[MITgcm-support] Forcing theta within gchem

[Roland Young]

Hi,

I was wondering at what point in the code a tracer that forces the theta field should apply its forcing? I have various tracers which I want to force the theta field via latent heat exchanges. I calculate the relevant phase changes as a subroutine to gchem_forcing_sep, and at present I calculate the latent heat exchange there too. However if I try to apply the forcing to theta there (simply as theta = theta + dtheta, with appropriate looping), the total tracer mass rapidly increases (10% over a day). I’m pretty sure I’m updating theta in the wrong place, or doing it incorrectly. 

I could calculate the latent heat forcing in one timestep and apply it in the next in external_forcing_t - is that valid or are the tracers advected before that? Is there a way to update the prognostic fields within the gchem interface? I can’t find any examples that do it (the only one I can find updates CFC concentrations, but these don’t seem to force the model temperatures).

Thanks,

Roland