[MITgcm-support] ice layer modeling -> cube corners?

[Dimitris Menemenlis]

Elja, the correct overlap in your case is OLx=Oly=8, I think.   You  
can test this by gradually increasing the overlap for a very short  
problem without optimization, until the pickup files are bit- 
identical.  But I don't think that this is what causes trouble at the  
corners.  The change in the solution from OLx 5 to 8 will be very small.

The corners of the cube have smaller dimensions than the rest of the  
cube so it's easier to violate CFL conditions.  What are your typical  
velocities, UVEL, VVEL, WVEL, relative to your grid dimensions, dx,  
dy, dz?

In your output file, do:
grep advcfl_ STDOUT.0000

If any of these values gets much larger than 1, then you may have to  
decrease your deltaT even further.

But deltaT is already quite small in your case if I remember correctly  
so this may not be the problem.

A second possibility is that sea ice model will not work at the  
corners.  All the tests that I have run with sea ice model, the ice  
never gets close to the corners.  In particular, the metric terms are  
ignored in the sea ice dynamics, so close to the corners I have no  
idea what will happen.  Also, I don't think that the ice momentum  
equations are compatible with corners.

Does anyone else on this list have experience with running the sea ice  
model across the cube corners?

One thing that you can do to test above hypothesis is to turn off sea  
ice dynamics and see if it helps.

SEAICEuseDYNAMICS  = .FALSE.,

in data.seaice

Dimitris Menemenlis
DMenemenlis at gmail.com

On Jul 18, 2008, at 6:00 AM, Elja Huibregtse wrote:

> Unfortunately, I still didn't find the solution to fix my unstable  
> ocean+ice model. While checking the data, I found, however, that  
> velocity-fields show deviant behavior at the corners of the cube (I  
> use a cubed sphere configuration). I attached one horizontal  
> velocity plot, where this behavior is clearly visible. The model  
> becomes, as expected, unstable in one of these 'corner-regions' and  
> blows up.
>
> Could there be something wrong with the coupling between the tiles?  
> Or do I need a larger overlap (in my case: OLx=Oly=5)?
> Do you have any idea what is wrong and how to fix it?