[MITgcm-support] Running the DIC and CFC under the GCHEM

[Christoph Voelker]

Dear Tobia,

yes, at present, the two packages can't run together, although there is
no fundamental reason for that. The practical reason - at least that's
what I believe - is that they both use the same infrastructure (e.g.
global tracer fields or surface flux fields) defined by the ptracer and
gchem packages. It is no problem to make them co-exist, but then one
needs to account for which tracer / surface flux is which (i.e. to have
pointer offests so that e.g. tracers one to five correspond to the
tracers defined in the dic package and tracers 6 ff to the CFC tracers..
And that means introducing a number of additional #ifdefs into the code.

Actually, I wonder that you got the model to run with the two packages
activated: In gchem_check.F there are the lines:
C     GCHEM cannot (yet!) run cfc and dic together
      IF ( useDIC .AND. useCFC ) THEN
         WRITE(msgBuf,'(A)') 'useDIC and useCFC cannot both be .TRUE.'
         CALL PRINT_ERROR( msgBuf , myThid )
         STOP 'ABNORMAL END: S/R GCHEM_CHECK'
      ENDIF
Did you switch that off?

At present I see three options for you:
You could create a combined package for yourself, by inserting the CFC
variables into the DIC code; this is probably more or less easy, since
the CFC variables have no sources or sinks in the interior of the ocean
You could try to make the two packages compatible, by inserting enough
case distinctions with ifdefs to take into account that the tracers
share room in the same tracer array.
Or you waste computer time and run the physical model once with the DIC
package and once with the CFC package. Since neither of the two packages
interferes with each other or with the physical circulation, that should
be equivalent two running them together, but at the cost of running the
physics twice..

Cheers, christoph

On 6/9/15 12:57 PM, Tudino, Tobia wrote:
> Dear all, 
>
> I am trying to run a MITgcm setting that includes both the
> biogeochemistry and the CFCs. The former is fine, but, for some
> reasons I cannot have the CFCs outputs.
> Following web recommendations, I have added the “cfc” to the
> package.conf and created a link with the CFCs input. However, they
> don’t appear in the final results.
> Further online researches suggest that I cannot run online both the
> DIC and the CFC packages under the GCHEM.
> Does anyone confirm this last step? Is there any chance to run the
> model online with both the CFCs and the biogeochemistry? Additional
> documentations?
>
> Thanks for the help.
>
> Tobia 
>  
> Tobia Tudino
> tt282 at exeter.ac.uk <mailto:tt282 at exeter.ac.uk>
> PhD Student
> Geography
> College of Life and Environmental Science
> Skype: tobia.tudino
>
>
>
>
>
> _______________________________________________
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> MITgcm-support at mitgcm.org
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-- 
Christoph Voelker
Alfred Wegener Institute for Polar and Marine Research
Am Handelshafen 12
27570 Bremerhaven, Germany
e: Christoph.Voelker at awi.de
t: +49 471 4831 1848

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