d show the improvement in the GEOS-Chem comparison to the GOSAT data when using posterior vs. prior emissions, emission trends, and OH concentrations. As expected for a successful inversion, the posterior values provide a better fit to the observations. The inversion corrects prior underestimates over tropical regions and an overestimate over China. It also fits the observed 2010–2015 trend in methane concentrations and its latitudinal distribution, while the prior model underestimated the growth rate, especially in 2014–2015. It does not fully<span id="page7866"></span> correct the prior bias in the Arctic because GOSAT observations north of 60<span class="inline-formula"><sup>∘</sup></span> N are not used in the inversion.</p><p id="d1e3508">Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">3</a> also shows independent evaluation of the inversion results with background observations from the NOAA cooperative flask sampling network (<span class="uri"><a href="https://esrl.noaa.gov/gmd/ccgg/flask.php" target="_blank">https://esrl.noaa.gov/gmd/ccgg/flask.php</a></span>, last access: 16 February 2018), the HIPPO aircraft campaigns across the Pacific and Atlantic (legs III–V; <span class="uri"><a href="https://hippo.ornl.gov/" target="_blank">https://hippo.ornl.gov/</a></span>, last access: 27 April 2019; <span class="cit" id="xref_altparen.96"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx105" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wofsy</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx105" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a></span>), and the Total Carbon Column Observing Network (TCCON; <span class="uri"><a href="https://tccondata.org/" target="_blank">https://tccondata.org/</a></span>, last access: 27 April 2019; <span class="cit" id="xref_altparen.97"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx107" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wunch et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx107" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2011</a></span>). These observations are mainly of the seasonal/latitudinal methane background and are not used in the inversion. The background is already well simulated in the prior estimate, and the posterior simulation does not degrade this agreement.</p><div class="fig" id="Ch1.F4"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f04-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f04" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f04-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f04-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f04.jpg" data-width="2067" data-height="1600"></a><div class="caption"><p id="d1e3532"><strong class="caption-number">Figure 4</strong>Optimization of the global distribution of mean 2010–2015 methane emissions using GOSAT observations. Prior emissions are in <strong>(a)</strong> (see breakdown in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2</a>). Panel <strong>(b)</strong> shows averaging kernel sensitivities for the base inversion (diagonal elements of the averaging kernel matrix), with the degrees of freedom for signal (DOFS; trace of the averaging kernel matrix) in the legend. Panels <strong>(c, d)</strong> show the posterior emissions from the base inversion and the associated ratios between posterior and prior emissions. Grey grid cells (for example in North Africa and Australia) indicate small negative posterior emissions. Panels <strong>(e, f)</strong> show the same but for the inversion assuming lognormal prior errors, which does not allow for negative posterior emissions.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f04.jpg" target="_blank">Download</a></p></div><div class="sec"><h2 id="Ch1.S3.SS1"><span class="label">3.1</span> Spatial distribution and source attribution of methane emissions</h2> <p id="d1e3562"><span id="page7867"></span>Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">4</a> shows the global distribution of mean 2010–2015 posterior emissions from the base inversion and from the sensitivity inversion assuming lognormal errors in the prior emission estimates. Correction patterns are very similar between the two inversions. Small negative emissions are found in the base inversion for 6 of the 1009 optimized grid cells. The inversion assuming lognormal errors does not allow these negative emissions. Downward corrections tend to be smaller in the inversion assuming lognormal errors, while positive corrections are larger and more concentrated in a few grid cells, as would be expected from the different shapes of the error standard deviation distributions.</p> <p id="d1e3568">Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">4</a>b shows the diagonal terms of the averaging kernel matrix for the base inversion (averaging kernel sensitivities), measuring the ability of the observations to constrain the inversion. The trace of the averaging kernel matrix (DOFS <span class="inline-formula">=</span> 128) measures the number of independent pieces of information constrained by the inversion. A Bayesian inversion without correcting for overfit (<span class="inline-formula"><i>γ</i>=1</span> in Eq. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">3</a>) would erroneously produce much higher DOFS. We find that the inversion provides strong constraints on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M151" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="b2b35067ef33da1da2d273628a98942f"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00043.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00043.png"></image></svg></span></span> grid for source regions in East Asia, central Africa, and South America. Averaging kernel sensitivities are generally weaker over North America and in Europe, indicating that the inversion provides more diffuse spatial information in these regions.</p> <p id="d1e3614">We find that the EDGAR v4.3.2 inventory prominently overestimates anthropogenic emissions over eastern China, likely from coal production, and around the Persian Gulf, likely from oil and gas production. The finding of an EDGAR overestimate in China is consistent with previous global inversions of GOSAT data using EDGAR v4.1, v4.2, and v4.2FT2010 as prior estimates <span class="cit" id="xref_paren.98">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx56" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Monteil et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx56" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx90" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Thompson et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx90" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Alexe et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx64" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Pandey et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx64" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span> and a regional inversion using EDGAR v4.3.2 <span class="cit" id="xref_paren.99">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span>. The overestimate of coal mining emissions may be because standard IPCC emission factors used by EDGAR v4.2 were too high for Chinese coal mines, and recovery of coal mine methane is not sufficiently taken into account <span class="cit" id="xref_paren.100">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx69" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Peng et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx69" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. Emission factors were decreased in EDGAR v4.3.2 <span class="cit" id="xref_paren.101">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx40" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Janssens-Maenhout et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx40" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span>, but we still find an overestimate. We find that EDGAR underestimates emissions over Japan and Southeast Asia, where rice cultivation is the largest anthropogenic source, but there are also large wetland emissions. There are also large corrections in wetland areas of central Africa, South America, and North America.</p> <p id="d1e3629"><span id="page7868"></span>We do not find large correction factors over the United States, except for the southeastern coast which is likely due to an overestimate of methane emissions from coastal wetlands in the prior WetCHARTs inventory. This overestimate of US coastal wetland emissions in WetCHARTs is consistent with a previous inversion of aircraft observations over the Southeast United States by <span class="cit" id="xref_text.102"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx82" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sheng et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx82" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx82" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>)</span> and may be explained by low soil organic carbon in these ecosystems <span class="cit" id="xref_paren.103">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx33" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Holmquist et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx33" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> and/or the overestimated impacts of partial wetland land-cover classes predominant in the southeastern United States <span class="cit" id="xref_paren.104">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx47" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Lehner and Döll</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx47" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2004</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Bloom et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. Previous inversions found factor of 2 underestimates of EDGAR v4.2 emissions of the South Central United States <span class="cit" id="xref_paren.105">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx53" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx53" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2013</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>, but we do not find such an underestimate here and attribute this to our use of the gridded version of the US EPA inventory as prior estimate <span class="cit" id="xref_paren.106">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. EDGAR v4.2 allocated oil and gas emissions mainly according to population, which greatly underestimates emissions in oil and gas production regions in the South Central United States <span class="cit" id="xref_paren.107">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Maasakkers et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>.</p> <div class="fig" id="Ch1.F5"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f05-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f05" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f05-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f05-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f05.png" data-width="2067" data-height="1680"></a><div class="caption"><p id="d1e3658"><strong class="caption-number">Figure 5</strong>Global methane emissions by source type in the prior estimate for the inversion (Table 1, “other” includes fossil fuel combustion, industrial processes, and agricultural field burning) and in the posterior estimate. Values are 2010–2015 means. The attribution to source types in the posterior estimate is done by assuming that the relative contributions of different source types in individual <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M152" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="bae1fdfe92ea6a0ea8424f5c9e8c1ab9"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00044.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00044.png"></image></svg></span></span> grid cells are correct in the prior estimate. Posterior estimates are from the base inversion, and error bars show the ranges of results from the inversion ensemble.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f05.png" target="_blank">Download</a></p></div> <p id="d1e3687">Improved estimates of global methane emissions for the individual source types of Table 1 can be inferred from our results by assuming that the relative contributions from different source types in a given <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M153" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="5ab6ac6fc27e76ac8098350840da2f31"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00045.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00045.png"></image></svg></span></span> grid cell are correct in the prior inventory. The global posterior estimate for a given source type is then obtained by applying the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M154" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="95edb37851f0a657505408b81f77e202"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00046.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00046.png"></image></svg></span></span> posterior / prior ratios from Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">4</a> to the distribution of source types in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2</a>. Results in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">5</a> indicate little change to 2010–2015 average emissions compared to the global prior inventory by source type, even though there are large regional reallocations. Coal mining emissions decrease by 29 %, mainly due to China, and rice cultivation and livestock increase by 15 % and 8 % respectively, mainly driven by the tropics.</p> <p id="d1e3736">There has been particular interest in quantifying emissions from oil and gas exploitation because of the potential for large reductions of these emissions through simple control measures <span class="cit" id="xref_paren.108">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx109" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zavala-Araiza et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx109" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Alvarez et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. The EDGAR v4.3.2 national oil and gas emission totals can differ greatly from the national (spatially unresolved) totals reported by individual countries to the United Nations Framework Convention on Climate Change <span class="cit" id="xref_paren.109">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx96" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">UNFCCC</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx96" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. This is shown in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">6</a> with national oil and gas emissions from the top 10 countries in either the EDGAR v4.3.2 or UNFCCC inventories. We can estimate national oil and gas emission totals from our inversion by again assuming that the relative contributions of oil and gas to total emissions in individual <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M155" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="c427b05d9f73d00006533d3d7d721429"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00047.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00047.png"></image></svg></span></span> grid cells are correct and by further mapping the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M156" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="5003dbb2199a3a61c12a6b65516f55e1"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00048.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00048.png"></image></svg></span></span> correction factors to the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M157" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.1</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">0.1</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="a57a7e8729ddfa4fbbc612845a227cbf"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00049.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00049.png"></image></svg></span></span> EDGAR emission grid. The emission-weighted scaling factor is then used with the national oil and gas totals reported by EDGAR. Russia is the largest national source, but the inversion is limited in its ability to constrain oil and gas emissions there because a third of these emissions are north of 60<span class="inline-formula"><sup>∘</sup></span> N in EDGAR v4.3.2 (Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2</a>).</p> <div class="fig" id="Ch1.F6"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f06-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f06" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f06-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f06-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f06.png" data-width="1952" data-height="2471"></a><div class="caption"><p id="d1e3821"><strong class="caption-number">Figure 6</strong>National estimates of methane emissions from the oil and gas industry for countries in the top 10 of either the EDGAR v4.3.2 or UNFCCC inventories. Values reported by individual countries to the UNFCCC for 2012 (Annex I countries) or the closest year (non-Annex I countries: Nigeria (1994), Venezuela (1999), Algeria (2000), Iran (2000), India (2010), Saudi Arabia (2010), and China (2012)) are compared to 2012 emissions from EDGAR v4.3.2 national oil and gas totals and to the posterior values from our base inversion as described in the text. Black lines are ranges for the ensemble of inversions. A large part of Russian emissions are too far north to be effectively constrained by the inversion.