[MITgcm-support] RBCS for sea ice boundary conditions

[Martin Losch]

Hi Alan,

I think that the combination pkg/seaice + obcs is far from complete. There are a lot of a hacks and adhoc solutions that may work in some cases, but not in all. There’s even the option to add a sponge for seaice parameters (which I have never tried, but it is tested in verification experiment seaice_obcs.sponge).

I have been OK with solutions, where I directly implemented Neumann boundary conditions (dh/dn = 0) in the obcs_apply_*.F files on boundaries, where I know that there is only outflow (usually in free drift). For inflow conditions it’s much harder, but the Neumann conditions also help. One of the problems is that the boundary conditions should not only include (uice,vice,heff,hsnow,area), but also derived variables like ice strength (variable “press" in the code), which is not properly done. For example, it would make sense to have free slip along open boundaries, meaning zero shear and bulk viscosities along open boundaries.

It should be straightforward to extend rbcs to seaice (not done, you’d have to do it yourself).

Martin

> On 1. Nov 2022, at 23:55, Alan Gaul <agaul at mit.edu> wrote:
> 
> Hi everyone,
>  
> I am wondering if sea ice boundary conditions (area, thickness, velocities) work with the RBCS package? I see that the SEAICE package works with the OBCS package, but am curious if anyone has used SEAICE and RBCS together. I’m curious because l’ve been struggling to keep sea ice from building up at the boundary when using SEAICE + OBCS (my boundary conditions are interpolated from SOSE output), and regarding a previous support thread linked below, perhaps a relaxation region might help solve this.
>  
> Thank you,
> Alan
>  
> P.S. I have tried a couple of fixes, for instance going to OBCS_OPTIONS and defining first OBCS_SEAICE_AVOID_CONVERGENCE and then next also defining OBCS_SEAICE_COMPUTE_UVICE, but these did not seem to help.
>  
> Previous support thread:
> http://mailman.mitgcm.org/pipermail/mitgcm-support/2020-May/012518.html <http://mailman.mitgcm.org/pipermail/mitgcm-support/2020-May/012518.html>
>  
> ------------------------------------------
>  
> <OBCS_OPTIONS.h><SEAICE_OPTIONS.h><CPP_OPTIONS.h>_______________________________________________
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