<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi Enrico,<div class=""><br class=""></div><div class="">You can check the cfl criteria by looking at STDOUT.0000 (advu_cfl, advw_cfl etc). You don’t say anything about your vertical resolution, but if it is fine enough to use non-hydrostatic then you are quite possibly violating the CFL criteria in the vertical velocity. </div><div class=""><br class=""></div><div class="">For testing purposes you may want to turn nonHydrostatic off (and maybe consider whether 0.5 degree runs can properly represent non-hydrostatic effects). That may not help your cfl criteria, but the model will run faster. </div><div class=""><br class=""></div><div class="">Cheers, Jody<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 22 Oct 2019, at 06:53, Pochini, Enrico <<a href="mailto:epochini@inogs.it" class="">epochini@inogs.it</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">Dear MITgcm support group,</div><div class=""><br class=""></div><div class="">I'm trying to develop a model of the Ross Sea for my PhD. Until now I've generated the grid and I've started testing it with constant atmospheric forcing, boundary conditions, and initial conditions, but I'm crashing a few kilo-seconds after initialization.</div><div class=""><br class=""></div><div class="">To generate it I followed what is written in this page:<br class=""></div><div class=""><a href="https://github.com/knaughten/mitgcm_python/wiki/Creating-a-new-MITgcm-domain#grid" target="_blank" class="">https://github.com/knaughten/mitgcm_python/wiki/Creating-a-new-MITgcm-domain#grid</a></div><div class=""></div><div class=""><br class=""></div><div class="">However even minimal runs with disabled SHELFice, OBCS packages, imposing no surface forcing, with uniform initial conditions, still it develops instabilities and crashes.<br class=""></div><div class=""><br class=""></div><div class="">I'm absolutely new to MITgcm and ocean modeling and I would need your help to understand what is causing the issues, in particular if the bathymetry has some pathologies or the (spherical) grid violates CFL somewhere .. (?) I'm using 150 seconds timestep, 0.5 degree grid.<br class=""></div><div class=""><br class=""></div><div class="">I've attached four minimal test outputs, with and without ice shelf, with and without smoothing of ice shelf draft and bathymetry. The number with the file is the last iteration printed. <br class=""></div><div class="">Thank you.<br class=""></div><div class=""><br class=""></div><div class="">Best regards,<div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:rgb(245,245,245);padding:5px;color:rgb(34,34,34);font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid rgb(221,221,221);line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1SM5mtzq3WgF61EbLh4404N5cz3czIuSI/view?usp=drive_web" target="_blank" style="display:inline-block;max-width:366px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0;border:none" class=""><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png" class=""> <span dir="ltr" style="color:rgb(17,85,204);text-decoration:none;vertical-align:bottom" class="">file_support.tar.gz</span></a><img src="x-msg://ssl.gstatic.com/ui/v1/icons/common/x_8px.png" style="opacity: 0.55; cursor: pointer; float: right; top: -1px; display: none;" class=""></div></div><div class=""><br class=""></div><div class="">Enrico Pochini<br class=""></div><div class=""><br class=""></div><div class="">PhD student, University of Trieste, Italy<br class=""></div></div>
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<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; color: rgb(0, 0, 0); font-family: 'Lucida Sans Typewriter'; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div style="word-wrap: break-word;" class=""><span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px; color: rgb(0, 0, 0); font-family: 'Lucida Sans Typewriter'; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-indent: 0px; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px;"><div class="">--</div><div class="">Jody Klymak </div><div class=""><a href="http://web.uvic.ca/~jklymak/" class="">http://web.uvic.ca/~jklymak/</a></div><div class=""><br class="khtml-block-placeholder"></div><div class=""><br class="khtml-block-placeholder"></div><br class="Apple-interchange-newline"></span></div></span><br class="Apple-interchange-newline">
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