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f06.png" target="_blank">Download</a></p></div> <div class="fig" id="Ch1.F7"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f07-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f07" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f07-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f07-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f07.png" data-width="2067" data-height="1343"></a><div class="caption"><p id="d1e3832"><strong class="caption-number">Figure 7</strong>2010–2015 methane emission trends and global tropospheric OH trends as optimized by the inversion of GOSAT data and corresponding averaging kernel sensitivities (diagonal terms of the average kernel matrix). The degrees of information for signal or DOFS (trace of the averaging kernel matrix) is shown inset. Panel <strong>(c)</strong> gives the global attribution of the emission trends to individual source types, with ranges from the inversion ensemble. Shaded sections of the bars indicate the contribution from the tropics (24<span class="inline-formula"><sup>∘</sup></span> S–24<span class="inline-formula"><sup>∘</sup></span> N). The vertical bars in the OH trend panel are the posterior error standard deviations from the base inversion. The 2010–2015 decreasing trend in OH concentrations is not statistically significant (95 % confidence level).</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f07.png" target="_blank">Download</a></p></div> <p id="d1e3863">Results in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">6</a> show that the inversion generally pushes the prior EDGAR v4.3.2 estimates of oil and gas emissions toward the UNFCCC values. One would expect the UNFCCC national reports to provide better estimates than EDGAR v4.3.2 because of their use of local information <span class="cit" id="xref_paren.110">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx77" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Scarpelli et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx77" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> as compared to the more generic estimates used by EDGAR on the basis of IPCC Tier 1 methodology <span class="cit" id="xref_paren.111">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx36" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">IPCC</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx36" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2006</a>)</span>. Thus we find that EDGARv4.3.2 greatly underestimates emissions in Uzbekistan, which are high because of leaky infrastructure <span class="cit" id="xref_paren.112">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx77" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Scarpelli et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx77" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span>. For Iran, Algeria, Nigeria, Saudi Arabia, and Qatar we find much<span id="page7869"></span> lower emissions than EDGAR v4.3.2 that are more consistent with the UNFCCC data. For China we are in better agreement with EDGAR v4.3.2 than with the UNFCCC estimate, which relies on anomalously low emission factors <span class="cit" id="xref_paren.113">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx46" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Larsen et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx46" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>. In Venezuela we find higher emissions than both EDGAR v4.3.2 and UNFCCC. The latest available report from Venezuela to the UNFCCC dates back to 1999.</p> </div><div class="sec"><h2 id="Ch1.S3.SS2"><span class="label">3.2</span> Spatial distribution and source attribution of methane emission trends</h2> <p id="d1e3888">Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">7</a> shows base inversion results for the linear emission trends on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M161" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="fd41a72b89412fedd22290deaef712e9"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00050.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00050.png"></image></svg></span></span> grid for 2010–2015 and the associated averaging kernel sensitivities. Also shown in panel d is the 2010–2015 time series of posterior OH concentrations with error standard deviations from the posterior error covariance matrix. We find no significant OH trend over the period, although uncertainties are large. The information on the spatial distribution of emission trends originates from local and regional gradients of atmospheric methane observed by GOSAT, and we find from the posterior error covariance matrix of the inversion that it is not correlated with information on OH concentrations. Thus the large posterior uncertainty in global OH concentrations does not induce any significant correlated error in the spatial distribution of emission trends. This may be expected in view of the long lifetime of methane relative to the relevant timescales for atmospheric transport.</p> <p id="d1e3913">The GOSAT data provide seven independent pieces of information (DOFS) on the spatial distribution of the emission trend. Again, a Bayesian inversion without correcting for overfit (<span class="inline-formula"><i>γ</i>=1</span>) would erroneously indicate much higher DOFS. We find increasing emissions in the tropics and little change at higher latitudes. There are well-defined anthropogenic positive trends over China, India, and the Persian Gulf. Trends in China are in areas with dominant emissions from coal mining but also significant contributions from livestock and waste. In an inversion of surface observations, <span class="cit" id="xref_text.114"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx90" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Thompson et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx90" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> previously found an increasing trend over China for 2000–2011, which they attributed to coal mining. <span class="cit" id="xref_text.115"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span> found that this trend continued up to 2015 using GOSAT in a regional inversion. Trends over India are in areas of rice production but may also reflect waste management and livestock. The trend over India is 0.4 (0.3–0.5) Tg a<span class="inline-formula"><sup>−1</sup></span> (range of the inversion ensemble), consistent with the 2010–2015 trend of <span class="inline-formula">0.7±0.5</span> Tg a<span class="inline-formula"><sup>−1</sup></span> from a regional GOSAT inversion by <span class="cit" id="xref_text.116"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Miller et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2019</a>)</span>. <span class="cit" id="xref_text.117"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx25" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Ganesan et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx25" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span> found a nonsignificant trend (<span class="inline-formula">0.2±0.7</span> Tg a<span class="inline-formula"><sup>−1</sup></span>) over India for 2010–2015 using an ensemble of GOSAT, commercial aircraft (CARIBIC), and surface station<span id="page7870"></span> methane data, but our estimate is not incompatible with their range. EDGAR v4.3.2 predicts a 0.4 Tg a<span class="inline-formula"><sup>−1</sup></span> increase in anthropogenic emissions from India between 2010 and 2012, mainly from livestock, coal, and waste based on increasing activity data (this trend is not included in our prior estimate). The trend over the United States is less well defined and not well constrained but suggests an increase over the eastern part of the country where multiple source types could contribute <span class="cit" id="xref_paren.118">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sheng et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx82" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>)</span>.</p> <p id="d1e4017">Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">7</a>c shows the attribution of the global increasing trend in emissions to individual source types, following the same assumption that was used in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">5</a> to attribute emissions to source types. We further separate tropical and extratropical contributions. Boreal wetland trends cannot be constrained by our inversion effectively (no observations north of 60<span class="inline-formula"><sup>∘</sup></span> N). 43 % of the 5 Tg a<span class="inline-formula"><sup>−1</sup></span> global emission trend found in the inversion for 2010–2015 is driven by wetlands (mainly tropical), 16 % by livestock, and 11 % by oil and gas. No source type shows a global decrease. Our source attribution of the methane trend is consistent with isotopic evidence, suggesting that the increase in methane over the past decade has been driven by biogenic sources outside the Arctic <span class="cit" id="xref_paren.119">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx62" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Nisbet et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx62" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx79" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Schwietzke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx79" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx78" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Schaefer et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx78" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>, including tropical wetlands <span class="cit" id="xref_paren.120">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx51" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">McNorton et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx51" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. <span class="cit" id="xref_text.121"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx106" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Worden et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx106" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span> previously found a decrease in biomass burning from 2001–2007 to 2008–2014 but no significant change for the 2010–2015 period investigated here. Their argument that a decrease in the biomass burning emissions would have masked the effect of an increase in fossil fuel emissions on the isotope signature of methane would not apply for our time period.</p> <span class="tableCitations"></span><div class="table-wrap" id="Ch1.T2"><div class="caption"><p id="d1e4059"><strong class="caption-number">Table 2</strong>Global 2010–2015 methane budget<span class="inline-formula"><sup>a</sup></span>.</p></div><a class="table-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02.png" target="_blank"><img src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02-thumb.png" target="_blank" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02-web.png" data-width="2067" data-height="655" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02.png" data-csvversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02.xlsx"></a><div class="table-wrap-foot"><p id="d1e4071"><span class="inline-formula"><sup>a</sup></span> From the inversion optimizing (1) mean 2010–2015 methane emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M173" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="63bd9f1cf1670c29830bdf3c4c71e2c3"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00053.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00053.png"></image></svg></span></span> grid, (2) linear methane emission trends on that same grid, (3) global mean 2010–2015 tropospheric OH concentration, and (4) linear trend in global OH concentrations. Expected values and error standard deviations are shown. The prior estimates are described in Sect. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.S2.SS2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2.2</a>. The posterior global emission and its trend are obtained by summing the contributions from all <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M174" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="225189efa35d2f890adcfd898e4c6823"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00054.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00054.png"></image></svg></span></span> grid cells, and the error standard deviations are computed accounting for posterior error correlation. Minor methane sinks totaling 61 Tg a<span class="inline-formula"><sup>−1</sup></span> are not optimized in the inversion. <span class="inline-formula"><sup>b</sup></span> Methane lifetime against oxidation by tropospheric OH, computed as the ratio between the total atmospheric mass of methane (including the stratosphere) and the annual loss rate from oxidation by OH in the troposphere.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor table-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02.png" target="_blank">Download Print Version</a><span class="hide-on-mobile download-separator"> | </span><a class="triangle journal-contentLinkColor table-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-t02.xlsx" target="_blank">Download XLSX</a></p></div> </div><div class="sec"><h2 id="Ch1.S3.SS3"><span class="label">3.3</span> Global methane budget and trends</h2> <p id="d1e4373">The previous sections showed that our inversion of the GOSAT data is able to provide relatively fine information on the spatial distribution of methane emissions (DOFS <span class="inline-formula">=</span> 128) as well as some information on the spatial distribution of 2010–2015 emission trends (DOFS <span class="inline-formula">=</span> 7). This information on the spatial distribution originates from local and regional gradients of atmospheric methane observed by GOSAT. We now examine to what extent error correlations may limit our ability to independently quantify the global emission of methane, the global tropospheric OH concentrations, and their respective trends.</p> <div class="fig" id="Ch1.F8"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f08-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f08" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f08-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f08-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f08.png" data-width="2067" data-height="1610"></a><div class="caption"><p id="d1e4392"><strong class="caption-number">Figure 8</strong>Constraints on the global 2010–2015 methane budget from our inversion of GOSAT data. The lines show the rows of the averaging kernel matrix <span class="inline-formula"><strong>A</strong><sub>red</sub></span> (Eq. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">9</a>) for the reduced four-element state vector consisting of the 2010–2015 mean emission, the linear emission trend, the 2010–2015 mean tropospheric OH concentration, and the linear OH trend.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f08.png" target="_blank">Download</a></p></div> <div class="fig" id="Ch1.F9"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f09-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f09" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f09-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f09-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f09.png" data-width="2067" data-height="1006"></a><div class="caption"><p id="d1e4416"><strong class="caption-number">Figure 9</strong>Joint probability density functions (pdfs) for the global methane budget as constrained by the 2010–2015 GOSAT data. Panel <strong>(a)</strong> shows the joint pdfs of the 2010–2015 global mean methane emission and methane lifetime against oxidation by tropospheric OH. Panel <strong>(b)</strong> shows the joint pdfs of the 2010–2015 global emission trend and the OH trend. Contours show confidence ranges from 0.1 to 0.9. The error correlation coefficients are shown inset. The tilt of the ellipse indicates the extent of error correlation.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f09.png" target="_blank">Download</a></p></div> <p id="d1e4432">To analyze the constraints from the inversion on the global budget of methane, we collapse the inversion to the reduced four-member global state vector of 2010–2015 mean values described in Sect. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.S2.SS6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2.6</a> (global methane emission, global emission trend, global tropospheric OH concentration, global OH trend). We use normal errors for all state vector elements (using lognormal errors could bias the mean). Table 2 compares the prior and posterior values for this global budget. The uncertainty in global emissions and trends is likely underestimated because of the lack of prior error covariance assumed between the 1009 grid cells. The global mean tropospheric OH concentration is expressed in terms of the corresponding methane lifetime <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M193" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="italic">τ</mi><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow><mrow class="chem"><mi mathvariant="normal">OH</mi></mrow></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="22pt" height="19pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="b27a753546a1bd696c8cb1d654c63ee7"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00055.svg" width="100%" height="19pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00055.png"></image></svg></span></span>. Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F8" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">8</a> shows the averaging kernel rows for this reduced global state vector (<span class="inline-formula"><strong>A</strong><sub>red</sub></span> in Sect. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.S2.SS6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2.6</a>), measuring the sensitivity of the inversion results to the true values (diagonal terms) and the aliasing due to error correlations (off-diagonal terms). We find that the mean 2010–2015 global methane emission and OH concentration are strongly and independently constrained, with averaging kernel sensitivities near unity and little error correlation. On the other hand, there is strong negative error correlation between emission trends and OH trends, and the OH trend can only be weakly constrained. This is illustrated further in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">9</a> with the joint probability density function (pdf) plots of the<span id="page7871"></span> posterior estimates, where the confidence levels measure the probability of a given value, and the tilts of the ellipses measure the error correlations.</p> <p id="d1e4473">A major implication of being able to constrain the global methane emission and the global OH concentration independently is that satellite observations of atmospheric methane can provide an independent proxy for quantifying the global mean tropospheric OH concentration. Our posterior estimate of the methane lifetime <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M195" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi mathvariant="italic">τ</mi><mrow class="chem"><msub><mi mathvariant="normal">CH</mi><mn mathvariant="normal">4</mn></msub></mrow><mrow class="chem"><mi mathvariant="normal">OH</mi></mrow></msubsup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="22pt" height="19pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="b0e85de9bdeb35276292e8414851252e"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00056.svg" width="100%" height="19pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00056.png"></image></svg></span></span> is <span class="inline-formula">10.8±0.4</span> years. It is strongly constrained by the inversion, as shown by the averaging kernel sensitivity near unity, and is thus largely independent of the prior estimate of <span class="inline-formula">10.6±1.1</span> years. So far the main method for estimating global OH has been through the methyl chloroform budget <span class="cit" id="xref_paren.122">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Prather et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span>, but this is becoming problematic as methyl chloroform concentrations decrease, and previously minor potential sources like ocean outgassing may become significant <span class="cit" id="xref_paren.123">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx100" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wennberg et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx100" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2004</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx48" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Liang et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx48" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>)</span>. Satellite observations of methane could provide an alternative. Our inversion confirms the best estimate of global OH from the methyl chloroform budget <span class="cit" id="xref_paren.124">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Prather et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2012</a>)</span> but reduces its uncertainty from 10 % to 4 %. The magnitude of reduction may be overoptimistic because of the idealized treatment of error statistics, the assumption that the global 3-D OH distribution in the forward model is correct, and the assumption that the minor sinks (Table 1) are correct. <span class="cit" id="xref_text.125"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Zhang et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> present a more thorough error analysis of this potential of methane satellite observations as proxy for global OH concentrations.</p> <p id="d1e4531">We find on the other hand that there is large error correlation between our estimates of global 2010–2015 emission trends and OH trends and limited ability to constrain the OH trend. We find that most of the increase in methane is explained by increasing emissions. Our posterior estimates for the 2010–2015 trends are <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M198" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>+</mo><mn mathvariant="normal">0.84</mn><mo>±</mo><mn mathvariant="normal">0.04</mn></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="64pt" height="10pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="00f16ff2687e0c6608869051cd786c90"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00057.svg" width="100%" height="10pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00057.png"></image></svg></span></span> % a<span class="inline-formula"><sup>−1</sup></span> (<span class="inline-formula">4.6±0.2</span> Tg a<span class="inline-formula"><sup>−1</sup></span>) for emissions and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M202" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">0.2</mn><mo>±</mo><mn mathvariant="normal">0.8</mn></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="28c44cbae44d33f7c88b2029e255bd4a"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00058.svg" width="100%" height="10pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00058.png"></image></svg></span></span> % a<span class="inline-formula"><sup>−1</sup></span> (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M204" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">1.0</mn><mo>±</mo><mn mathvariant="normal">3.8</mn></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="f4772fc239a15bdaa8b6dd30f1658dc5"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00059.svg" width="100%" height="10pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00059.png"></image></svg></span></span> Tg a<span class="inline-formula"><sup>−1</sup></span>) for OH. The joint pdf in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">9</a> illustrates the error correlation between the two. Other factors driving the 2010–2015 atmospheric methane trend are the initial imbalance in the 2010 budget, which we can derive from the posterior estimates of the mean 2010–2015 budget imbalance and trends, and the interannual variability of wetlands emissions as represented by WetCHARTS. Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">10</a> shows the contributions of these different terms to the observed 2010–2015 methane growth. 2010 was a relatively high year for tropical wetlands emissions according to WetCHARTS, which acts to dampen the overall trend. We can state with some confidence that increasing tropical emissions (Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">7</a>) made an important contribution to the 2010–2015 methane trend, but any conclusion about the effect of an OH trend is highly uncertain, including in its sign. Our 2010–2015 growth rate averages 6.8 ppb a<span class="inline-formula"><sup>−1</sup></span>, compared to 7.3 ppb a<span class="inline-formula"><sup>−1</sup></span> in the NOAA record (<span class="uri"><a href="https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/" target="_blank">https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/</a></span>, last access: 27 April 2019). The increase in the NOAA record is higher because of especially strong growth in 2014 (12.8 ppb), which is not fully captured by the linearized optimization used here. In our base inversion, this anomaly is explained by a reduced sink from OH.</p> <div class="fig" id="Ch1.F10"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f10-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f10" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f10-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f10-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f10.png" data-width="2067" data-height="1732"></a><div class="caption"><p id="d1e4673"><strong class="caption-number">Figure 10</strong>Attribution of the 2010–2015 increase in the atmospheric burden of methane. The grey bars show the trend imposed by the 2010 imbalance between sources and sinks combined with the interannual variability (IAV) of the prior estimate (mainly from wetlands). This trend decreases over the 2010–2015 period because the methane sink rises in response to the increasing methane concentration and also because wetland emissions in 2010 are higher than in other years. Purple and orange show the contributions of the 2010–2015 methane emission trends and OH trends. The apportionment of the emission trend by source region and source type is shown in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.F7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">7</a>. The OH trend has high uncertainty as discussed in the text.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f10.png" target="_blank">Download</a></p></div> </div></div><span class="section3-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="sec conclusions" id="section4"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section4 .co-arrow-open,.section4-content" data-show="#section4 .co-arrow-closed,.section4-mobile-bottom-border"><div id="Ch1.S4" class="h1"><span class="label">4</span> Conclusions<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section4-content show-no-js hide-on-mobile-soft"><p id="d1e4693">We used 2010–2015 observations of atmospheric methane columns from the GOSAT satellite instrument in a global inverse analysis to optimize a state vector including (1) mean 2010–2015 methane emissions on a 4<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M208" display="inline" overflow="scroll" dspmath="mathml"><mrow><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="678b5fdb72a50f02f9c44cff9d4f1518"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00060.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00060.png"></image></svg></span></span> grid, (2) 2010–2015 emission trends on that same grid, and (3) global mean tropospheric OH concentrations for individual years. Our work aimed to improve current understanding of global methane sources and the renewed growth in atmospheric<span id="page7872"></span> methane over the past decade and to examine if satellite observations can independently constrain methane emissions and tropospheric OH, the main methane sink.</p><p id="d1e4714">Our inversion used the GEOS-Chem chemical transport model as forward model to relate the state vector elements (1)–(3) to atmospheric methane columns. We fitted the model to the GOSAT observations by analytical solution of the Bayesian problem, including construction of the full Jacobian matrix. The analytical solution provides closed-form characterization of errors and of the information content in the solution. This is critical for diagnosing the ability of the GOSAT observations to constrain emission trends and to achieve separate constraints on emissions and OH concentrations. It also allows us to easily generate an ensemble of inversions testing different assumptions. An analytical solution of the inverse problem generally requires normal prior error distributions, but we show here that it can be readily extended to lognormal prior error distributions by using a simple scaling of the original Jacobian matrix.</p><p id="d1e4717">Our optimization of mean 2010–2015 methane emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M209" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="e69487382bc5299e9fa8a179f3b32020"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00061.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00061.png"></image></svg></span></span> grid achieves 128 degrees of information for signal (DOFS), with strong constraints in source regions. The EDGAR v4.3.2 anthropogenic emission inventory taken as default anthropogenic prior estimate in the inversion is too high in China (coal emissions) and in the Middle East (oil and gas emissions). Oil and gas national totals in EDGAR v4.3.2 can differ greatly from the values reported by individual countries to the United Nations Framework Convention on Climate Change (UNFCCC), and our inversion results are generally more consistent with the UNFCCC estimates. We find little correction to anthropogenic US emissions when a new gridded version of the US EPA greenhouse gas inventory is used as the anthropogenic prior estimate. Previous inverse studies that relied on the EDGAR v4.2 inventory as prior estimate found large underestimates of US emissions, but this may reflect errors in the spatial distribution of EDGAR v4.2 oil and gas emissions.</p><p id="d1e4740">Optimization of methane emission trends over the 2010–2015 period yields DOFS of 7 on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M210" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="4d9b1de69bbf72369d77b84727a49daf"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00062.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00062.png"></image></svg></span></span> grid, meaning that only strong source regions can be constrained. We find that the 2010–2015 increasing trend in atmospheric methane is mostly due to increasing emissions rather than decreasing OH concentrations. Most of the increase is in tropical wetlands, India, and China. Trends in North America and Europe are small. Our findings are consistent with isotopic constraints pointing to tropical biogenic sources as responsible for the renewed growth of methane over the past decade.</p><p id="d1e4764">We further examined the ability of the GOSAT data to constrain the global methane emission and its trend over the 2010–2015 period independently of the global OH concentration and its trend. For this purpose we considered a reduced four-component state vector consisting of (1) the global mean methane emission for 2010–2015, (2) the global emission trend over that period, (3) the global mean OH concentration for 2010–2015, and (4) the global OH trend over that period. (1) and (2) were obtained by collapsing the inverse solutions for emissions on the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M211" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="c21105c32f2419a40679197e9163c67e"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00063.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00063.png"></image></svg></span></span> grid, so that the distributions of emissions and their trends are still optimized. Results show that the global methane emission (<span class="inline-formula">546±2</span> Tg a<span class="inline-formula"><sup>−1</sup></span>) can be constrained independently of the global OH concentration (atmospheric methane lifetime against oxidation by tropospheric OH of <span class="inline-formula">10.8±0.4</span> years), with little error correlation. This is because methane emissions and loss have different and separable signatures on atmospheric methane columns. An important implication is that satellite observations of atmospheric methane can serve as a useful proxy for the global OH concentration. In contrast, we find that errors on the 2010–2015 OH trends are strongly correlated with the stronger signal from emission trends.</p><p id="d1e4823">Satellite observations of atmospheric methane are expected to vastly improve in the near future with the launch of the TROPOMI instrument in October 2017, the advent of geostationary observations from the GeoCARB instrument to be launched in the early 2020s, and other instruments measuring methane on local to global scales <span class="cit" id="xref_paren.126">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx39" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Jacob et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx39" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a>)</span>. Our work with the relatively sparse GOSAT data suggests that this future constellation of satellites will enable the mapping of emissions at fine scales. Satellite observations of methane could also provide an effective means for<span id="page7873"></span> monitoring OH concentrations, replacing methyl chloroform whose ability to serve as an OH proxy is declining.