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<!DOCTYPE HTML><html lang="en"><head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8" /> <link rel="stylesheet" type="text/css" href="https://www.giss.nasa.gov/css/css2104.css" media="all" /> <title>Pubs.GISS: Schwarzwald et al. 2023: Understanding CMIP6 biases in the representation of the greater Horn of Africa...</title> <link rel="stylesheet" type="text/css" href="/css/pubs.css" media="all" /> <script src="/js/pubs.js" async="async"></script> <link rel="apple-touch-icon" href="/gfx/apple-touch-icon-180x180.png" /> <link rel="apple-touch-icon-precomposed" href="/gfx/apple-touch-icon-180x180.png" /> <link rel="apple-touch-icon" sizes="192x192" href="/gfx/apple-touch-icon-192x192.png" /> <link rel="apple-touch-icon" sizes="180x180" href="/gfx/apple-touch-icon-180x180.png" /> <link rel="apple-touch-icon" sizes="152x152" href="/gfx/apple-touch-icon-152x152.png" /> <link rel="apple-touch-icon" sizes="128x128" href="/gfx/apple-touch-icon-128x128.png" /> <link rel="apple-touch-icon" sizes="76x76" href="/gfx/apple-touch-icon-76x76.png" /> <meta name="orgcode" content="611" /> <meta name="rno" content="Gavin.A.Schmidt.1" /> <meta name="content-owner" content="Robert.B.Schmunk.1" /> <meta name="webmaster" content="Robert.B.Schmunk.1" /> <meta name="viewport" content="width=956, initial-scale=1" /><script id="_fed_an_ua_tag" src="https://dap.digitalgov.gov/Universal-Federated-Analytics-Min.js?agency=NASA&subagency=GISS&yt=true&dclink=true" async="async"></script> </head><body> <div id="bkg1"><div id="bkg2"></div></div> <div id="page"> <div class="hidden"> <a href="#content" title="Go to Main Content" accesskey="2">Go to Main Content (Accesskey 2)</a><br /><a href="#nav" title="Go to Site Menu" accesskey="3">Go to Site Menu (Accesskey 3)</a></div> <div id="header"> <div id="headerlogo"> <a href="https://www.nasa.gov/"><img src="https://www.giss.nasa.gov/gfx/2013/nasa_x2.png" alt="NASA Logo, National Aeronautics and Space Administration" style="width:140px;height:98px" /></a></div> <div id="centername"> <h1><a href="https://www.nasa.gov/">National Aeronautics and Space Administration</a></h1> <h2><a href="https://www.giss.nasa.gov/">Goddard Institute for Space Studies</a></h2></div> <div id="hierarchy"> <h2><a href="https://www.nasa.gov/goddard/">Goddard Space Flight Center</a><br /><a href="https://science.gsfc.nasa.gov/sci">Sciences and Exploration Directorate</a><br /><a href="https://science.gsfc.nasa.gov/earth">Earth Sciences Division</a></h2></div></div> <div id="paper"> <div id="content"><div id="cpad"><h2>Publication Abstracts</h2> <h3>Schwarzwald et al. 2023</h3> <p>Schwarzwald, K., L. Goddard, R. Seager, M. Ting, and <span class="gissauthor">K. Marvel</span>, 2023: Understanding CMIP6 biases in the representation of the greater Horn of Africa long and short rains. <cite>Clim. Dyn.</cite>, <b>61</b>, no. 3-4, 1229-1255, doi:10.1007/s00382-022-06622-5.</p> <p>The societies of the Greater Horn of Africa (GHA) are vulnerable to variability in two distinct rainy seasons, the March-May 'long' rains and the October-December 'short' rains. Recent trends in both rainy seasons, possibly related to patterns of low-frequency variability, have increased interest in future climate projections from General Circulation Models (GCMs). However, previous generations of GCMs historically have poorly simulated the regional hydroclimate. This study conducts a process-based evaluation of simulations of the long and short rains in CMIP6, the latest generation of GCMs. Key biases in CMIP5 remain or are worsened, including long rains that are too short and weak and short rains that are too long and strong. Model biases are driven by a complex set of related oceanic and atmospheric factors, including simulations of the Walker Circulation. Biased wet short rains in models are connected with Indian Ocean zonal sea surface temperature (SST) gradients that are too warm in the west and convection that is too deep. Models connect equatorial African winds with the strength of the short rains, though in observations a robust connection is primarily found in the long rains. Model mean state biases in the timing of the western Indian Ocean SST seasonal cycle are associated with certain rainfall timing biases, though both biases may be due to a common source. Simulations driven by historical SSTs (AMIP runs) often have larger biases than fully coupled runs. A path towards using biases to better understand uncertainty in projections of GHA rainfall is suggested.</p> <ul style="padding-top: 0"> <li><a href="http://dx.doi.org/10.1007/s00382-022-06622-5">Go to journal article webpage</a></li> </ul> <p><b>Export citation:</b> [ <a href="javascript:void(0)" onclick="showBibtexCite(1)" onkeypress="showBibtexCite(1)">BibTeX</a> ] [ <a href="javascript:void(0)" onclick="showRisCite(1)" onkeypress="showRisCite(1)">RIS</a> ]</p> <div id="bibtex" class="bibtex"><h4>BibTeX Citation</h4> <pre>@article{sc01800d, author={Schwarzwald, K. and Goddard, L. and Seager, R. and Ting, M. and Marvel, K.}, title={Understanding CMIP6 biases in the representation of the greater Horn of Africa long and short rains}, year={2023}, journal={Climate Dynamics}, volume={61}, number={3-4}, pages={1229--1255}, doi={10.1007/s00382-022-06622-5}, } </pre> <p style="font-weight:bold;text-align:center">[ <a href="javascript:void(0)" onclick="hideBibtexCite(1)" onkeypress="hideBibtexCite(1)">Close</a> ]</p></div> <div id="bibtexfade" class="bibtexfade" onclick="hideBibtexCite(1)" onkeypress="hideBibtexCite(1)" tabindex="0"></div> <div id="ris" class="ris"><h4>RIS Citation</h4> <pre>TY - JOUR ID - sc01800d AU - Schwarzwald, K. AU - Goddard, L. AU - Seager, R. AU - Ting, M. AU - Marvel, K. PY - 2023 TI - Understanding CMIP6 biases in the representation of the greater Horn of Africa long and short rains JA - Clim. Dyn. JO - Climate Dynamics VL - 61 IS - 3-4 SP - 1229 EP - 1255 DO - 10.1007/s00382-022-06622-5 ER - </pre><hr /> <p style="font-weight:bold;text-align:center">[ <a href="javascript:void(0)" onclick="hideRisCite(1)" onkeypress="hideRisCite(1)">Close</a> ]</p></div> <div id="risfade" class="risfade" onclick="hideRisCite(1)" onkeypress="hideRisCite(1)" tabindex="0"></div> <h4 class="goback"><a href="/year/2023.html">• Return to 2023 Publications</a></h4> <h4 class="goback"><a href="/">• Return to Publications Homepage</a></h4> <div class="clear"></div></div></div> <div id="nav"><h3>Site Menu</h3> <ul id="mnav"> <li><a href="https://www.giss.nasa.gov/">GISS Home</a></li> <li><a href="https://www.giss.nasa.gov/research/">News & Features</a> <ul class="mnav2"> <li><a href="https://www.giss.nasa.gov/research/">News & Features Overview</a></li></ul></li> <li><a href="https://www.giss.nasa.gov/projects/">Projects & Groups</a> <ul class="mnav2"> <li><a 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