<div dir="ltr">Hello Daniel,<div><br></div><div>In the past, I successfully configured a regional high-resolution Kara Sea model where I used a pure z coordinate and a non-linear free surface + SEAICE package. The model is still being used and working, giving good results.</div><div><br></div><div>You are right about possible issues with sea ice if it is rather thick while you have fine vertical resolution of the upper layer. Because of that (+ sea-level oscillations due to tides, storm surges, etc) I used the thickness of the upper level equal to 5 m while using z coordinate, due to possible sea-ice thickness of 2-3 m in some locations in the Kara Sea + sea-level oscillations.</div><div><br></div><div>Kind Regards,</div><div>Stanislav Martyanov</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">вт, 22 сент. 2026 г. в 15:23, Daniel Goldberg <<a href="mailto:Dan.Goldberg@ed.ac.uk">Dan.Goldberg@ed.ac.uk</a>>:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1943404302537169274">
<div dir="ltr">
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
thanks J-M! i didn't know about the sIceLoadFac parameter either, so that will be an option.</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
best</div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
dan</div>
<div id="m_-4171627387327588117appendonsend"></div>
<hr style="display:inline-block;width:98%">
<div id="m_-4171627387327588117divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> MITgcm-support <<a href="mailto:mitgcm-support-bounces@mitgcm.org" target="_blank">mitgcm-support-bounces@mitgcm.org</a>> on behalf of Jean-Michel Campin <<a href="mailto:jmc@mit.edu" target="_blank">jmc@mit.edu</a>><br>
<b>Sent:</b> Tuesday, September 22, 2026 13:18<br>
<b>To:</b> <a href="mailto:mitgcm-support@mitgcm.org" target="_blank">mitgcm-support@mitgcm.org</a> <<a href="mailto:mitgcm-support@mitgcm.org" target="_blank">mitgcm-support@mitgcm.org</a>><br>
<b>Subject:</b> Re: [MITgcm-support] NLFS=4 with z coordinates.. and sea ice</font>
<div> </div>
</div>
<div><font size="2"><span style="font-size:11pt">
<div>Hi Dan,<br>
<br>
It should work, not used much without z*, precisely for the reason you mentioned,<br>
see also the Ocean modelling paper, doi:10.1016/j.ocemod.2008.05.005 :<br>
"Sea ice-ocean coupling using a rescaled vertical coordinate z*"<br>
<br>
Note that you could always bring back an inconsistent "levitating" sea ice with<br>
a recently added param (in "data", first namelist): sIceLoadFac=0., <br>
<br>
Cheers,<br>
Jean-Michel<br>
<br>
On Tue, Sep 22, 2026 at 11:18:26AM +0000, Daniel Goldberg wrote:<br>
> Hello!<br>
> <br>
> I am curious if anyone has used nonlinear free surface (NLFS=4) with z-coordinates and with the sea ice model?<br>
> <br>
> I suspect that it will be limited by the thickness of the top cell relative to the sea ice thickness, and am prepared to deal with surf_adjustment errors if they occur.<br>
> <br>
> But aside from this, Im wondering if there are any numerics/packages that simply won't work, of if i will get a RT error simply for trying this combination of parameters?<br>
> <br>
> Thanks!<br>
> dan<br>
> <br>
> --<br>
> Daniel Goldberg, PhD (he/him)<br>
> Reader in Glaciology<br>
> School of Geosciences, University of Edinburgh<br>
> Geography Building, Drummond Street, Edinburgh EH8 9XP<br>
> <a href="https://dngoldberg.github.io/" target="_blank">https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdngoldberg.github.io%2F&data=05%7C02%7C%7C108277bdc88f45caa62708df18a3a6a9%7C2e9f06b016694589878910a06934dc61%7C0%7C0%7C639256765027698491%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C80000%7C%7C%7C&sdata=htzz%2FkVcQq3bVzfj7yZUnzJkQ4cxs6b8tfc4P0kKf%2Fw%3D&reserved=0</a><br>
> <br>
> Note: My institution's virus protection makes any attachments of code source files unreadable. Please zip, rename, or share via cloud.<br>
> The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. Is e buidheann carthannais a th' ann an Oilthigh Dhùn Èideann, clàraichte an Alba, àireamh clàraidh SC005336.<br>
<br>
> _______________________________________________<br>
> MITgcm-support mailing list<br>
> <a href="mailto:MITgcm-support@mitgcm.org" target="_blank">MITgcm-support@mitgcm.org</a><br>
> <a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support" target="_blank">https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailman.mitgcm.org%2Fmailman%2Flistinfo%2Fmitgcm-support&data=05%7C02%7C%7C108277bdc88f45caa62708df18a3a6a9%7C2e9f06b016694589878910a06934dc61%7C0%7C0%7C639256765027717941%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C80000%7C%7C%7C&sdata=qEB1mI4nlGtIlb43g2K6bF9OviOKjoHA4Vv4wuBGBDg%3D&reserved=0</a><br>
<br>
_______________________________________________<br>
MITgcm-support mailing list<br>
<a href="mailto:MITgcm-support@mitgcm.org" target="_blank">MITgcm-support@mitgcm.org</a><br>
<a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support" target="_blank">https://eur02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailman.mitgcm.org%2Fmailman%2Flistinfo%2Fmitgcm-support&data=05%7C02%7C%7C108277bdc88f45caa62708df18a3a6a9%7C2e9f06b016694589878910a06934dc61%7C0%7C0%7C639256765027727930%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C80000%7C%7C%7C&sdata=8TK2xKJoJl3E%2Bg8ys0J%2B8jp80JSnsb%2B3ArFxTSlTQcM%3D&reserved=0</a><br>
</div>
</span></font></div>
</div>
_______________________________________________<br>
MITgcm-support mailing list<br>
<a href="mailto:MITgcm-support@mitgcm.org" target="_blank">MITgcm-support@mitgcm.org</a><br>
<a href="http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support" rel="noreferrer" target="_blank">http://mailman.mitgcm.org/mailman/listinfo/mitgcm-support</a><br>
</div></blockquote></div>