</p></div><span class="section4-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div id="section5" class="sec"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section5 .co-arrow-open,.section5-content" data-show="#section5 .co-arrow-closed,.section5-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Data availability<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section5-content show-no-js hide-on-mobile-soft"><p id="d1e4834">TCCON data were obtained from the TCCON data archive, hosted by CaltechDATA – <span class="uri"><a href="https://tccondata.org/" target="_blank">https://tccondata.org/</a></span> (last access: 27 April 2019) <span class="cit" id="xref_paren.127">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx87" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Strong et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx87" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2017</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx108" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wunch et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx108" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx57" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Morino et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx57" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx57" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx58" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx101" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Wennberg et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx101" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx101" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx102" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx103" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx103" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx104" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx37" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Iraci et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx37" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2016</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx37" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx38" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx43" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kivi et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx43" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Blumenstock et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx15" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">De Mazière et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx15" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Dubey et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx19" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx89" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Te et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx89" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx41" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Kawakami et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx41" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx29" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Hase et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx29" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx26" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Griffith et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx26" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx26" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx27" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx83" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sherlock et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx83" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx88" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Sussmann and Rettinger</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx88" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx16" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Deutscher et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx16" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx63" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Notholt et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx63" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>; <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Warneke et al.</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2014</a>)</span>.</p></div><span class="section5-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="app sec" id="section6"> <div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section6 .co-arrow-open,.section6-content" data-show="#section6 .co-arrow-closed,.section6-mobile-bottom-border"><div id="App1.Ch1.S1" class="h1"><span>Appendix A:</span> Comparison of forward model simulations at 4<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 5<span class="inline-formula"><sup>∘</sup></span> and 2<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 2.5<span class="inline-formula"><sup>∘</sup></span> resolutions<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section6-content show-no-js hide-on-mobile-soft"><p id="d1e4906"><span class="cit" id="xref_text.128"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Stanevich</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2018</a>)</span> pointed out significant global meridional biases in the GEOS-Chem simulation of methane columns at <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M221" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="8d6e1a544801223c1f03b8b2be42db74"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00064.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00064.png"></image></svg></span></span> resolution relative to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M222" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">2</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">2.5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="43pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="e44755e6bd79341e842eb309f9ee27e5"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00065.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00065.png"></image></svg></span></span>, and they argued that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M223" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">2</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">2.5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="43pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="6ee3b35ca0d1936f93c3514ac6e088c4"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00066.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00066.png"></image></svg></span></span> was much better for use in global inversions of methane sources. However, we find that most of the difference between the two resolutions is in the stratosphere, which we correct following Eq. (<a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.E1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">1</a>). Figure <a href="https://acp.copernicus.org/articles/19/7859/2019/#App1.Ch1.S1.F11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">A1</a> illustrates this point with the differences between the two resolutions averaged over latitudinal bands. Values are 2010–2015 means for the full column and for the tropospheric column only. There are large high-latitude biases for the total column, but these are mainly in the stratosphere. The tropospheric bias is less than 5 ppb at all latitudes. Results for individual seasons are similar. <span class="cit" id="xref_text.129"><a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Buchwitz et al.</a> (<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span> consider that biases below 10 ppb are acceptable in methane inversions.</p><div class="fig" id="App1.Ch1.S1.F11"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f11-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f11" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f11-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f11-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f11.png" data-width="2067" data-height="1512"></a><div class="caption"><p id="d1e4981"><strong class="caption-number">Figure A1</strong>Difference between methane column concentrations simulated by GEOS-Chem at <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M224" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">4</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="34bff08b03908905ef79931479604ba2"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00067.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00067.png"></image></svg></span></span> versus <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M225" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">2</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">2.5</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="43pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="1a1bab6e568f706a14f784c1b65be9ab"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00068.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00068.png"></image></svg></span></span>. Values are 2010–2015 averages over latitudinal bands for total atmospheric columns and tropospheric columns.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f11.png" target="_blank">Download</a></p></div></div><span class="section6-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="app sec" id="section7"> <div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section7 .co-arrow-open,.section7-content" data-show="#section7 .co-arrow-closed,.section7-mobile-bottom-border"><div id="App1.Ch1.S2" class="h1"><span>Appendix B:</span> Sensitivity to seasonal bias in prior emission estimates<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section7-content show-no-js hide-on-mobile-soft"><p id="d1e5042">The GEOS-Chem forward model simulation using prior emission estimates shows a seasonal background bias relative to GOSAT observations, for which we applied a latitude-dependent correction (Sect. <a href="https://acp.copernicus.org/articles/19/7859/2019/#Ch1.S2.SS3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2.3</a>). This correction could mask a bias in the seasonality of prior emissions. We conducted an additional inversion in which we did not apply this seasonal correction and instead optimized emissions for individual seasons with no prior error correlation between seasons. This brings the total size of the state vector up to 5052, which challenges the power of the GOSAT observations to provide independent constraints. As shown in Fig. <a href="https://acp.copernicus.org/articles/19/7859/2019/#App1.Ch1.S2.F12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">B1</a>, the effective posterior / prior ratios found by summing the seasonal emissions are very similar to the ones from the base inversion. This indicates that the global pattern of scaling factors is not driven by corrections made to improve the seasonal agreement between the model and GOSAT. The effective scaling factors are smaller in magnitude and smoother than the previous results because fewer observations are available per state vector element, resulting in smoothing error <span class="cit" id="xref_paren.130">(<a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx92" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Turner and Jacob</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#bib1.bibx92" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">2015</a>)</span>.</p><div class="fig" id="App1.Ch1.S2.F12"><a target="_blank" class="figure-link" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f12-web.png"><img alt="https://www.atmos-chem-phys.net/19/7859/2019/acp-19-7859-2019-f12" data-webversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f12-web.png" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f12-thumb.png" data-printversion="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f12.jpg" data-width="2067" data-height="1579"></a><div class="caption"><p id="d1e5054"><strong class="caption-number">Figure B1</strong>Results from the seasonal inversion, showing effective posterior / prior scaling factors in the top panel and the seasonal scaling factors in the four bottom panels.</p></div><p class="downloads"><a class="triangle journal-contentLinkColor figure-download" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-f12.jpg" target="_blank">Download</a></p></div></div><span class="section7-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div id="section8" class="sec"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section8 .co-arrow-open,.section8-content" data-show="#section8 .co-arrow-closed,.section8-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Author contributions<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section8-content show-no-js hide-on-mobile-soft"><p id="d1e5071">JDM and DJJ designed the study. JDM performed the analysis. JDM, MPS, HN, and MH performed simulations and supporting simulations and analysis. JDM, DJJ, MPS, TRS, HN, JXS, YZ, MH, AAB, KWB, and JRW discussed the results. AAB provided the WetCHARTS emissions and supporting data. GJM provided guidance and supporting data on the EDGAR v4.3.2 emissions. RJP provided the GOSAT data and supporting guidance. JDM and DJJ wrote the paper, and all authors provided input on the paper for revision before submission.</p></div><span class="section8-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div id="section9" class="sec"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section9 .co-arrow-open,.section9-content" data-show="#section9 .co-arrow-closed,.section9-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Competing interests<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section9-content show-no-js hide-on-mobile-soft"><p id="d1e5077">The authors declare that they have no conflict of interest.</p></div><span class="section9-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="ack sec" id="section10"> <div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section10 .co-arrow-open,.section10-content" data-show="#section10 .co-arrow-closed,.section10-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Acknowledgements<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section10-content show-no-js hide-on-mobile-soft"><p id="d1e5083">We thank the anonymous reviewers and Luke Western for their thorough comments. Robert J.Parker thanks the Japanese Aerospace Exploration Agency, National Institute for Environmental Studies, and the Ministry of Environment for the GOSAT data and their continuous support as part of the Joint Research Agreement. This research used the ALICE High Performance Computing Facility at the University of Leicester for the GOSAT retrievals.</p></div><span class="section10-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div id="section11" class="sec"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section11 .co-arrow-open,.section11-content" data-show="#section11 .co-arrow-closed,.section11-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Financial support<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section11-content show-no-js hide-on-mobile-soft"><p id="d1e5088">This research was funded by the Carbon Monitoring System program of the NASA Earth Science Division. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Kevin W. Bowman acknowledges support from the NASA Carbon Monitoring System (NNH16ZDA001N-CMS). Robert J. Parker is funded by the UK National Centre for Earth Observation (NCEO grant no. nceo020005) and the ESA Greenhouse Gas Climate Change Initiative (GHG-CCI).</p></div><span class="section11-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div id="section12" class="sec"><div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section12 .co-arrow-open,.section12-content" data-show="#section12 .co-arrow-closed,.section12-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>Review statement<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section12-content show-no-js hide-on-mobile-soft"><p id="d1e5094">This paper was edited by Andreas Hofzumahaus and reviewed by two anonymous referees.</p></div><span class="section12-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> <div class="ref-list sec" id="section13"> <div class="grid-container no-margin header-element"><span class="grid-100 mobile-grid-100 tablet-grid-100 grid-parent more-less-mobile" data-hide="#section13 .co-arrow-open,.section13-content" data-show="#section13 .co-arrow-closed,.section13-mobile-bottom-border"><div class="h1"><span class="section-number"> </span>References<span class="hide-on-desktop hide-on-tablet triangleWrapper"> <i class="co-arrow-closed"></i><i class="co-arrow-open" style="display:none"></i></span></div></span></div> <div class="section13-content show-no-js hide-on-mobile-soft"><p class="ref" id="bib1.bibx1"><span class="mixed-citation">Alexe, M., Bergamaschi, P., Segers, A., Detmers, R., Butz, A., Hasekamp, O., Guerlet, S., Parker, R., Boesch, H., Frankenberg, C., Scheepmaker, R. A., Dlugokencky, E., Sweeney, C., Wofsy, S. C., and Kort, E. A.: Inverse modelling of CH4 emissions for 2010–2011 using different satellite retrieval products from GOSAT and SCIAMACHY, Atmos. Chem. Phys., 15, 113–133, <a href="https://doi.org/10.5194/acp-15-113-2015">https://doi.org/10.5194/acp-15-113-2015</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx2"><span class="mixed-citation">Allan, W., Struthers, H., and Lowe, D.: Methane carbon isotope effects caused by atomic chlorine in the marine boundary layer: Global model results compared with Southern Hemisphere measurements, J. Geophys. Res.-Atmos., 112, D04306, <a href="https://doi.org/10.1029/2006JD007369">https://doi.org/10.1029/2006JD007369</a>, 2007. