[MITgcm-devel] seaice adjoint and EVP

[Jinlun Zhang]

Hey Dimitris, nice job! Could be a very nice paper.
Jinlun

Dimitris Menemenlis wrote:

> Martin and Jinlun, now that the snow and zmin stuff has been sorted 
> out, I am rerunning a timestep test for the EVP solver and it looks 
> like Jinlun's guess is correct.  Some figures comparing sea-ice fields 
> after 2 months integration of LSR vs EVP with time steps of 1, 10, 20, 
> 30, and 60 s time steps:
> ftp://ecco2.jpl.nasa.gov/data1/arctic/output/tests/figs
>
> ftp://ecco2.jpl.nasa.gov/data1/arctic/output/tests/figs/AREA4320.ps
> shows that EVP solution tends to LSR as time step is decreased.
>
> ftp://ecco2.jpl.nasa.gov/data1/arctic/output/tests/figs/UICE4320.ps
> shows that striation goes away as time step is decreased
>
> ftp://ecco2.jpl.nasa.gov/data1/arctic/output/tests/figs/maskedUICE4320.ps
> is same figure but velocity where AREA=0 has been masked
>
> so does this all mean that for 18-km resolution LSR solver is preferable?
>
>> 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.
>