[MITgcm-devel] seaice adjoint and EVP

[Martin Losch]

Hi Jinlun,

I am using daily forcing, so that's different from Dimitris' Arctic  
setup as well.
I agree, the noise seems to be very resolution dependent.

I may try you suggestion with the resolution.

On a different note: I have been looking at yield curves, and it  
turns out that the evp-yield curves are almost perfect (I use 36  
snapshots every 10days for the first year of integration and tere are  
maybe 2 or 3 points that do not lie on the ellipse exactly). On the  
other hand the lsr-yield curves have far more points within this  
ellipse. I went back to you 1997 JGR paper and there you show yield  
curves with a few points within the ellipse as well (figure 10 with  
100 pseudo time steps). Is that picture acceptable (because if it is,  
then my yield curves are, too)?

Martin
On 26 May 2007, at 06:37, zhang at apl.washington.edu wrote:

> Martin,
>
> Are you using daily forcing? What is the time step? I wonder what  
> makes
> the problem go away. Maybe this thing is very resolution sensitive.  
> Do you
> want to try to artificially reduce the grid size, like adding lines  
> like
> DX*0.5 in the code?
>
> Jinlun
>
>> Hi there,
>> I am about to go home for an extended weekend, but I have give you
>> the latest news on EVP:
>>
>> I have tried to reproduce Dimitris' stripes in a configuration that
>> is similar to his: it's basically Ruediger Gerdes' Arctic grid:
>> rotated spherical grid with 1/4th degree resolution, so approximately
>> 25 to 27km resolution. This is a little coarser than Dimitris 18km,
>> but that's what I have. It's basically the grid of the AWI
>> contribution to AOMIP.
>>
>> The run is terrible because we don't have open boundaries, the
>> initial conditions are very noisy and the surface forcing has all
>> sorts of funny things in it, eg. a nice jump across the 0-meridian,
>> which is also impressed onto the surface fields in the run, oh well.
>>
>> But I do not see the stripines or noise that Dimitris sees in his evp
>> solution (I have 180 days by now). In fact with the default LSRerror
>> = 1e-4, the yield curves of the EVP solution are much better than
>> those of the LSR solution. I'll make some netcdf files available,
>> once these runs are finished (only one year runs, but still).
>>
>> Martin