[MITgcm-support] sponge layer

[Matthew Mazloff]

Hi David,

To restore to a value use obcs prescribe and make the location an  
"open boundary"; the model will set the field to the prescribed value  
at this open boundary at the end of every forward step.

Sponge layers are designed to allow a smooth transition to a  
prescribed value (I think they will still work with obcs_prescribe  
off).  For an artificial restoring force the difference between the  
model and the prescribed data (divided by some timescale) is used.   
The MITgcm does this with the timescale falling off linearly over the  
sponge layer thickness.

It is not clear to me if you want something else besides this?

-Matt


On Dec 14, 2005, at 4:59 PM, David Wang wrote:

> Hello...
>
> I'm going to implement "sponge layers" near artificial domain  
> boundaries within which model temperature may be restored to some  
> temperature climatology (say Levitus94) at different relaxation  
> timescales. I've already checked out the sponge layer option in the  
> obcs pkg, where the relaxation temperature is the linear  
> combination of model temperature and the prescribed temperature at  
> the boundary. This is not really what I want. If I need to write  
> some extra code to achieve my purpose (which is not uncommon),  
> could anyone provide any guidelines... or did I miss anything?
>
> btw, I did notice the 3-dim relaxation code emerged in the latest  
> checkpoint, but its relaxation timescale is set to be spatically  
> constant...
>
> Thanks, David
>
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