[MITgcm-devel] Re: downslope pkg

[Jean-Michel Campin]

Hi Martin,

I added something similar to what you proposed, testing for kSurfC
which does not seem so different from kTopC, apart where the column
is empty, but is available in standard GRID.h header file.

I looked briefly to the interface between shelfice pkg and the 
main code, and think that with 1 more shelfice S/R call
from the middle of ini_mask_etc.F (where hFacC is modified by
R_shelice), we could remove the pieces of code in ini_depth.F and in 
ini_mask_etc.F and put them in this new S/R (just need to break 
the bi,bj loops in 2 blocks, in ini_mask_etc.F);

Also, why is shelfIceFile in PARAMS.h and appears in parameter file "data" ?
A more logical place would be in SHELFICE.h and data.shelfice.
At the time when shelfice pkg was checked-in, we already have (Oct 2004)
moved packages_readparms call before ini_depth call in initialise_fixed.F

Cheers,
Jean-Michel

On Fri, Sep 05, 2008 at 10:41:16PM +0200, Martin Losch wrote:
> Hi Jean-Michel,
> the masking is absolutely necessary for the shelfice package in the  
> current implementation (who gave this package this stoopid name, some  
> German idiot!), because otherwise the model integrates some ridiculous 
> density (for Theta=Salt=0, or even worse from some other arbitrary Theta 
> and Salt) from the top for phiHyd. When useShelfice=.true. you are 
> supposed to provide a reference pressure at the bottom of the ice shelf 
> and integrating phiHyd from the very top (k=1) is not necessary. JMD95P 
> and MDJFW should work with shelfice, too, for this reason.  I don't know 
> about the downSlope package. That one was not around, when I implemented 
> shelfice.
> Without the masking, one would have to use if statements in the ij-loops 
> for the phiHyd intergration to determine, where the real intergration of 
> phiHyd is supposed to start; not good. Alternatively, one could only mask 
> alphaRho in the ice shelf, like this:
>         IF ( useShelfIce ) THEN
>          DO j=jMin,jMax
>           DO i=iMin,iMax
>            IF ( kTopC(I,J,bi,bj) .GE. k ) alphaRho(i,j) = alphaRho 
> (i,j)*maskC(i,j,k,bi,bj)
>           ENDDO
>          ENDDO
>         ENDIF
> Do you have a better idea?
>
> Martin
>
> On 5 Sep 2008, at 18:31, Jean-Michel Campin wrote:
>
>> Hi Michael,
>>
>> I found a problem with shelfice & down_slope pkgs:
>> looks like useShelfIce is masking the density (in CALC_PHI_HYD)
>> so that we will have a problem when using an EOS directly function
>> of pressure (e.g.: JMD95P). I looked to
>> MITgcm_contrib/high_res_cube/data.hr
>> and it's not the case (EOS=JMD95Z).
>> Can you confirm that you are not using an EOS directly function
>> of pressure ?
>>
>> Otherwise, how is the test going ?
>>
>> I cc this to the devel list, so that Martin will know why I will
>> bother him to remove this masking with useShelfIce ...
>>
>> Cheers,
>> Jean-Michel
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>