[MITgcm-support] Eta relaxation to obcs values

[Jean-Michel Campin]

Hi Hezi,

the simple OBCS (not with Orlanski) requires to specify:
- prescribed horizontal velocity
- prescribed T & S
the obcs_apply_eta.F subroutine is only there to control the
thickness layer that is used to compute horizontal transport at
the OB, when using NonLin-FreeSurface.
A relaxation on eta will have no effect on the mean SSH inside
the domain.

I would suggest (but it might be difficult to implement),
since you know the integrated E-P, that you try to prescribe
an equivalent inflow of salty (or fresh) water at the OB.

Jean-Michel

On Tue, Jul 26, 2005 at 02:23:05PM +0300, eliyahu biton wrote:

> Hello suporting list and others
> I'm trying to use real fresh water flux, and yet mantain reasonable sea 
> level values (as the evaporation rate from my basin's surface is ~2m/year).
> To do so I set the flag  useRealFreshWaterFlux to True, and I have one 
> OBCS in order to compansate the evaporation process (by relaxation of 
> the sea level values (eta) to the boundary values [set to zero by defult]) .
> I ran two experiments, one with non linear free surface and one with 
> linear free surface, both of them showed consistent dropping in sea 
> level and no relaxation to sea level boundary condition.
> I know that there is an option to use OBCSprescrib option where water 
> fluxes at the boundary are read from inputted files, but I would prefer 
> to use relaxation to sea level such that the fluxes at the boundary will 
> be calculated by the model.
> Any suggestion?
> thanks a lot, Eli.
> 
> -- 
> Eli Biton
> Dept. of Environmental Sciences,
> Weizmann Institute of Sciences,
> Rehovot, 76100
> Israel
> Tel: +972-8-9344924
> Fax: +972-8-9344124
> 
> 
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