[MITgcm-support] How to reduce zonal velocity to zero in regions where temperature is lower than a critical value?

[Martin Losch]

Hi Yanhong,

I think that you have the right idea. Your term looks like a restoring term to zero (0 - vVel)*ksol and provided that you actually use apply_forcing_u (check if the preprocessed file appy_forcing.f contains your code still), it should work. Try with k_sol=1/deltaT (which should almost be like setting uVel to zero in the absence of other forcing) or k_sol = 1/(2*deltaT) to see if there’s any effect.

A different way without editing the main code would be to use the rbcs package, where you could specify a field of ksol and add a condition in rbcs_add_tendency.F, maybe that’s a little “safer”?

Martin


> On 10. Oct 2023, at 04:05, 赖燕红 <yhlai at pku.edu.cn> wrote:
> 
> Hello everyone!
> 
> 
> 
> I want to reduce u and v to zero in regions where the temperature is lower than 1700 K.
> 
> I tried to realize this goal by adding a linear drag in model/src/apply_forcing.F,
> 
> and the following codes are added in the subroutine APPLY_FORCING_U
> 
> 
> 
> %%%%%%%%%%%%
> 
>       _RL     T_sol
>       _RL     k_sol
> 
>       T_sol = 1700
>       k_sol = 1/86400
> 
> 
> 
>        DO j=0,sNy+1
>         DO i=1,sNx+1
>          IF ( theta(i,j,k,bi,bj) .LE. T_sol ) THEN
>           gU_arr(i,j) = gU_arr(i,j)
>      &      -uVel(i,j,k,bi,bj)*k_sol
>          ENDIF
>         ENDDO
>        ENDDO
> %%%%%%%%%%%
> But these codes seems do not work, and results are the same to the case without these additional codes, 
> that is to say U in regions with T<T_sol did not reduce to zero,
> Do you know what's wrong with these codes?
> Or is it possible to directly set the velocity equal to zero in regions where temperature below 1700 K ?
>  
> 
> Looking forward to your suggestions! Thanks in advance.
> 
> Best,
> 
> Yanhong 
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