[MITgcm-support] Fwd: Inter-tile discontinuities

[Martin Losch]

Hi Enrico,

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).
I also suggest to increase the number of nonlinear iterations to 10 (SEAICEnonLinIterMax, default is 2). These unfortunate defaults are part of an issue (<https://github.com/MITgcm/MITgcm/issues/171>) on github, but I never got around to changing them to something more sensible (and nobody seems to care).

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 (<https://mitgcm.readthedocs.io/en/latest/phys_pkgs/seaice.html#more-stable-variants-of-elastic-viscous-plastic-dynamics-evp-mevp-and-aevp>)

Martin

> On 29. Oct 2019, at 14:42, Pochini, Enrico <epochini at inogs.it> wrote:
> 
> Dear all,
> 
> (I've attached the file as gdrive link..)
> 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.
> What could cause this issue?
> 
> Thanks,
> 
> Enrico
>  results24.nc
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