[MITgcm-support] unrealistic model results in a regional model

[Fanglou Liao]

Hi Matt

I've solved the unphysical noisy problem. Thank you very much,

FL
________________________________
From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of Fanglou Liao <fanglou.liao at unswalumni.com>
Sent: Wednesday, November 26, 2025 5:10 PM
To: mitgcm-support at mitgcm.org <mitgcm-support at mitgcm.org>
Subject: Re: [MITgcm-support] unrealistic model results in a regional model

Hi Matt

Thank you so much for your response. I've tried your advices, and found that  U, V boundary conditions caused the noisy patterns and leading to unphysical results. Keeping only normal velocity (i.e., v=0 along the east boundary and u=0 along the south one; T, S were kept) at the open boundaries does not solve the problem. I've also tried to "make the bathymetry flat in the normal direction for several (6) grid cells", but the noisy patterns still occured.


restoring sponge time was also tried as suggested.

Best,

FL
________________________________
From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of Fanglou Liao <fanglou.liao at unswalumni.com>
Sent: Tuesday, November 25, 2025 9:38 PM
To: MITgcm Support <mitgcm-support at mitgcm.org>
Subject: [MITgcm-support] unrealistic model results in a regional model

Dear MITgcm support

I am a new MITgcm user. I am building a regional ocean model with mitgcm, and have some problems with the model results, which I guess are associated with the open boundaries (East and South).  This model is of 0.03 deg, with initial (T, S, U, V) and open boundary conditions are interpolated from CMEMS reanalysis (0.083 deg). The external forcing are from ERA5. The Δt = 45 seconds. The model results are unrealistic, with small-scale patterns appear (attached), and the SST even dropped below 0 after a few days. When I closed the east and south boundaries, these problems disappeard.  Could you please kindly help me check my files attached and give me some advices?

Thank you very much

FL
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