[MITgcm-support] Salinity restoring and tracers

[Jean-Michel Campin]

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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