[MITgcm-devel] possible problem with sigmaR and shelfice

[Martin Losch]

Hi there,

I have stumble across a potential problem with sigmaR. It's computed as maskC(k)*(sig(k)-sig(k-1)) in grad_sigma.F or zero for k=1. For ice shelves we can have k>0 and sigmaR does not make sense at the interface between ice and ocean, but usually that should not be problematic, but for example in gmredi_calc_tensor, sigmaR is vertically averaged to give dSigmaDr at the cell centers, and here the wrong sigmaR is used (and then implicitly for slope computations, etc.)
In the same way calc_ivdc.F will compute the wrong IVDConvCount at the interface.

I am not sure if this really causes problems, but I suggest to compute sigmaR like this maskC(k)*maskC(k-1)*(sig(k)-sig(k-1)) instead, and likewise modify calc_ivdc (and use sigmar in that routine as suggested by the comment in do_ocean_phys.F?). What do you think?

I do not see any effects on testreport (but there are effects with ice shelves and ivdc_kappa>0).

Martin