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.63" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx3"><span class="mixed-citation">Alvarez, R. A., Zavala-Araiza, D., Lyon, D. R., Allen, D. T., Barkley, Z. R., Brandt, A. R., Davis, K. J., Herndon, S. C., Jacob, D. J., Karion, A., Kort, E. A., Lamb, B. K., Lauvaux, T., Maasakkers, J. D., Marchese, A. J., Omara, M., Pacala, S. W., Peischl, J., Robinson, A. L., Shepson, P. B., Sweeney, C., Townsend-Small, A., Wofsy, S. C., and Hamburg, S. P.: Assessment of methane emissions from the U.S. oil and gas supply chain, Science, 361, 186–188, <a href="https://doi.org/10.1126/science.aar7204">https://doi.org/10.1126/science.aar7204</a>, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.108" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx4"><span class="mixed-citation">Bader, W., Bovy, B., Conway, S., Strong, K., Smale, D., Turner, A. J., Blumenstock, T., Boone, C., Collaud Coen, M., Coulon, A., Garcia, O., Griffith, D. W. T., Hase, F., Hausmann, P., Jones, N., Krummel, P., Murata, I., Morino, I., Nakajima, H., O'Doherty, S., Paton-Walsh, C., Robinson, J., Sandrin, R., Schneider, M., Servais, C., Sussmann, R., and Mahieu, E.: The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005, Atmos. Chem. Phys., 17, 2255–2277, <a href="https://doi.org/10.5194/acp-17-2255-2017">https://doi.org/10.5194/acp-17-2255-2017</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx5"><span class="mixed-citation">Bergamaschi, P., Frankenberg, C., Meirink, J. F., Krol, M., Dentener, F., Wagner, T., Platt, U., Kaplan, J. O., Körner, S., Heimann, M., Dlugokencky, E. J., and Goede, A.: Satellite chartography of atmospheric methane from SCIAMACHY on board ENVISAT: 2. Evaluation based on inverse model simulations, J. Geophys. Res.-Atmos., 112, D02304, <a href="https://doi.org/10.1029/2006JD007268">https://doi.org/10.1029/2006JD007268</a>, 2007. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.71" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx6"><span class="mixed-citation">Bloom, A. A., Bowman, K. W., Lee, M., Turner, A. J., Schroeder, R., Worden, J. R., Weidner, R., McDonald, K. C., and Jacob, D. J.: A global wetland methane emissions and uncertainty dataset for atmospheric chemical transport models (WetCHARTs version 1.0), Geosci. Model Dev., 10, 2141–2156, <a href="https://doi.org/10.5194/gmd-10-2141-2017">https://doi.org/10.5194/gmd-10-2141-2017</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.28" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.44" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.48" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.104" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a></span></p><p class="ref" id="bib1.bibx7"><span class="mixed-citation">Blumenstock, T., Hase, F., Schneider, M., Garcia, O. E., andv67 Sepulveda, E.: TCCON data from Izana (ES), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.izana01.R0/114929">https://doi.org/10.14291/tccon.ggg2014.izana01.R0/114929</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx8"><span class="mixed-citation">Bosilovich, M. G., Lucchesi, R., and Suarez, M.: File Specification for MERRA-2. GMAO Office Note No. 9 (Version 1.1), 73 pp., available at: <span class="uri"><a href="https://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf" target="_blank">https://gmao.gsfc.nasa.gov/pubs/docs/Bosilovich785.pdf</a></span> (last access: 27 April 2019), 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.58" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx9"><span class="mixed-citation">Brasseur, G. and Jacob, D.: Mathematical Modeling of Atmospheric Chemistry, Cambridge University Press, <a href="https://doi.org/10.1017/9781316544754">https://doi.org/10.1017/9781316544754</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.85" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx10"><span class="mixed-citation">Buchwitz, M., Reuter, M., Schneising, O., Boesch, H., Guerlet, S., Dils, B., Aben, I., Armante, R., Bergamaschi, P., Blumenstock, T., Bovensmann, H., Brunner, D., Buchmann, B., Burrows, J. P., Butz, A., Chédin, A., Chevallier, F., Crevoisier, C. D., Deutscher, N. M., Frankenberg, C., Hase, F., Hasekamp, O. P., Heymann, J., Kaminski, T., Laeng, A., Lichtenberg, G., De Mazière, M., Noël, S., Notholt, J., Orphal, J., Popp, C., Parker, R., Scholze, M., Sussmann, R., Stiller, G. P., Warneke, T., Zehner, C., Bril, A., Crisp, D., Griffith, D. W. T., Kuze, A., O'Dell, C., Oshchepkov, S., Sherlock, V., Suto, H., Wennberg, P., Wunch, D., Yokota, T., and Yoshida, Y.: Comparison and quality assessment of near-surface-sensitive satellite-derived <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">CH<sub>4</sub></span> global data sets, Remote Sens. Environ., 162, 344–362, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.17" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.24" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.25" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.129" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a></span></p><p class="ref" id="bib1.bibx11"><span class="mixed-citation">Butz, A., Guerlet, S., Hasekamp, O., Schepers, D., Galli, A., Aben, I., Frankenberg, C., Hartmann, J.-M., Tran, H., and Kuze, A.: Toward accurate <span class="inline-formula">CO<sub>2</sub></span> and <span class="inline-formula">CH<sub>4</sub></span> observations from GOSAT, Geophys. Res. Lett., 38, L14812, <a href="https://doi.org/10.1029/2011GL047888">https://doi.org/10.1029/2011GL047888</a>, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.17" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.21" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><span id="page7877"></span><p class="ref" id="bib1.bibx12"><span class="mixed-citation">Calisesi, Y., Soebijanta, V. T., and van Oss Roeland: Regridding of remote soundings: Formulation and application to ozone profile comparison, J. Geophys. Res.-Atmos., 110, D23306, <a href="https://doi.org/10.1029/2005JD006122">https://doi.org/10.1029/2005JD006122</a>, 2005. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.95" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx13"><span class="mixed-citation">Cressot, C., Chevallier, F., Bousquet, P., Crevoisier, C., Dlugokencky, E. J., Fortems-Cheiney, A., Frankenberg, C., Parker, R., Pison, I., Scheepmaker, R. A., Montzka, S. A., Krummel, P. B., Steele, L. P., and Langenfelds, R. L.: On the consistency between global and regional methane emissions inferred from SCIAMACHY, TANSO-FTS, IASI and surface measurements, Atmos. Chem. Phys., 14, 577–592, <a href="https://doi.org/10.5194/acp-14-577-2014">https://doi.org/10.5194/acp-14-577-2014</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx14"><span class="mixed-citation"> Darmenov, A. and da Silva, A.: The quick fire emissions dataset (QFED)–documentation of versions 2.1, 2.2 and 2.4, NASA Technical Report Series on Global Modeling and Data Assimilation, NASA TM-2013-104606, 32, 183 pp., 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.34" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx15"><span class="mixed-citation">De Mazière, M., Sha, M. K., Desmet, F., Hermans, C., Scolas, F., Kumps, N., Metzger, J.-M., Duflot, V., and Cammas, J.-P.: TCCON data from Reunion Island (RE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.reunion01.R0/1149288">https://doi.org/10.14291/tccon.ggg2014.reunion01.R0/1149288</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx16"><span class="mixed-citation">Deutscher, N. M., Notholt, J., Messerschmidt, J., Weinzierl, C., Warneke, T., Petri, C., Grupe, P., and Katrynski, K.: TCCON data from Bialystok (PL), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.bialystok01.R1/1183984">https://doi.org/10.14291/tccon.ggg2014.bialystok01.R1/1183984</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx17"><span class="mixed-citation"> Dlugokencky, E. J., Nisbet, E. G., Fisher, R., and Lowry, D.: Global atmospheric methane: budget, changes and dangers, Philos. T. R. Soc. S.-A, 369, 2058–2072, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx18"><span class="mixed-citation">Dubey, M., Henderson, B., Green, D., Butterfield, Z., Keppel-Aleks, G., Allen, N., Blavier, J.-F., Roehl, C., Wunch, D., and Lindenmaier, R.: TCCON data from Manaus (BR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.manaus01.R0/1149274">https://doi.org/10.14291/tccon.ggg2014.manaus01.R0/1149274</a>, 2014a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx19"><span class="mixed-citation">Dubey, M., Lindenmaier, R., Henderson, B., Green, D., Allen, N., Roehl, C., Blavier, J.-F., Butterfield, Z., Love, S., Hamelmann, J., and Wunch, D.: TCCON data from Four Corners (US), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.fourcorners01.R0/1149272">https://doi.org/10.14291/tccon.ggg2014.fourcorners01.R0/1149272</a>, 2014b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx20"><span class="mixed-citation">EIA: Shapefile for sedimentary basin boundaries in Lower 48 States, available at: <span class="uri"><a href="http://eia.gov/maps/map_data/SedimentaryBasins_US_EIA.zip" target="_blank">http://eia.gov/maps/map_data/SedimentaryBasins_US_EIA.zip</a></span> (last access: 27 April 2019), 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.40" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx21"><span class="mixed-citation"> Etiope, G.: Natural Gas Seepage: The Earth's Hydrocarbon Degassing, Springer, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.36" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx22"><span class="mixed-citation"> Etiope, G. and Klusman, R. W.: Microseepage in drylands: flux and implications in the global atmospheric source/sink budget of methane, Global Planet. Change, 72, 265–274, 2010. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.41" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx23"><span class="mixed-citation">Franco, B., Mahieu, E., Emmons, L. K., Tzompa-Sosa, Z. A., Fischer, E. V., Sudo, K., Bovy, B., Conway, S., Griffin, D., Hannigan, J. W., Strong, K., and Walker, K. A.: Evaluating ethane and methane emissions associated with the development of oil and natural gas extraction in North America, Environ. Res. Lett., 11, 044010, <a href="https://doi.org/10.1088/1748-9326/11/4/044010">https://doi.org/10.1088/1748-9326/11/4/044010</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx24"><span class="mixed-citation"> Fung, I., John, J., Lerner, J., Matthews, E., Prather, M., Steele, L., and Fraser, P.: Three-dimensional model synthesis of the global methane cycle, J. Geophys. Res.-Atmos., 96, 13033–13065, 1991. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.35" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.64" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx25"><span class="mixed-citation">Ganesan, A. L., Rigby, M., Lunt, M. F., Parker, R. J., Boesch, H., Goulding, N., Umezawa, T., Zahn, A., Chatterjee, A., Prinn, R. G., Tiwari, Y. K., van der Schoot, M., and Krummel, P. B.: Atmospheric observations show accurate reporting and little growth in India's methane emissions, Nature Commun., 8, 836, <a href="https://doi.org/10.1038/s41467-017-00994-7">https://doi.org/10.1038/s41467-017-00994-7</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.117" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx26"><span class="mixed-citation">Griffith, D. W., Deutscher, N. M., Velazco, V. A., Wennberg, P. O., Yavin, Y., Aleks, G. K., Washenfelder, R. a., Toon, G. C., Blavier, J.-F., Murphy, C., Jones, N., Kettlewell, G., Connor, B. J., Macatangay, R., Roehl, C., Ryczek, M., Glowacki, J., Culgan, T., and Bryant, G.: TCCON data from Darwin (AU), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.darwin01.R0/1149290">https://doi.org/10.14291/tccon.ggg2014.darwin01.R0/1149290</a>, 2014a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx27"><span class="mixed-citation">Griffith, D. W., Velazco, V. A., Deutscher, N. M., Murphy, C., Jones, N., Wilson, S., Macatangay, R., Kettlewell, G., Buchholz, R. R., and Riggenbach, M.: TCCON data from Wollongong (AU), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.wollongong01.R0/1149291">https://doi.org/10.14291/tccon.ggg2014.wollongong01.R0/1149291</a>, 2014b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx28"><span class="mixed-citation"> Hartmann, D. L., Tank, A. M. K., Rusticucci, M., Alexander, L. V., Brönnimann, S., Charabi, Y. A. R., Dentener, F. J., Dlugokencky, E. J., Easterling, D. R., Kaplan, A., Soden, B. J., Thorne, P. W., Wild, M., and Zhai, P. M.: Observations: atmosphere and surface, in: Climate Change 2013 the Physical Science Basis: Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx29"><span class="mixed-citation">Hase, F., Blumenstock, T., Dohe, S., Gross, J., and Kiel, M.: TCCON data from Karlsruhe (DE), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.karlsruhe01.R1/1182416">https://doi.org/10.14291/tccon.ggg2014.karlsruhe01.R1/1182416</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx30"><span class="mixed-citation">Hausmann, P., Sussmann, R., and Smale, D.: Contribution of oil and natural gas production to renewed increase in atmospheric methane (2007–2014): top–down estimate from ethane and methane column observations, Atmos. Chem. Phys., 16, 3227–3244, <a href="https://doi.org/10.5194/acp-16-3227-2016">https://doi.org/10.5194/acp-16-3227-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx31"><span class="mixed-citation">Heald, C. L., Jacob, D. J., Jones, D., Palmer, P. I., Logan, J. A., Streets, D., Sachse, G. W., Gille, J. C., Hoffman, R. N., and Nehrkorn, T.: Comparative inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide, J. Geophys. Res.-Atmos., 109, D23306, <a href="https://doi.org/10.1029/2004JD005185">https://doi.org/10.1029/2004JD005185</a>, 2004. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.77" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx32"><span class="mixed-citation">Holmes, C. D., Prather, M. J., Søvde, O. A., and Myhre, G.: Future methane, hydroxyl, and their uncertainties: key climate and emission parameters for future predictions, Atmos. Chem. Phys., 13, 285–302, <a href="https://doi.org/10.5194/acp-13-285-2013">https://doi.org/10.5194/acp-13-285-2013</a>, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.8" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.54" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx33"><span class="mixed-citation">Holmquist, J. R., Windham-Myers, L., Bliss, N., Crooks, S., Morris, J. T., Megonigal, J. P., Troxler, T., Weller, D., Callaway, J., Drexler, J., Ferner, M. C., Gonneea, M. E., Kroeger, K. D., Schile-Beers, L., Woo, I., Buffington, K., Breithaupt, J., Boyd, B. M., Brown, L. N., Dix, N., Hice, L., Horton, B. P., MacDonald, G. M., Moyer, R. P., Reay, W., Shaw, T., Smith, E., Smoak,<span id="page7878"></span> J. M., Sommerfield, C., Thorne, K., Velinsky, D., Watson, E., Wilson Grimes, K., and Woodrey, M.: Accuracy and Precision of Tidal Wetland Soil Carbon Mapping in the Conterminous United States, Sci. Rep., 8, 9478, <a href="https://doi.org/10.1038/s41598-018-26948-7">https://doi.org/10.1038/s41598-018-26948-7</a>, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.103" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx34"><span class="mixed-citation">Hossaini, R., Chipperfield, M. P., Saiz-Lopez, A., Fernandez, R., Monks, S., Feng, W., Brauer, P., and von Glasow, R.: A global model of tropospheric chlorine chemistry: Organic versus inorganic sources and impact on methane oxidation, J. Geophys. Res.-Atmos., 121, 14271–14297, <a href="https://doi.org/10.1002/2016JD025756">https://doi.org/10.1002/2016JD025756</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.66" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx35"><span class="mixed-citation">Houweling, S., Bergamaschi, P., Chevallier, F., Heimann, M., Kaminski, T., Krol, M., Michalak, A. M., and Patra, P.: Global inverse modeling of <span class="inline-formula">CH<sub>4</sub></span> sources and sinks: an overview of methods, Atmos. Chem. Phys., 17, 235–256, <a href="https://doi.org/10.5194/acp-17-235-2017">https://doi.org/10.5194/acp-17-235-2017</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.89" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx36"><span class="mixed-citation"> IPCC: Guidelines for National Greenhouse Gas Inventories, in: The National Greenhouse Gas Inventories Programme, edited by: Eggleston, H. S., Buendia, L., Miwa, K., Ngara, T., and Tanabe, K., Hayama, Kanagawa, Japan, 2006. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.111" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx37"><span class="mixed-citation">Iraci, L. T., Podolske, J., Hillyard, P. W., Roehl, C., Wennberg, P. O., Blavier, J.-F., Allen, N., Wunch, D., Osterman, G. B., and Albertson, R.: TCCON data from Edwards (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.edwards01.R1/1255068">https://doi.org/10.14291/tccon.ggg2014.edwards01.R1/1255068</a>, 2016a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx38"><span class="mixed-citation">Iraci, L. T., Podolske, J., Hillyard, P. W., Roehl, C., Wennberg, P. O., Blavier, J.-F., Landeros, J., Allen, N., Wunch, D., Zavaleta, J., Quigley, E., Osterman, G. B., Barrow, E., and Barney, J.: TCCON data from Indianapolis (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.indianapolis01.R1/1330094">https://doi.org/10.14291/tccon.ggg2014.indianapolis01.R1/1330094</a>, 2016b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx39"><span class="mixed-citation">Jacob, D. J., Turner, A. J., Maasakkers, J. D., Sheng, J., Sun, K., Liu, X., Chance, K., Aben, I., McKeever, J., and Frankenberg, C.: Satellite observations of atmospheric methane and their value for quantifying methane emissions, Atmos. Chem. Phys., 16, 14371–14396, <a href="https://doi.org/10.5194/acp-16-14371-2016">https://doi.org/10.5194/acp-16-14371-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.126" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx40"><span class="mixed-citation">Janssens-Maenhout, G., Crippa, M., Guizzardi, D., Muntean, M., Schaaf, E., Dentener, F., Bergamaschi, P., Pagliari, V., Olivier, J., Peters, J., van Aardenne, J., Monni, S., Doering, U., Petrescu, R., Solazzo, E., and Oreggioni, G.: EDGAR v4.3.2 Global Atlas of the three major Greenhouse Gas Emissions for the period 1970–2012, Earth Syst. Sci. Data Discuss., <a href="https://doi.org/10.5194/essd-2018-164">https://doi.org/10.5194/essd-2018-164</a>, in review, 2019. