Temperature comparison between MPAS-Ocean and Omega

[cbegeman]

MPAS-Ocean temperature is given as potential temperature whereas Omega (with nonlinear EOS) temperature is given as conservative temperature. Somewhere we need to convert one of these.

Should this be located in IOStep's write/read model dataset? This would mean that the remapped initial condition file would likely be given in potential temperature (and thus usable by both MPAS-O and Omega) and then Omega would do the conversion from potential to conservative temperature when writing its output files.

[xylar]

I hadn't thought about this. Presumably the same applies to converting between practical salinity and absolute salinity.

I would think that map_from_native_model_vars and map_from_native_model_vars should take care of these as part of renaming variables. This would be clean because presumably the names on the Omega side (or at least the metadata) could also be made to reflect the conversion. Since open_model_dataset() and write_model_dataset() call these methods, conversion would take place during read/write as well.

(I would probably avoid calling this activity "remapping" because in my mind that term is reserved for interpolation from one grid or mesh to another, but that's beside the point.)

[cbegeman]

map_from_native_model_vars sounds good.

(I would probably avoid calling this activity "remapping" because in my mind that term is reserved for interpolation from one grid or mesh to another, but that's beside the point.)

I was just bringing up remapping because presumably we want to do that once per mesh, not once for Omega in CT and once for MPAS-O in PT. I think putting it in map_from_native_model_vars achieves this.

Presumably the same applies to converting between practical salinity and absolute salinity.

Yes, for ICs, comparison with reanalysis and obs, and publishing output, we'd have to convert from SA to PS. We could think about bypassing the conversion from PS to SA (and perhaps PT/CT as well) for some idealized test cases where it wouldn't make a difference.