[MITgcm-devel] seaice lsr

[Jinlun Zhang]

Martin,
The existing code is for relaxation using updated varaibles as soon as 
possible. If you do the change the code may converge slowly.
J

Martin Losch wrote:

> Hi there,
>
> I have found that the LSR solver is a little inconsistent (which  
> causes it to produce a slight assymetry with a symmetric domain and  
> forcing):
> the following lines:
>
>>           URT(I,J)=FXY(I,J,bi,bj)+AA3
>>      &          +UVRT1(I,J,bi,bj)*uIce(I,J-1,1,bi,bj)
>>      &          +UVRT2(I,J,bi,bj)*uIce(I,J+1,1,bi,bj)
>
> (and the corresponding ones for the vice equation) within a J-loop  
> cause URT to be computed from the updated uIce(I,J-1,1,bi,bj) and the  
> not yet updated uIce(I,J+1,1,bi,bj) (=uIce(I,J+1,3,bi,bj) at this  
> time). One could replace these lines by:
>
>>           URT(I,J)=FXY(I,J,bi,bj)+AA3
>>      &          +UVRT1(I,J,bi,bj)*uIce(I,J-1,3,bi,bj)
>>      &          +UVRT2(I,J,bi,bj)*uIce(I,J+1,3,bi,bj)
>
> which changes the results (lab_sea fails with cg2d=10), but then the  
> solution is symmetric, when it should be. Also this formulation  
> removes a dependency from the j-loop which impairs vectorization. Can  
> I change that?
>
> Martin
>
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-- 

Jinlun Zhang
Polar Science Center, Applied Physics Laboratory
University of Washington, 1013 NE 40th St, Seattle, WA 98105-6698

Phone: (206)-543-5569;  Fax: (206)-616-3142
zhang at apl.washington.edu
http://psc.apl.washington.edu/pscweb2002/Staff/zhang/zhang.html