[MITgcm-devel] more seaice

[Martin Losch]

Hello Dimitris,

FORCEX/Y at that point are air-ice-stress interactions, the  
coefficient ist call DAIRN. The ice-ocean stresses are put in later  
after the computation ETA,ZETA,Eij with the coefficent DWATN. So I  
think that at this point averaging does not make much sense: It would  
mean that the ice is driven both by wind over ice and wind over open  
water.

I think in the c-grid version I'll try to do it the way I find it  
intuitive: separate wind stress over ocean and ice and compute stress  
on ocean as the average of ice-ocean stress and wind stress (on the  
ocean). This is how it is done in the various coupled AWI ice models.

Martin

On Mar 6, 2006, at 7:54 PM, Dimitris Menemenlis wrote:

>> The way I understand this is that the stress on the ice is an  
>> average over ocean stress and ice stress ( the statement before  
>> FORCEX(I,J,bi,bj) = ...), whereas the stress over the ocean is  
>> just the ocean stress not weighted at all. I find this a little  
>> inconsistent if not wrong. I would think that these
>>  terms should be treated separately, with only the ice stress  
>> driving the
>> ice, right?
>
> Martin, yes it is inconsistent.  As Jinlun mentioned in an earlier  
> message, the
> original formulation for ocean stress, the one marked by CPP flag
> SEAICE_ORIGINAL_BAD_ICE_STRESS in ostres.F caused model  
> instabilities.  As a
> temporary fix, the presence of ice is ignored in the computation of  
> ocean
> surface stress, variables WINDX and WINDY.
>
> Regarding ocean stress at bottom of ice, variables FORCEX and  
> FORCEY, my understanding is that dynsolver assumes that thin ice  
> covers the open ocean everywhere, hence the weighted sum of ice- 
> covered and ice-free components in the computation of FORCEX and  
> FORCEY.  But I do not know whether and why this thin-ice assumption  
> is required nor what would be impact of setting the URT/VRT mask to  
> zero where AREA=0.
>
> Dimitris
>
> _______________________________________________
> MITgcm-devel mailing list
> MITgcm-devel at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-devel