[MITgcm-support] bug in DIC package

Christoph Voelker Christoph.Voelker at awi.de
Thu Feb 19 05:48:48 EST 2009


Hi,

I think I have found a small bug in dic_surfforcing_init.F (using last 
weeks cvs checkout of MITgcm). The bug only matters when you do not set 
DIC_BIOTIC (which I did inadvertently), so it is probably unimportant in 
most cases. Anyway, it shouldn't be there, so here is my description

The following lines in dic_surfforcing_init.F set the initial 
concentrations of alkalinity and phosphate for calculating the initial 
discribution of CO@ partial pressure. if DIC_BIOTIC is not set, 
alkalinity is set proportional to salinity.

#ifdef DIC_BIOTIC
              surfalk(i,j) = PTRACER(i,j,klev,bi,bj,2)
      &                          * maskC(i,j,kLev,bi,bj)
              surfphos(i,j)= PTRACER(i,j,klev,bi,bj,3)
      &                          * maskC(i,j,kLev,bi,bj)
#else
              surfalk(i,j) = 2.366595 _d 0 * salt(i,j,kLev,bi,bj)/gsm_s
      &                          * maskC(i,j,kLev,bi,bj)
              surfphos(i,j)= 5.1225 _d -4 * maskC(i,j,kLev,bi,bj)
#endif

However, at this point the global mean salinity gsm_s is not yet 
defined, so the calculation produces infinity. I think this has to do 
with the order in which the initializations for the different packages 
are done.

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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