ICCS Deliverable 1

[jwallwork23]

Enable GEOS-Chem diagnostics to be archived while GISS-GC runs.

Background

GISS Model E has monthly diagnostics and sub-daily diagnostics (SUBDD). Both use an intermediate file representation, which is not ideal. However, the monthly diagnostics are generally thought to be implemented in a better way. SUBDDs can be either instantaneous (i) or averaged - these are indicated in the rundeck.

Diagnostics requested of GEOS-Chem are set in a HISTORY.rc file. If diagnostics are requested then a customised derived type variable is created holding only the requested diagnostics (in interests of time and memory efficiency).

The key thing is species concentrations. The next priority diagnostics for FETCH4 are the production/loss "prodloss" and reaction rate "rxnrate" diagnostics. (Production/loss and reaction rates are key because they are used for training emulators and because they are rarely well-supported in other chemistry climate models. GEOS-Chem can archive any reaction rate or any family of reaction rates, whereas most codes only implement a handful of reactions.)

Existing code

Lee implemented a way to take GEOS-Chem concentrations and port them into the SUBDD (sub-daily diagnostics) code in GISS model E so they can be archived the way model E outputs them. However, this was done at version 12.9.3 of GEOS-Chem so it's possible that these need updating now that we're at version 14.3.1.

[jwallwork23]

Further notes:

The bulk of the coupling work is done in CHEM_DRV.F90, based on the GCHP approach. CHEM_DRV.F90 loops over everything except tracer transport, which is handled by the GCM. CHEM_DRV.F90 contains various examples that we should extend.

So far we've only been running with -cold-restart. If we drop this then the model will restart from a checkpoint file. GEOS-Chem outputs in checkpoint files are crucial for the project.