[MITgcm-support] Salinity restoring and tracers

Christoph Voelker christoph.voelker at awi.de
Tue Aug 31 04:43:27 EDT 2010

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 

Cheers, Christoph
Dr. Christoph Voelker / Alfred-Wegener Institute for Polar and Marine 
email: cvoelker at awi-bremerhaven.de / tel.#: ++49 471 4831 1848 /
mail: PO Box 120161, 27515 Bremerhaven, Germany

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