ALE crash without thermodynamics

[angus-g]

If you run with ALE set to regrid (onto say, the z* coordinate), but with ENABLE_THERMODYNAMICS = False, a few crashes occur where it is assumed that temperature and salinity are accessible as a consequence of having ALE enabled:

• remapping T/S
• creating a group pass
• pressure reconstruction

[adcroft]

Thanks @angus-g. This is a case of options colliding with each other. I will put conditionals around the three code points you listed to avoid segv's.

Running in general coordinates without temperature/salinity is ill-defined - not using T/S really only makes sense for the stacked shallow equation mode in which layer density is prescribed and time-invariant. In any other mode (whether diabatic or not) the density is determined by an equation of state. Bob had a "buoyancy" mode in HIM and GOLD that was basically a single constituent fluid which we haven't thought about providing in general coordinates. Is that what you were looking for?

Notes for my own sake:

• ADIABATIC turns off the parameterizations.
• ENABLE_THERMODYNAMICS becomes ...%use_temperature and dictates whether the "tv" (thermodynamic variables) structure is allocated. Turning off tv is really only meaningful in stacked shallow water mode.
• Using parameterizations without T/S is already tested for
• Need to add warning for combination of general coordinates and non-T/S mode, until we provide a buoyancy mode in g.c.