[MITgcm-support] Salinity restoring and tracers

[Jean-Michel Campin]

Hi Christoph,

I have added the few pieces of code that should do the job.
>  option for ptracer to convert Salt Relax into additional EmP.
>   tested in exp. global_ocean.90x40x15.dwnslp (update output)
You can try it by updating your code and setting 
 PTRACERS_addSrelax2EmP=.TRUE.,
in data.ptracers (there is an example in
verification/global_ocean.90x40x15/input.dwnslp/data.ptracers)
Let me know if something does not work as expected.

Cheers,
Jean-Michel

On Wed, Sep 01, 2010 at 02:07:01PM -0400, Jean-Michel Campin wrote:
> Hi Christoph,
> 
> Yes, this is an issue that has been floating around for some time
> (see, e.g., the "ALLOW_OLD_VIRTUALFLUX" in pkg/dic/alk_surfforcing.F).
> We could add a flag in data.ptracers (off by default) that would
> do it. I can have something ready to test/check-in by the end of 
> the week.
> 
> Cheers,
> Jean-Michel
> 
> On Tue, Aug 31, 2010 at 10:43:27AM +0200, Christoph Voelker wrote:
> > Dear colleagues,
> >
> > when working with passive tracers in an ocean configuration of MITgcm  
> > one can define the concentration of the tracers in atmospheric water via  
> > the variable PTRACERS_EmPmR, such that evaporation, precipitation and  
> > runoff change the surface concentration of the tracers.
> > But if one does (additional) restoring of salinity, the implied  
> > freshwater flux does not enter the tracer balance in the surface model  
> > layers: the tracer balance (ptracers_forcing_surf.F) uses PmEpR, which  
> > does not contain the restoring term.
> > I think that there are good reasons to do so (i.e. it is a feature, not  
> > a bug); and if one uses only a weak salinity restoring to prevent model  
> > drift on top of freshwater fluxes from bulk formulae as I am doing  
> > normally this is not a big deal anyway.
> >
> > But I am now running a pretty extreme case with strong salinity  
> > restoring (to estimates of glacial SSS) and would like to include the  
> > implied freshwater fluxes into the tracer balances. Has anyone esle had  
> > this problem before and possibly solved/coded the terms in  
> > ptracers_forcing_surf.F? Are there further things one would have to  
> > consider?
> >
> > Cheers, Christoph
> > -- 
> > Dr. Christoph Voelker / Alfred-Wegener Institute for Polar and Marine  
> > Research
> > email: cvoelker at awi-bremerhaven.de / tel.#: ++49 471 4831 1848 /
> > mail: PO Box 120161, 27515 Bremerhaven, Germany
> >
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> 
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