Regional OHT offset

[alicebarthel]

The analysis member mpas_ocn_meridional_heat_transport.F includes the capability of computing regional OHT. Given the regional masks (e.g. 'Atlantic_MOC' starts at 32S), we need to add the heat transport at 32S, just like we do with the MOC integration.

[xylar]

@milenaveneziani, is this something you have done already in a branch somewhere? I vaguely remember discussing this at some point.

[milenaveneziani]

No, I think I raised this as an issue/bug in the old MPAS-O repo. The current regional calculation is actually wrong as it starts from a 0 heat transport at 32S, instead of actually calculating it as we do with the volume transport for the MOC am.