[MITgcm-devel] seaice adjoint and EVP

[Jinlun Zhang]

It seems there is some kind of instability shown in the sigma plots in 
the marginal ice zone. I wonder if a smaller EVP timestep, close to that 
of a fully explicit method, would get rid of this problem. The time step 
for FEX is 1 s or less.

Jinlun

Dimitris Menemenlis wrote:

> Martin,
>
>> I have corrected the bug in seaice_ocean_stress (I am wondering if 
>> this will
>> fix the problem that Dimitris has with evp. I don't think so, but 
>> there is
>> always hope o:), and updated lab_sea but not the
>
>
> Unfortunately the stripes are still there.  This is not with very 
> latest code. It is yesterday's pkg/seaice code with
>
>> columbia15: diff seaice_ocean_stress.F 
>> ../MITgcm/pkg/seaice/seaice_ocean_stress.F 184c184
>> <           fuIceLoc=HALF*( DWATN(I,J,bi,bj)+DWATN(I-1,J,bi,bj) )*
>> ---
>>
>>>           fuIceLoc=HALF*( DWATN(I,J,bi,bj)+DWATN(I,J+1,bi,bj) )*
>>
>> 195c195
>> <           fvIceLoc=HALF*( DWATN(I,J,bi,bj)+DWATN(I,J-1,bi,bj) )*
>> ---
>>
>>>           fvIceLoc=HALF*( DWATN(I,J,bi,bj)+DWATN(I+1,J,bi,bj) )*
>>
>
> So I am assuming EVP will eventually crash as before.
> Figure comparing evp to lsr solution is here
> http://ecco2.jpl.nasa.gov/data1/arctic/output/tests/evp/evp_vs_lsr.ps.gz
> Directory
> http://ecco2.jpl.nasa.gov/data1/arctic/output/tests/evp/
> contains pkg/seaice output, including sigmas, matlab routine to 
> read/plot and an additional figure
> http://ecco2.jpl.nasa.gov/data1/arctic/output/tests/evp/evp.ps.gz
> of all the evp fields
> sigma* colorscale is chosen to emphasize open water.
> character of sigma1 over open water is much different from sigma2 and 
> sigma12, is this what you expect?
>
> D.
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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