Reconcile Units With Calculations in gas_chem.hpp about mam4xx HOT 3 OPEN

It might be worth considering variable names that have units, e.g., rx_rates_per_cc_per_s, washout_rates_per_s.

from mam4xx.

Just to follow up on this some -- I went through the Fortran version of the code more carefully (specifically subroutine gas_phase_chemdr, variable reaction_rates), tracking down the origin of the relevant equations. I found the following: 1) at least all of the chemical reaction elements of this array seem to have the same units with each other at any given time; 2) however, the units of all these elements do change multiple times over the coarse of this subroutine. Specifically, they start off (after the call to setrxt) as cm^3 / (molecule -- s) (i.e., like a reaction rate constant for a second-order reaction), but after the call to adjrxt they become s^{-1}; then during the call to rate_diags_calc they become molecules / (cm^3 - s).

from mam4xx.

Thank you for looking into this, Brian! That certainly provides some peace of mind.

And, based on this, it appears that the arrays carrying quantities and rates likely contain entries with heterogeneous units. As such, this should be looked into after porting is complete/validated and we can modify/improve the code.

edit: follow-up thoughts

from mam4xx.