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.29" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.101" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx41"><span class="mixed-citation">Kawakami, S., Ohyama, H., Arai, K., Okumura, H., Taura, C., Fukamachi, T., and Sakashita, M.: TCCON data from Saga (JP), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.saga01.R0/1149283">https://doi.org/10.14291/tccon.ggg2014.saga01.R0/1149283</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx42"><span class="mixed-citation"> Kirschke, S., Bousquet, P., Ciais, P., Saunois, M., Canadell, J. G., Dlugokencky, E. J., Bergamaschi, P., Bergmann, D., Blake, D. R., and Bruhwiler, L.: Three decades of global methane sources and sinks, Nat. Geosci., 6, 813–823, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.42" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a></span></p><p class="ref" id="bib1.bibx43"><span class="mixed-citation">Kivi, R., Heikkinen, P., and Kyrö, E.: TCCON data from Sodankyla (FI), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.sodankyla01.R0/1149280">https://doi.org/10.14291/tccon.ggg2014.sodankyla01.R0/1149280</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx44"><span class="mixed-citation">Kuze, A., Suto, H., Shiomi, K., Kawakami, S., Tanaka, M., Ueda, Y., Deguchi, A., Yoshida, J., Yamamoto, Y., Kataoka, F., Taylor, T. E., and Buijs, H. L.: Update on GOSAT TANSO-FTS performance, operations, and data products after more than 6 years in space, Atmos. Meas. Tech., 9, 2445–2461, <a href="https://doi.org/10.5194/amt-9-2445-2016">https://doi.org/10.5194/amt-9-2445-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.17" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.22" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx45"><span class="mixed-citation"> Kvenvolden, K. A. and Rogers, B. W.: Gaia's breath-global methane exhalations, Mar. Petrol. Geol., 22, 579–590, 2005. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.37" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.38" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx46"><span class="mixed-citation"> Larsen, K., Delgado, M., and Marsters, P.: Untapped potential: Reducing global methane emissions from oil and natural gas systems, Rhodium Group, LLC, New York, NY, USA, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.113" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx47"><span class="mixed-citation"> Lehner, B. and Döll, P.: Development and validation of a global database of lakes, reservoirs and wetlands, J. Hydrol., 296, 1–22, 2004. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.104" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx48"><span class="mixed-citation">Liang, Q., Chipperfield, M. P., Fleming, E. L., Abraham, N. L., Braesicke, P., Burkholder, J. B., Daniel, J. S., Dhomse, S., Fraser, P. J., Hardiman, S. C., Jackman, C. H., Kinnison, D. E., Krummel, P. B., Montzka, S. A., Morgenstern, O., McCulloch, A., Mühle, J., Newman, P. A., Orkin, V. L., Pitari, G., Prinn, R. G., Rigby, M., Rozanov, E., Stenke, A., Tummon, F., Velders, G. J. M., Visioni, D., and Weiss, R. F.: Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CH3CCl3 Alternatives, J. Geophys. Res.-Atmos., 122, 11914–11933, <a href="https://doi.org/10.1002/2017JD026926">https://doi.org/10.1002/2017JD026926</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.123" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx49"><span class="mixed-citation"> Lyon, D. R., Zavala-Araiza, D., Alvarez, R. A., Harriss, R., Palacios, V., Lan, X., Talbot, R., Lavoie, T., Shepson, P., and Yacovitch, T. I.: Constructing a spatially resolved methane emission inventory for the Barnett Shale region, Environ. Sci. Technol., 49, 8147–8157, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.39" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx50"><span class="mixed-citation"> Maasakkers, J. D., Jacob, D. J., Sulprizio, M. P., Turner, A. J., Weitz, M., Wirth, T., Hight, C., DeFigueiredo, M., Desai, M., and Schmeltz, R.: Gridded national inventory of US methane emissions, Environ. Sci. Technol., 50, 13123–13133, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.30" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.32" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.45" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.47" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.106" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">e</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.107" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">f</a></span></p><p class="ref" id="bib1.bibx51"><span class="mixed-citation">McNorton, J., Gloor, E., Wilson, C., Hayman, G. D., Gedney, N., Comyn-Platt, E., Marthews, T., Parker, R. J., Boesch, H., and Chipperfield, M. P.: Role of regional wetland emissions in atmospheric methane variability, Geophys. Res. Lett., 43, 11433–11444, <a href="https://doi.org/10.1002/2016GL070649">https://doi.org/10.1002/2016GL070649</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.120" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx52"><span class="mixed-citation">McNorton, J., Wilson, C., Gloor, M., Parker, R. J., Boesch, H., Feng, W., Hossaini, R., and Chipperfield, M. P.: Attribution of recent increases in atmospheric methane through 3-D inverse modelling, Atmos. Chem. Phys., 18, 18149–18168, <a href="https://doi.org/10.5194/acp-18-18149-2018">https://doi.org/10.5194/acp-18-18149-2018</a>, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.14" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx53"><span class="mixed-citation">Miller, S. M., Wofsy, S. C., Michalak, A. M., Kort, E. A., Andrews, A. E., Biraud, S. C., Dlugokencky, E. J., Eluszkiewicz, J., Fischer, M. L., Janssens-Maenhout, G., Miller, B. R., Miller, J. B., Montzka, S. A., Nehrkorn, T., and Sweeney, C.: Anthropogenic emissions of methane in the United States, P. Natl. Acad. Sci. USA, 110, 20018–20022, <a href="https://doi.org/10.1073/pnas.1314392110">https://doi.org/10.1073/pnas.1314392110</a>, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.105" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx54"><span class="mixed-citation">Miller, S. M., Michalak, A. M., and Levi, P. J.: Atmospheric inverse modeling with known physical bounds: an example from trace gas emissions, Geosci. Model Dev., 7, 303–315, <a href="https://doi.org/10.5194/gmd-7-303-2014">https://doi.org/10.5194/gmd-7-303-2014</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.83" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.92" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx55"><span class="mixed-citation">Miller, S. M., Michalak, A. M., Detmers, R. G., Hasekamp, O. P., Bruhwiler, L. M., and Schwietzke, S.: China's coal mine methane<span id="page7879"></span> regulations have not curbed growing emissions, Nat. Commun., 10, 303, <a href="https://doi.org/10.1038/s41467-018-07891-7">https://doi.org/10.1038/s41467-018-07891-7</a>, 2019. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.99" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.115" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.116" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a></span></p><p class="ref" id="bib1.bibx56"><span class="mixed-citation">Monteil, G., Houweling, S., Butz, A., Guerlet, S., Schepers, D., Hasekamp, O., Frankenberg, C., Scheepmaker, R., Aben, I., and Röckmann, T.: Comparison of <span class="inline-formula">CH<sub>4</sub></span> inversions based on 15 months of GOSAT and SCIAMACHY observations, J. Geophys. Res.-Atmos., 118, 11807–11823, <a href="https://doi.org/10.1002/2013JD019760">https://doi.org/10.1002/2013JD019760</a>, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx57"><span class="mixed-citation">Morino, I., Matsuzaki, T., and Shishime, A.: TCCON data from Tsukuba (JP), 125HR, Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.tsukuba02.R1/1241486">https://doi.org/10.14291/tccon.ggg2014.tsukuba02.R1/1241486</a>, 2014a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx58"><span class="mixed-citation">Morino, I., Yokozeki, N., Matzuzaki, T., and Horikawa, M.: TCCON data from Rikubetsu (JP), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.rikubetsu01.R1/1242265">https://doi.org/10.14291/tccon.ggg2014.rikubetsu01.R1/1242265</a>, 2014b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx59"><span class="mixed-citation">Murray, L. T., Jacob, D. J., Logan, J. A., Hudman, R. C., and Koshak, W. J.: Optimized regional and interannual variability of lightning in a global chemical transport model constrained by LIS/OTD satellite data, J. Geophys. Res.-Atmos., 117, D20307, <a href="https://doi.org/10.1029/2012JD017934">https://doi.org/10.1029/2012JD017934</a>, 2012. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.61" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx60"><span class="mixed-citation">Naik, V., Voulgarakis, A., Fiore, A. M., Horowitz, L. W., Lamarque, J.-F., Lin, M., Prather, M. J., Young, P. J., Bergmann, D., Cameron-Smith, P. J., Cionni, I., Collins, W. J., Dalsøren, S. B., Doherty, R., Eyring, V., Faluvegi, G., Folberth, G. A., Josse, B., Lee, Y. H., MacKenzie, I. A., Nagashima, T., van Noije, T. P. C., Plummer, D. A., Righi, M., Rumbold, S. T., Skeie, R., Shindell, D. T., Stevenson, D. S., Strode, S., Sudo, K., Szopa, S., and Zeng, G.: Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Atmos. Chem. Phys., 13, 5277–5298, <a href="https://doi.org/10.5194/acp-13-5277-2013">https://doi.org/10.5194/acp-13-5277-2013</a>, 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.52" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.56" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx61"><span class="mixed-citation">Naus, S., Montzka, S. A., Pandey, S., Basu, S., Dlugokencky, E. J., and Krol, M.: Constraints and biases in a tropospheric two-box model of OH, Atmos. Chem. Phys., 19, 407–424, <a href="https://doi.org/10.5194/acp-19-407-2019">https://doi.org/10.5194/acp-19-407-2019</a>, 2019. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.16" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx62"><span class="mixed-citation"> Nisbet, E., Dlugokencky, E., Manning, M., Lowry, D., Fisher, R., France, J., Michel, S., Miller, J., White, J., Vaughn, B., Bousquet, P., Pyle, J. A., Warwick, N. J., Cain, M., Brownlow, R., Zazzeri, G., Lanoisellé, M., Manning, A. C., Gloor, E., Worthy, D. E. J., Brunke, E.-G., Labuschagne, C., Wolff, E. W., and Ganesan, A. L.: Rising atmospheric methane: 2007–2014 growth and isotopic shift, Global Biogeochem. Cy., 30, 1356–1370, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.119" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx63"><span class="mixed-citation">Notholt, J., Petri, C., Warneke, T., Deutscher, N. M., Buschmann, M., Weinzierl, C., Macatangay, R., and Grupe, P.: TCCON data from Bremen (DE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.bremen01.R0/1149275">https://doi.org/10.14291/tccon.ggg2014.bremen01.R0/1149275</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx64"><span class="mixed-citation">Pandey, S., Houweling, S., Krol, M., Aben, I., Chevallier, F., Dlugokencky, E. J., Gatti, L. V., Gloor, E., Miller, J. B., Detmers, R., Machida, T., and Röckmann, T.: Inverse modeling of GOSAT-retrieved ratios of total column <span class="inline-formula">CH<sub>4</sub></span> and <span class="inline-formula">CO<sub>2</sub></span> for 2009 and 2010, Atmos. Chem. Phys., 16, 5043–5062, <a href="https://doi.org/10.5194/acp-16-5043-2016">https://doi.org/10.5194/acp-16-5043-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx65"><span class="mixed-citation">Pandey, S., Houweling, S., Krol, M., Aben, I., Monteil, G., Nechita-Banda, N., Dlugokencky, E. J., Detmers, R., Hasekamp, O., Xu, X., Riley, W. J., Poulter, B., Zhang, Z., McDonald, K. C., White, J. W. C., Bousquet, P., and Röckmann, T.: Enhanced methane emissions from tropical wetlands during the 2011 La Niña, Sci. Rep., 7, 45759, <a href="https://doi.org/10.1038/srep45759">https://doi.org/10.1038/srep45759</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx66"><span class="mixed-citation">Parker, R., Boesch, H., Cogan, A., Fraser, A., Feng, L., Palmer, P. I., Messerschmidt, J., Deutscher, N., Griffith, D. W., and Notholt, J.: Methane observations from the Greenhouse Gases Observing SATellite: Comparison to ground-based TCCON data and model calculations, Geophys. Res. Lett., 38, L15807, <a href="https://doi.org/10.1029/2011GL047871">https://doi.org/10.1029/2011GL047871</a>, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.23" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx67"><span class="mixed-citation">Parker, R. J., Boesch, H., Byckling, K., Webb, A. J., Palmer, P. I., Feng, L., Bergamaschi, P., Chevallier, F., Notholt, J., Deutscher, N., Warneke, T., Hase, F., Sussmann, R., Kawakami, S., Kivi, R., Griffith, D. W. T., and Velazco, V.: Assessing 5 years of GOSAT Proxy XCH<span class="inline-formula"><sub>4</sub></span> data and associated uncertainties, Atmos. Meas. Tech., 8, 4785–4801, <a href="https://doi.org/10.5194/amt-8-4785-2015">https://doi.org/10.5194/amt-8-4785-2015</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.23" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.27" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.74" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.80" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a></span></p><p class="ref" id="bib1.bibx68"><span class="mixed-citation">Patra, P. K., Houweling, S., Krol, M., Bousquet, P., Belikov, D., Bergmann, D., Bian, H., Cameron-Smith, P., Chipperfield, M. P., Corbin, K., Fortems-Cheiney, A., Fraser, A., Gloor, E., Hess, P., Ito, A., Kawa, S. R., Law, R. M., Loh, Z., Maksyutov, S., Meng, L., Palmer, P. I., Prinn, R. G., Rigby, M., Saito, R., and Wilson, C.: TransCom model simulations of CH<span class="inline-formula"><sub>4</sub></span> and related species: linking transport, surface flux and chemical loss with CH<span class="inline-formula"><sub>4</sub></span> variability in the troposphere and lower stratosphere, Atmos. Chem. Phys., 11, 12813–12837, <a href="https://doi.org/10.5194/acp-11-12813-2011">https://doi.org/10.5194/acp-11-12813-2011</a>, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.70" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx69"><span class="mixed-citation">Peng, S., Piao, S., Bousquet, P., Ciais, P., Li, B., Lin, X., Tao, S., Wang, Z., Zhang, Y., and Zhou, F.: Inventory of anthropogenic methane emissions in mainland China from 1980 to 2010, Atmos. Chem. Phys., 16, 14545-14562, <a href="https://doi.org/10.5194/acp-16-14545-2016">https://doi.org/10.5194/acp-16-14545-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.100" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx70"><span class="mixed-citation"> Petrenko, V. V., Smith, A. M., Schaefer, H., Riedel, K., Brook, E., Baggenstos, D., Harth, C., Hua, Q., Buizert, C., Schilt, A., Fain, X., Mitchell, L., Bauska, T., Orsi, A., Weiss, R. F., and Severinghaus, J. P.: Minimal geological methane emissions during the Younger Dryas–Preboreal abrupt warming event, Nature, 548, 443–446, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.43" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx71"><span class="mixed-citation">Prather, M. J., Holmes, C. D., and Hsu, J.: Reactive greenhouse gas scenarios: Systematic exploration of uncertainties and the role of atmospheric chemistry, Geophys. Res. Lett., 39, L09803, <a href="https://doi.org/10.1029/2012GL051440">https://doi.org/10.1029/2012GL051440</a>, 2012. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.51" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.53" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.122" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.124" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">e</a></span></p><p class="ref" id="bib1.bibx72"><span class="mixed-citation"> Ridgwell, A. J., Marshall, S. J., and Gregson, K.: Consumption of atmospheric methane by soils: A process-based model, Global Biogeochem. Cy., 13, 59–70, 1999. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.65" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx73"><span class="mixed-citation"> Rigby, M., Montzka, S. A., Prinn, R. G., White, J. W., Young, D., O'Doherty, S., Lunt, M. F., Ganesan, A. L., Manning, A. J., Simmonds, P. G., Salameh, P. K., Harth, C. M., Mühle, J., Weiss, R. F., Fraser, P. J., Steele, L. P., Krummel, P. B., McCulloch, A., and Park, S.: Role of atmospheric oxidation in recent methane growth, P. Natl. Acad. Sci. USA, 114, 5373–5377, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.14" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx74"><span class="mixed-citation"> Rodgers, C. D.: Inverse methods for atmospheric sounding: theory and practice, Series on Atmospheric Oceanic and Planetary Physics, vol. 2, World scientific, 256 pp., 2000. