GCHP mass flux moisture correction

yuanjianz commented 6 days ago

Your name

Yuanjian Zhang

Your affiliation

WashU

What happened? What did you expect to happen?

https://github.com/geoschem/GCHP/blob/e499969f3831261e1fd15774b9fc68d01d012ba2/src/GCHP_GridComp/GCHPctmEnv_GridComp/GCHPctmEnv_GridCompMod.F90#L873-L885

Humidity is positive so 1-SPHU is smaller than 1, so dryMF = MF/(1-SPHU) is bigger than MF, which does not make sense to me. Shouldn't mass flux from GMAO archives be multiplied instead of being divided by 1-SPHU?

What are the steps to reproduce the bug?

Run a mass flux simulation with dry pressure advection.

Please attach any relevant configuration and log files.

No response

What GCHP version were you using?

14.4.0

What environment were you running GCHP on?

Local cluster

What compiler and version were you using?

gcc 10.2.0

What MPI library and version were you using?

OpenMPI 4.0.5

Will you be addressing this bug yourself?

Yes

Additional information

No response

lizziel commented 6 days ago

This makes sense to me. 1/(1-sphu) is the same as kg total / kg dry, but it would make sense to convert by instead multiplying by kg dry/kg total. When you change it do you see improvements in comparisons with wind runs?

yuanjianz commented 23 hours ago

Theoretically, this bug fix is reasonable and a trivial change. But the test reminds me of the previous comparison between mass flux and wind. With / without this fix, the advection in mass flux is much less vigorous than in wind. Together with my recent massflux v.s. wind fullchem benchmark showing unreasonble surface aerosol concentration, I think it is necessary to continue the investigation in #342 with help from @sdeastham .

lizziel commented 6 hours ago

Using mass fluxes in GCHP is still experimental, even with this update. Do you want this to be merged or wait until more testing is done?

geoschem / GCHP