[Mitgcm-support] Re: some progress

[mitgcm-support at dev.mitgcm.org]

Hello,

Although I have already talked with Jean-Michel about this, I am sending
this e-mail for anyone interested in the discussion.

The mitphysics package so far has only been tested with a rigidlid, with
40 levels in the vertical. The problems we have encountered might arise
(according to Jean-Michel) from filetering (FFT or shapiro) after calling
the elliptic solver instead of before. 

Cheers,

Olivier

On Tue, 4 Dec 2001, Jean-Michel Campin wrote:

> Hello,
> 
> I've found that exactConserv is really necessary when we 
> use free-surface + filter U,V :
> 
> with Held & Suarez, 128x64x20 and no Shapiro filter for T,
> 1) no exactConserv => the model blows up with deltaT=450s, 
> and with deltaT=300s, the minimum potential temperature 
> becomes occasionally very low (less than 50.K).
> 2) turning on exactConserv solve this Pb and produce
> less noise in W fields.
> 
> Still too early to claim that this fixed the problem of
> low pot.T near the pole, but it might be the case:
> 1) in pre38, the U,V filters (Shap & FFT) were not applied after 
> SOLVE_FOR_P but before. Then exactConserv is not necessary.
> 2) when I don't use exactConserv but filtered (shapiro) T,
> the mimimum temperature is OK.
> This explains why Daniel did not have this problem when
> he run  H&S with 20 levels in last may. 
> 
> Olivier, are you using the rigid-lid or the free surface ?
> 
> See you,
> 
> Jean-Michel
>