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.20" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.81" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.84" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.91" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.93" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">e</a></span></p><p class="ref" id="bib1.bibx75"><span class="mixed-citation">Saad, K. M., Wunch, D., Deutscher, N. M., Griffith, D. W. T., Hase, F., De Mazière, M., Notholt, J., Pollard, D. F., Roehl, C. M., Schneider, M., Sussmann, R., Warneke, T., and Wennberg,<span id="page7880"></span> P. O.: Seasonal variability of stratospheric methane: implications for constraining tropospheric methane budgets using total column observations, Atmos. Chem. Phys., 16, 14003–14024, <a href="https://doi.org/10.5194/acp-16-14003-2016">https://doi.org/10.5194/acp-16-14003-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.69" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx76"><span class="mixed-citation">Saunois, M., Bousquet, P., Poulter, B., Peregon, A., Ciais, P., Canadell, J. G., Dlugokencky, E. J., Etiope, G., Bastviken, D., Houweling, S., Janssens-Maenhout, G., Tubiello, F. N., Castaldi, S., Jackson, R. B., Alexe, M., Arora, V. K., Beerling, D. J., Bergamaschi, P., Blake, D. R., Brailsford, G., Brovkin, V., Bruhwiler, L., Crevoisier, C., Crill, P., Covey, K., Curry, C., Frankenberg, C., Gedney, N., Höglund-Isaksson, L., Ishizawa, M., Ito, A., Joos, F., Kim, H.-S., Kleinen, T., Krummel, P., Lamarque, J.-F., Langenfelds, R., Locatelli, R., Machida, T., Maksyutov, S., McDonald, K. C., Marshall, J., Melton, J. R., Morino, I., Naik, V., O'Doherty, S., Parmentier, F.-J. W., Patra, P. K., Peng, C., Peng, S., Peters, G. P., Pison, I., Prigent, C., Prinn, R., Ramonet, M., Riley, W. J., Saito, M., Santini, M., Schroeder, R., Simpson, I. J., Spahni, R., Steele, P., Takizawa, A., Thornton, B. F., Tian, H., Tohjima, Y., Viovy, N., Voulgarakis, A., van Weele, M., van der Werf, G. R., Weiss, R., Wiedinmyer, C., Wilton, D. J., Wiltshire, A., Worthy, D., Wunch, D., Xu, X., Yoshida, Y., Zhang, B., Zhang, Z., and Zhu, Q.: The global methane budget 2000–2012, Earth Syst. Sci. Data, 8, 697–751, <a href="https://doi.org/10.5194/essd-8-697-2016">https://doi.org/10.5194/essd-8-697-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx77"><span class="mixed-citation"> Scarpelli, T., Jacob, D., Maasakkers, J. D., Sheng, J.-X., Rose, K., Sulprizio, M. P., and Worden, J.: A Global Gridded Inventory of Methane Emissions from Fuel Exploitation including Oil, Gas, and Coal, AGU 2018 Fall Meeting Abstract, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.110" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.112" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx78"><span class="mixed-citation">Schaefer, H., Fletcher, S. E. M., Veidt, C., Lassey, K. R., Brailsford, G. W., Bromley, T. M., Dlugokencky, E. J., Michel, S. E., Miller, J. B., Levin, I., Lowe, D. C., Martin, R. J., Vaughn, B. H., and White, J. W. C.: A 21st-century shift from fossil-fuel to biogenic methane emissions indicated by <span class="inline-formula"><sup>13</sup></span>CH<span class="inline-formula"><sub>4</sub></span>, Science, 352, 80–84, <a href="https://doi.org/10.1126/science.aad2705">https://doi.org/10.1126/science.aad2705</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.119" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx79"><span class="mixed-citation"> Schwietzke, S., Sherwood, O. A., Bruhwiler, L. M., Miller, J. B., Etiope, G., Dlugokencky, E. J., Michel, S. E., Arling, V. A., Vaughn, B. H., White, J. W., and Tans, P. P.: Upward revision of global fossil fuel methane emissions based on isotope database, Nature, 538, 88–91, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.119" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx80"><span class="mixed-citation">Sheng, J.-X., Jacob, D. J., Maasakkers, J. D., Sulprizio, M. P., Zavala-Araiza, D., and Hamburg, S. P.: A high-resolution (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M239" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.1</mn><msup><mi></mi><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">0.1</mn><msup><mi></mi><mo>∘</mo></msup></mrow></math><span><svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="11pt" class="hide-js svg-formula" dspmath="mathimg" md5hash="e3a96cdb6e848036b40cd82f5c4e445c"><image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00069.svg" width="100%" height="11pt" src="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019-ie00069.png"></image></svg></span></span>) inventory of methane emissions from Canadian and Mexican oil and gas systems, Atmos. Environ., 158, 211–215, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.31" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx81"><span class="mixed-citation">Sheng, J.-X., Jacob, D. J., Turner, A. J., Maasakkers, J. D., Benmergui, J., Bloom, A. A., Arndt, C., Gautam, R., Zavala-Araiza, D., Boesch, H., and Parker, R. J.: 2010–2016 methane trends over Canada, the United States, and Mexico observed by the GOSAT satellite: contributions from different source sectors, Atmos. Chem. Phys., 18, 12257–12267, <a href="https://doi.org/10.5194/acp-18-12257-2018">https://doi.org/10.5194/acp-18-12257-2018</a>, 2018a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.49" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.118" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx82"><span class="mixed-citation">Sheng, J.-X., Jacob, D. J., Turner, A. J., Maasakkers, J. D., Sulprizio, M. P., Bloom, A. A., Andrews, A. E., and Wunch, D.: High-resolution inversion of methane emissions in the Southeast US using SEAC4RS aircraft observations of atmospheric methane: anthropogenic and wetland sources, Atmos. Chem. Phys., 18, 6483–6491, <a href="https://doi.org/10.5194/acp-18-6483-2018">https://doi.org/10.5194/acp-18-6483-2018</a>, 2018b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.102" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.118" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx83"><span class="mixed-citation">Sherlock, V., Connor, B. J., Robinson, J., Shiona, H., Smale, D., and Pollard, D.: TCCON data from Lauder (NZ), 120HR, Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.lauder01.R0/1149293">https://doi.org/10.14291/tccon.ggg2014.lauder01.R0/1149293</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx84"><span class="mixed-citation">Sherwen, T., Schmidt, J. A., Evans, M. J., Carpenter, L. J., Großmann, K., Eastham, S. D., Jacob, D. J., Dix, B., Koenig, T. K., Sinreich, R., Ortega, I., Volkamer, R., Saiz-Lopez, A., Prados-Roman, C., Mahajan, A. S., and Ordóñez, C.: Global impacts of tropospheric halogens (Cl, Br, I) on oxidants and composition in GEOS-Chem, Atmos. Chem. Phys., 16, 12239–12271, <a href="https://doi.org/10.5194/acp-16-12239-2016">https://doi.org/10.5194/acp-16-12239-2016</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.62" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx85"><span class="mixed-citation"> Stanevich, I.: Variational data assimilation of satellite remote sensing observations for improving methane simulations in chemical transport models, PhD thesis, University of Toronto, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.72" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.76" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.128" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a></span></p><p class="ref" id="bib1.bibx86"><span class="mixed-citation"> Stocker, T. F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S. K., Boschung, J., Nauels, A., Xia, Y., Bex, V., and Midgley, P. M.: Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, 1535 pp., 2013. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx87"><span class="mixed-citation">Strong, K., Mendonca, J., Weaver, D., Fogal, P., Drummond, J., Batchelor, R., and Lindenmaier, R.: TCCON data from Eureka (CA), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.eureka01.R1/1325515">https://doi.org/10.14291/tccon.ggg2014.eureka01.R1/1325515</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx88"><span class="mixed-citation">Sussmann, R. and Rettinger, M.: TCCON data from Garmisch (DE), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.garmisch01.R0/1149299">https://doi.org/10.14291/tccon.ggg2014.garmisch01.R0/1149299</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx89"><span class="mixed-citation">Te, Y., Jeseck, P., and Janssen, C.: TCCON data from Paris (FR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.paris01.R0/1149279">https://doi.org/10.14291/tccon.ggg2014.paris01.R0/1149279</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx90"><span class="mixed-citation">Thompson, R. L., Stohl, A., Zhou, L. X., Dlugokencky, E., Fukuyama, Y., Tohjima, Y., Kim, S.-Y., Lee, H., Nisbet, E. G., Fisher, R. E., Lowry, D., Weiss, R. F., Prinn, R. G., O'Doherty, S., Young, D., and White, J. W. C.: Methane emissions in East Asia for 2000–2011 estimated using an atmospheric Bayesian inversion, J. Geophys. Res.-Atmos., 120, 4352–4369, <a href="https://doi.org/10.1002/2014JD022394">https://doi.org/10.1002/2014JD022394</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.114" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx91"><span class="mixed-citation">Thompson, R. L., Nisbet, E. G., Pisso, I., Stohl, A., Blake, D., Dlugokencky, E. J., Helmig, D., and White, J. W. C.: Variability in Atmospheric Methane From Fossil Fuel and Microbial Sources Over the Last Three Decades, Geophys. Res. Lett., 45, 11499–11508, <a href="https://doi.org/10.1029/2018GL078127">https://doi.org/10.1029/2018GL078127</a>, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx92"><span class="mixed-citation">Turner, A. J. and Jacob, D. J.: Balancing aggregation and smoothing errors in inverse models, Atmos. Chem. Phys., 15, 7039–7048, <a href="https://doi.org/10.5194/acp-15-7039-2015">https://doi.org/10.5194/acp-15-7039-2015</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.130" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx93"><span class="mixed-citation">Turner, A. J., Jacob, D. J., Wecht, K. J., Maasakkers, J. D., Lundgren, E., Andrews, A. E., Biraud, S. C., Boesch, H., Bowman, K. W., Deutscher, N. M., Dubey, M. K., Griffith, D. W. T., Hase, F., Kuze, A., Notholt, J., Ohyama, H., Parker, R., Payne, V. H., Sussmann, R., Sweeney, C., Velazco, V. A., Warneke, T., Wennberg, P. O., and Wunch, D.: Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data, Atmos. Chem. Phys., 15, 7049–7069, <a href="https://doi.org/10.5194/acp-15-7049-2015">https://doi.org/10.5194/acp-15-7049-2015</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.18" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.26" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.46" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.57" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.59" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">e</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.68" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">f</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.73" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">g</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.75" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">h</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.79" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">i</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.90" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">j</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.98" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">k</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.105" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">l</a></span></p><span id="page7881"></span><p class="ref" id="bib1.bibx94"><span class="mixed-citation">Turner, A. J., Jacob, D. J., Benmergui, J., Wofsy, S. C., Maasakkers, J. D., Butz, A., Hasekamp, O., and Biraud, S. C.: A large increase in U.S. methane emissions over the past decade inferred from satellite data and surface observations, Geophys. Res. Lett., 43, 2218–2224, <a href="https://doi.org/10.1002/2016GL067987">https://doi.org/10.1002/2016GL067987</a>, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.49" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx95"><span class="mixed-citation"> Turner, A. J., Frankenberg, C., Wennberg, P. O., and Jacob, D. J.: Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl, P. Natl. Acad. Sci. USA, 114, 5367–5372, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.14" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.15" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a></span></p><p class="ref" id="bib1.bibx96"><span class="mixed-citation">UNFCCC: United Nations Framework Convention on Climate Change: Greenhouse Gas Inventory Data, available at: <span class="uri"><a href="https://unfccc.int/process/transparency-and-reporting/greenhouse-gas-data/ghg-data-unfccc" target="_blank">https://unfccc.int/process/transparency-and-reporting/greenhouse-gas-data/ghg-data-unfccc</a></span> (last access: 27 April 2019), 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.109" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx97"><span class="mixed-citation">Wang, X., Jacob, D. J., Eastham, S. D., Sulprizio, M. P., Zhu, L., Chen, Q., Alexander, B., Sherwen, T., Evans, M. J., Lee, B. H., Haskins, J. D., Lopez-Hilfiker, F. D., Thornton, J. A., Huey, G. L., and Liao, H.: The role of chlorine in global tropospheric chemistry, Atmos. Chem. Phys., 19, 3981–4003, <a href="https://doi.org/10.5194/acp-19-3981-2019">https://doi.org/10.5194/acp-19-3981-2019</a>, 2019. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.67" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx98"><span class="mixed-citation">Warneke, T., Messerschmidt, J., Notholt, J., Weinzierl, C., Deutscher, N. M., Petri, C., Grupe, P., Vuillemin, C., Truong, F., Schmidt, M., Ramonet, M., and Parmentier, E.: TCCON data from Orléans (FR), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.orleans01.R0/1149276">https://doi.org/10.14291/tccon.ggg2014.orleans01.R0/1149276</a>, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx99"><span class="mixed-citation"> Wecht, K. J., Jacob, D. J., Frankenberg, C., Jiang, Z., and Blake, D. R.: Mapping of North American methane emissions with high spatial resolution by inversion of SCIAMACHY satellite data, J. Geophys. Res.-Atmos., 119, 7741–7756, 2014. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.50" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.57" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.60" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.78" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a></span></p><p class="ref" id="bib1.bibx100"><span class="mixed-citation">Wennberg, P. O., Peacock, S., Randerson, J. T., and Bleck, R.: Recent changes in the air-sea gas exchange of methyl chloroform, Geophys. Res. Lett., 31, L16112, <a href="https://doi.org/10.1029/2004GL020476">https://doi.org/10.1029/2004GL020476</a>, 2004. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.123" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx101"><span class="mixed-citation">Wennberg, P. O., Roehl, C., Wunch, D., Toon, G. C., Blavier, J.-F., Washenfelder, R. a., Keppel-Aleks, G., Allen, N., and Ayers, J.: TCCON data from Park Falls (US), Release GGG2014R0, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.parkfalls01.R0/1149161">https://doi.org/10.14291/tccon.ggg2014.parkfalls01.R0/1149161</a>, 2014a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx102"><span class="mixed-citation">Wennberg, P. O., Wunch, D., Roehl, C., Blavier, J.-F., Toon, G. C., and Allen, N.: TCCON data from Caltech (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.pasadena01.R1/1182415">https://doi.org/10.14291/tccon.ggg2014.pasadena01.R1/1182415</a>, 2014b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx103"><span class="mixed-citation">Wennberg, P. O., Roehl, C., Blavier, J.-F., Wunch, D., Landeros, J., and Allen, N.: TCCON data from Jet Propulsion Laboratory (US), 2011, Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.jpl02.R1/1330096">https://doi.org/10.14291/tccon.ggg2014.jpl02.R1/1330096</a>, 2016a. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx104"><span class="mixed-citation">Wennberg, P. O., Wunch, D., Roehl, C., Blavier, J.-F., Toon, G. C., Allen, N., Dowell, P., Teske, K., Martin, C., and Martin, J.: TCCON data from Lamont (US), Release GGG2014R1, TCCON data archive, hosted by CaltechDATA, <a href="https://doi.org/10.14291/tccon.ggg2014.lamont01.R1/1255070">https://doi.org/10.14291/tccon.ggg2014.lamont01.R1/1255070</a>, 2016b. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx105"><span class="mixed-citation"> Wofsy, S. C.: HIAPER Pole-to-Pole Observations (HIPPO): fine-grained, global-scale measurements of climatically important atmospheric gases and aerosols, Philos. T. R. Soc. S.-A, 369, 2073–2086, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.96" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx106"><span class="mixed-citation">Worden, J. R., Bloom, A. A., Pandey, S., Jiang, Z., Worden, H. M., Walker, T. W., Houweling, S., and Röckmann, T.: Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget, Nat. Commun., 8, 2227, <a href="https://doi.org/10.1038/s41467-017-02246-0">https://doi.org/10.1038/s41467-017-02246-0</a>, 2017. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.13" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.121" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx107"><span class="mixed-citation"> Wunch, D., Toon, G. C., Blavier, J.-F. L., Washenfelder, R. A., Notholt, J., Connor, B. J., Griffith, D. W., Sherlock, V., and Wennberg, P. O.: The total carbon column observing network, Philos. T. R. Soc. S.-A, 369, 2087–2112, 2011. