[MITgcm-support] solubility product of calcite and aragonite

[Hannah Kleppin]

Dear MITgcm users and developers,

I'm currently working on the DIC package in a regional ocean model set-up and I'm trying to extend the DIC package for our purposes.
I had some problems with the values of pCO2 and the flux of CO2. I then realized that in the calculation of the  stoichiometric solubility product of calcite and aragonite in the file dic_solvesaphe.F (line 844 and line 858) the natural logarithm of temperature is used (variable dlog_t_k, defined at line 440). I cannot access the reference paper (Mucci, 1983), but I think it should be Log10(t_k) (see e.g., the equic.m routine from Zeebe,Wolf-Gladrow athttps://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/CO2_System_in_Seawater/csys.html).
Using the log10 gives me at least realistic values of the stoichiometric solubility product of calcite, which showed before values of the order 10^224.

Furthermore I was wondering whether the units of omegaC (line 181 in calcite_saturation.F), thelocal saturation state with respect to calcite, are correct. Probably 
I'm mistaken, but to me it looks as if Ksp_TP_calc is in [mol 
kg^-1-SW]^2, calciumin [mol kg^-1-SW], whereas carbonate is converted back to [mol/m^3] (line 372 in dic_solvesaphe.F. This is maybe not the case if one uses the Follows formulation instead of the solvesaphe routines.).

Regards,
Hannah

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20210730/56ef3808/attachment.html>