[MITgcm-support] solubility product of calcite and aragonite

[Jonathan Lauderdale]

Dear Hannah,

Thanks for spotting these - I think you are correct on both counts. Do you want to submit an issue on GitHub and then either you or I can follow it up with a pull request with corrections?

Thanks,

Jonathan
___________________________________________________________________________
Dr. Jonathan M. Lauderdale
Research Scientist
Department of Earth, Atmosphere and Planetary Sciences 
Massachusetts Institute of Technology 
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> On Jul 30, 2021, at 7:52 AM, Hannah Kleppin <hkleppin at marum.de> wrote:
> 
> 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 at https://www.soest.hawaii.edu/oceanography/faculty/zeebe_files/CO2_System_in_Seawater/csys.html <https://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), the local 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, calcium in [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 
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