[MITgcm-support] silica fields in DIC package

[Hannah Kleppin]

Dear MITgcm users and developers,

since some time I have a slightly uneasy feeling every time I stumble across the variable silicaTEST in calcite_saturation.F (line 110) and the comment below "Cmick - TEMPORARY!!!!!". I finally decided to give it a closer look and 
I think the model only reads in surface silica fields (CALL  READ_REC_XY_RS  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=READ_REC_XY_RS>(DIC_silicaFile  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=DIC_silicaFile>,silica0  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=silica0>,intime0  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=intime0>,myIter  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=myIter>,myThid  <https://lxr.mitgcm.org/lxr2/ident/MITgcm?_i=myThid>), Line 101 in dic_fields_load.F), the silica values used for pH calculation at depth are in anyway fixed to 0.03 mol m^-3.
The dimensions of the silica input file in the verification example (https://github.com/MITgcm/MITgcm/tree/master/verification/tutorial_global_oce_biogeo) give the impression that a 3D silica field is used (it has dimensions Nx*Ny*Nr), eventhough if you look at the data, you can see that the lowest 3 levels are empty and the 12 levels above are always surface levels, thus its a silica surface monthly climatology.
For my own set-up I modified slightly some routines to read in 3d-fields of silica and use them in the calculation of the pH value. The resulting changes in, for example, the depth of the calcite saturation horizon are indeed small. For the tutorial example I cannot do this test since there are only the surface silica fields provided.
If you think its worth it I can upload the changes I did in github. But I'm not so familiar with the IO-routines and the exchanges for the overlap regions, so maybe someone would need to have a look on the changes I did. If someone has the deeper silica data of the tutorial example, then I could also run a test with them.

Cheers,
Hannah

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20211202/58aea131/attachment.html>