[MITgcm-support] Question About Sea Surface Height (Eta) Behavior in MITgcm

[Jordi Iglesias]

Dear MITgcm community,

Over the past few months, I’ve been struggling to achieve realistic sea 
surface height ("Eta") results in my MITgcm simulations. I’ve tried 
several configurations,including non-hydrostatic, quasi-non-hydrostatic, 
and nonlinear free surface options, but the SSH output often differs 
significantly from the parent model (the Copernicus Mediterranean 
analysis, MEDSEA). I’ve attached an example and also shared a link to 
illustrate the issue. I have tides configured, and the ssh is 
initialized from MEDSEA data. However, when I compare the SSH output 
with the parent model (or with a ROMS simulation, for example), it 
appears to oscillate around a constant value that doesn’t evolve much 
over time, or changes are very small.

A summary of my configuration: Horizontal resolution: 1.6 km, NW 
Mediterranean Sea, Atmospheric forcing: ECMWF, initial ssh set with 
pSurfInitFile, SphericalPolarGrid, quasiHydrostatic = .TRUE., 
nonlinFreeSurf = 3, rigidLid = .FALSE., implicitFreeSurface = .TRUE.,

If any additional parameters would help diagnose the issue, I’d be happy 
to provide them.

The temperature, salinity, and velocity fields are generally in good 
agreement with ROMS and MEDSEA, but I’d really like to improve the SSH 
performance. Has anyone encountered a similar issue or found strategies 
to improve SSH in MITgcm?

Thanks in advance for your help!

Best regards,
Jordi

https://saco.csic.es/s/c2fSgN5RWPRcDSQ

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