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_altparen.97" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx108"><span class="mixed-citation">Wunch, D., Toon, G. C., Sherlock, V., Deutscher, N. M., Liu, C., Feist, D. G., and Wennberg, P. O.: The Total Carbon Column Observing Network's GGG2014 Data Version, Tech. rep., California Institute of Technology, Pasadena, CA, <a href="https://doi.org/10.14291/tccon.ggg2014.documentation.R0/1221662">https://doi.org/10.14291/tccon.ggg2014.documentation.R0/1221662</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.127" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx109"><span class="mixed-citation">Zavala-Araiza, D., Lyon, D. R., Alvarez, R. A., Davis, K. J., Harriss, R., Herndon, S. C., Karion, A., Kort, E. A., Lamb, B. K., Lan, X., Marchese, A. J., Pacala, S. W., Robinson, A. L., Shepson, P. B., Sweeney, C., Talbot, R., Townsend-Small, A., Yacovitch, T. I., Zimmerle, D. J., and Hamburg, S. P.: Reconciling divergent estimates of oil and gas methane emissions, P. Natl. Acad. Sci. USA, 112, 15597–15602, <a href="https://doi.org/10.1073/pnas.1522126112">https://doi.org/10.1073/pnas.1522126112</a>, 2015. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.82" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.108" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a></span></p><p class="ref" id="bib1.bibx110"><span class="mixed-citation"> Zhang, B., Tian, H., Ren, W., Tao, B., Lu, C., Yang, J., Banger, K., and Pan, S.: Methane emissions from global rice fields: Magnitude, spatiotemporal patterns, and environmental controls, Global Biogeochem. Cy., 30, 1246–1263, 2016. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.33" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a></span></p><p class="ref" id="bib1.bibx111"><span class="mixed-citation">Zhang, Y., Jacob, D. J., Maasakkers, J. D., Sulprizio, M. P., Sheng, J.-X., Gautam, R., and Worden, J.: Monitoring global tropospheric OH concentrations using satellite observations of atmospheric methane, Atmos. Chem. Phys., 18, 15959–15973, <a href="https://doi.org/10.5194/acp-18-15959-2018">https://doi.org/10.5194/acp-18-15959-2018</a>, 2018. <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.19" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">a</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.55" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">b</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.86" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">c</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.87" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">d</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.88" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">e</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_paren.94" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">f</a>, <a href="https://acp.copernicus.org/articles/19/7859/2019/#xref_text.125" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">g</a></span></p></div><span class="section13-mobile-bottom-border mobile-bottom-border hide-on-desktop hide-on-tablet"></span></div> </div>  <div class="pswp" tabindex="-1" role="dialog" aria-hidden="true" >  <div class="pswp__bg"></div>  <div class="pswp__scroll-wrap">  <div class="pswp__container"> <div class="pswp__item"></div> <div class="pswp__item"></div> <div class="pswp__item"></div> </div>  <div class="pswp__ui pswp__ui--hidden"> <div class="pswp__top-bar">  <div class="pswp__counter"></div> <button class="pswp__button pswp__button--close" title="Close (Esc)"></button> <button class="pswp__button pswp__button--fs" title="Toggle fullscreen"></button>   <div class="pswp__preloader"> <div class="pswp__preloader__icn"> <div class="pswp__preloader__cut"> <div class="pswp__preloader__donut"></div> </div> </div> </div> </div> <div class="pswp__share-modal pswp__share-modal--hidden pswp__single-tap"> <div class="pswp__share-tooltip"></div> </div> <button class="pswp__button pswp__button--arrow--left" title="Previous (arrow left)"> </button> <button class="pswp__button pswp__button--arrow--right" title="Next (arrow right)"> </button> <div class="pswp__caption "> <div class="pswp__caption__center"></div> </div> </div> </div> </div></div>  <div id="page_colum_left_container" class="CMSCONTAINER w-sidebar col-auto d-none d-lg-block"> <div class="auto-fixed-top no-shadow old-articleNavigation"> <div id="quicklaunch_buttons" class="cmsbox jo_quicklaunch-bar"> <a href="https://acp.copernicus.org/" class="article-button journal-contentLinkColor journal-contentBorderColor">Articles </a> </div> <div id="main-navigation" class="cmsbox j-navigation"> <ul class="co_function_get_navigation menu_level1"> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#abstract" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Abstract</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section1" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Introduction</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section2" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Data and methods</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section3" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Results and discussion</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section4" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Conclusions</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section5" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Data availability</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section6" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title"><span>Appendix A:</span> Comparison of forward model simulations at 4<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 5<span class="inline-formula"><sup>∘</sup></span> and 2<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 2.5<span class="inline-formula"><sup>∘</sup></span> resolutions</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section7" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title"><span>Appendix B:</span> Sensitivity to seasonal bias in prior emission estimates</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section8" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Author contributions</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section9" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Competing interests</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section10" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Acknowledgements</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section11" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Financial support</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section12" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Review statement</a></li> <li class="menuitem_level1 co_function_get_navigation_is_parent co_function_get_navigation_is_closed" id="co_getnavigation_page_about"> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section13" class="link_level1 scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">References</a></li> </ul> </div> </div> <div id="leftColumnExtras" class="CMSCONTAINER w-sidebar col-auto d-none d-lg-block pt-2"> <div class="widget dark-border"> <div class="legend journal-contentLinkColor">Download</div> <div class="content"> <ul class="additional_info no-bullets no-styling"> <li><a class="triangle" title="PDF Version (7890 KB)" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.pdf">Article</a> <nobr>(7890 KB)</nobr> </li> <li> <a class="triangle" title="XML Version" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.xml">Full-text XML</a> </li> </ul> </div> <div class="content"> <ul class="additional_info no-bullets no-styling"> <li><a class="triangle" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.bib">BibTeX</a></li> <li><a class="triangle" href="https://acp.copernicus.org/articles/19/7859/2019/acp-19-7859-2019.ris">EndNote</a></li> </ul> </div> </div> <div class="widget dark-border"> <div class="legend journal-contentLinkColor">Short summary</div> <div class="content hide-js shortSummaryFull">We use 2010–2015 satellite observations of atmospheric methane to improve estimates of methane emissions and their trends, as well as the concentration and trend of tropospheric OH (hydroxyl radical, methane's main sink). We find overestimates of Chinese coal and Middle East oil/gas emissions in the prior estimate. The 2010–2015 growth in methane is attributed to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH is small in comparison.</div> <div style="display: none" class="content show-js shortSummaryShorten">We use 2010–2015 satellite observations of atmospheric methane to improve estimates of methane...</div> <div class="content"> <a href="#" class="more-less show-js triangle" data-hide=".shortSummaryFull" data-show=".shortSummaryShorten" data-toggleCaption='Hide'>Read more</a> </div> </div> <div class="widget dark-border hide-on-mobile hide-on-tablet p-0" id="share"> <div class="legend journal-contentLinkColor">Share</div> <div class="row p-0"> <div class="col-auto pl-0"> <a class="share-one-line" href="https://www.mendeley.com/import/?url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Mendeley" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/mendeley.png" alt="Mendeley"/> </a> </div> <div class="col-auto"> <a class="share-one-line" href="https://www.reddit.com/submit?url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Reddit" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/reddit.png" alt="Reddit"> </a> </div> <div class="col-auto"> <a class="share-one-line last" href="https://twitter.com/intent/tweet?text=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015 https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F" title="Twitter" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/twitter.png" alt="Twitter"/> </a> </div> <div class="col-auto"> <a class="share-one-line" href="https://www.facebook.com/share.php?u=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F&t=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015" title="Facebook" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/facebook.png" alt="Facebook"/> </a> </div> <div class="col-auto pr-0"> <a class="share-one-line last" href="https://www.linkedin.com/shareArticle?mini=true&url=https%3A%2F%2Facp.copernicus.org%2Farticles%2F19%2F7859%2F2019%2F&title=Global+distribution+of+methane+emissions%2C+emission+trends%2C+and+OH+concentrations+and+trends+inferred+from+an+inversion+of+GOSAT+satellite+data+for+2010%E2%80%932015" title="LinkedIn" target="_blank"> <img src="https://www.atmospheric-chemistry-and-physics.net/linkedin.png" alt="LinkedIn"> </a> </div> <div class="col pr-0 mobile-native-share"> <a href="#" data-title="Atmospheric Chemistry and Physics" data-text="*Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015* Joannes D. Maasakkers et al." data-url="https://acp.copernicus.org/articles/19/7859/2019/" class="mobile-native-share share-one-line last"><i class="co-mobile-share display-none"></i></a> </div> </div> </div> <div class="widget dark-border"> <div class="legend journal-contentLinkColor">Altmetrics</div> <div class="wrapper"> <div class="content text-center"> Final-revised paper </div> <div class="content text-center"> <div class="altmetric-embed" data-link-target="_blank" data-hide-less-than="1" data-no-score data-badge-type="medium-donut" data-doi="10.5194/acp-19-7859-2019"></div> </div> </div> <div class="wrapper"> <div class="content text-center"> Preprint </div> <div class="content text-center"> <div class="altmetric-embed" data-link-target="_blank" data-hide-less-than="1" data-no-score data-badge-type="medium-donut" data-doi="10.5194/acp-2018-1365"></div> </div> </div> </div> <script type="text/javascript"> !function (e, t, n) { var d = "createElement", c = "getElementsByTagName", m = "setAttribute", n = document.getElementById(e); return n && n.parentNode && n.parentNode.removeChild(n), n = document[d + "NS"] && document.documentElement.namespaceURI, n = n ? document[d + "NS"](n, "script") : document[d]("script"), n[m]("id", e), n[m]("src", t), (document[c]("head")[0] || document[c]("body")[0]).appendChild(n), n = new Image, void n[m]("src", "https://www.atmospheric-chemistry-and-physics.net/altmetric_donut.png") }("altmetric-embed-js", "https://www.atmospheric-chemistry-and-physics.net/altmetric_badges.min.js"); $(function () { $('div.altmetric-embed').on('altmetric:hide', function () { if($(this).closest('.widget').find('.altmetric-embed:not(.altmetric-hidden)').length === 0) { $(this).closest('.widget').hide(); } $(this).closest('.wrapper').hide(); }); }); </script> <div class="ajax-content" data-src="https://editor.copernicus.org/similarArticles.php?article=73782&journal=10&isSecondStage=1&ajax=true"> </div> </div> <div class="auto-fixed-top px-1 mb-3 articleNavigation" data-fixet-top-target="#section1"> <button class="btn btn-success mb-3 btn-block" id="mathjax-turn"><i class="fal fa-function"></i> Turn MathJax on</button> <div class="widget dark-border m-0"> <div class="legend journal-contentLinkColor">Sections</div> <div class="content"> <ul class="toc-styling p-0"> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#abstract" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Abstract</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section1" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Introduction</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section2" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Data and methods</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section3" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Results and discussion</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section4" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Conclusions</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section5" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Data availability</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section6" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title"><span>Appendix A:</span> Comparison of forward model simulations at 4<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 5<span class="inline-formula"><sup>∘</sup></span> and 2<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 2.5<span class="inline-formula"><sup>∘</sup></span> resolutions</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section7" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title"><span>Appendix B:</span> Sensitivity to seasonal bias in prior emission estimates</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section8" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Author contributions</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section9" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Competing interests</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section10" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Acknowledgements</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section11" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Financial support</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section12" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">Review statement</a> </li> <li> <a href="https://acp.copernicus.org/articles/19/7859/2019/#section13" class="scrollto" data-fixed-element=".auto-fixed-top-forced.article-title">References</a> </li> </ul> </div> </div> </div> </div> </div> </div> </main>  <footer class="d-print-none version-2023"> <div class="footer"> <div class="container"> <div class="row align-items-center mb-3"> <div class="col-12 col-lg-auto text-center text-md-left title-wrapper"> <div id="j-header-footer" class="text-center text-md-left"> <div class="h1 text-center text-md-left"> Atmospheric Chemistry and Physics </div> <p>An interactive open-access journal of the European Geosciences Union</p> </div> </div> <div class="col-12 col-lg-auto text-center text-md-left pt-lg-2"> <div class="row align-items-center"> <div class="col-12 col-sm col-md-auto text-center text-md-left mb-3 mb-sm-0"> <span class="egu-logo"><a href="http://www.egu.eu/" target="_blank"><img src="https://contentmanager.copernicus.org/319373/10/ssl" alt="" style="width: 410px; height: 325px;" /></a></span> </div> <div class="col-12 col-sm text-center text-md-left"> <span class="copernicus-logo"><a href="https://publications.copernicus.org/" target="_blank"><img src="https://contentmanager.copernicus.org/319376/10/ssl" alt="" style="width: 1784px; height: 330px;" /></a></span> </div> </div> </div> </div> </div> </div> <div class="links pb-4 pt-4"> <div class="container"> <div class="row align-items-center"> <div class="col-12 col-xl-auto mt-3"> <div class="row align-items-start align-items-lg-center"> <div class="col-12 mb-3 mb-md-0 pl-md-0 text-center text-md-left"><a href="https://creativecommons.org/licenses/by/4.0/" target="_blank"><i class="fab fa-creative-commons fa-lg mr-1"></i><i class="fab fa-creative-commons-by fa-lg"></i></a> All site content, except where otherwise noted, is licensed under the <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank">Creative Commons Attribution 4.0 License</a>.</div> </div> </div> <div class="col-12 text-center text-md-left col-lg-auto mt-3"> <div class="row align-items-center"> <div class="col d-md-none px-0"></div> <div class="col-auto pr-1"><a href="https://www.atmospheric-chemistry-and-physics.net/about/contact.html">Contact</a></div> <div class="col-auto px-1">|</div> <div class="col-auto px-1"><a href="https://www.atmospheric-chemistry-and-physics.net/imprint.html">Imprint</a></div> <div class="col-auto px-1">|</div> <div class="col-auto px-1"><a href="https://www.copernicus.org/data_protection.html" target="_blank">Data protection</a></div> <div class="col-auto pl-2"></div> <div class="col d-md-none px-0"></div> </div> </div> </div> </div> </div> </footer> </body> </html>

CINXE.COM

ACP - Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015