<div dir="ltr"><div>Hi Martin,</div><div><br></div><div>thank you for your answer. I used the data.seaice and SEAICE_OPTIONS.h from verification/lab_sea. I've tried to set the parameters as you said and I also tried with SEAICEuseKrylov=.TRUE., which automatically sets LSR_ERROR=1.E-12 and SEAICEnonLinIterMax=10. However I still have the issue.</div><div>I attach a link to the code and namelist which I used. In STDOUT it seems that the solver for the sea ice dynamics does not converge. <br></div><div>Eventually the model crashes...</div><div><br></div><div>Enrico<br></div><div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1IdUfelBlDrti9iK5RysnXMjYgSaH0-LW/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png"> <span dir="ltr" style="color:#15c;text-decoration:none;vertical-align:bottom">results72.nc</span></a></div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1VrUQut_oD9yWhV9v4QHQG4mZ_-miETmc/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png"> <span dir="ltr" style="color:#15c;text-decoration:none;vertical-align:bottom">results_seaice72.nc</span></a></div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1DjQkpt4AAgPO8U_x_yDE1S3YOJqtCq76/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png"> <span dir="ltr" style="color:#15c;text-decoration:none;vertical-align:bottom">sysdiag_48.nc</span></a></div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1HDxBg7PnZ1h-WcqSdInaDOBC47LLSUfJ/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png"> <span dir="ltr" style="color:#15c;text-decoration:none;vertical-align:bottom">SEAICE_OPTIONS.h</span></a></div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1QkgiKhPcp7yJ0dI1Xk3rb61U_CrGNmY6/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10_generic_list.png"> <span dir="ltr" style="color:#15c;text-decoration:none;vertical-align:bottom">SEAICE_SIZE.h</span></a></div><br><div class="gmail_chip gmail_drive_chip" style="width:396px;height:18px;max-height:18px;background-color:#f5f5f5;padding:5px;color:#222;font-family:arial;font-style:normal;font-weight:bold;font-size:13px;border:1px solid #ddd;line-height:1"><a href="https://drive.google.com/a/inogs.it/file/d/1Lw4bM0-T1IH-0ysFH7SgsH8RA7FQjnP7/view?usp=drive_web" target="_blank" style="display:inline-block;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;text-decoration:none;padding:1px 0px;border:medium none;width:100%"><img style="vertical-align: bottom; border: none;" src="https://ssl.gstatic.com/docs/doclist/images/icon_10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<br>
this is most likely linked to the dynamics solver. For historical reasons, the default parameters are not very fortunate. Without knowing your “data.seaice” and “SEAICE_OPTIONS.h”, I am guessing that you can fix this problem by reducing the linear tolerance (by setting LSR_ERROR to values of 1.e-5 or smaller).<br>
I also suggest to increase the number of nonlinear iterations to 10 (SEAICEnonLinIterMax, default is 2). These unfortunate defaults are part of an issue (<<a href="https://github.com/MITgcm/MITgcm/issues/171" rel="noreferrer" target="_blank">https://github.com/MITgcm/MITgcm/issues/171</a>>) on github, but I never got around to changing them to something more sensible (and nobody seems to care).<br>
<br>
Alternatively you could use the EVP code, but then make sure that you use at least mEVP (again, the defaults are not great), see the documentation (<<a href="https://mitgcm.readthedocs.io/en/latest/phys_pkgs/seaice.html#more-stable-variants-of-elastic-viscous-plastic-dynamics-evp-mevp-and-aevp" rel="noreferrer" target="_blank">https://mitgcm.readthedocs.io/en/latest/phys_pkgs/seaice.html#more-stable-variants-of-elastic-viscous-plastic-dynamics-evp-mevp-and-aevp</a>>)<br>
<br>
Martin<br>
<br>
> On 29. Oct 2019, at 14:42, Pochini, Enrico <<a href="mailto:epochini@inogs.it" target="_blank">epochini@inogs.it</a>> wrote:<br>
> <br>
> Dear all,<br>
> <br>
> (I've attached the file as gdrive link..)<br>
> I'm having issues with the SEAICE module i guess. After I activated it I started to observe discontinuities at tiles edge, where the marine ice is present. The discontinuities grow in time. I see discontinuities in surface fields and shallower levels of 3D fields.<br>
> What could cause this issue?<br>
> <br>
> Thanks,<br>
> <br>
> Enrico<br>
>  <a href="http://results24.nc" rel="noreferrer" target="_blank">results24.nc</a><br>
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