New option for climatological rescaling of precipitation

[gmao-rreichle]

Adds commented-out placeholder for new PRECIP_FILE_CLIMSCALE rc variable introduced by GEOS-ESM/GEOSgcm_GridComp#1484

[mathomp4]

@gmao-rreichle There is a whole bunch of comments above that about picking the right PRECIP_FILE. Do you know if any of that is even still accurate?

I ask only because @sshakoor1 and myself were a bit confused by the precip correction stuff when he was working on his linkbcs.py script (see #823). In his bcs_catalog.yaml for this he has:

precip_correction:
  r21c: /discover/nobackup/projects/gmao/share/gmao_ops/fvInput/merra_land/precip_CPCUexcludeAfrica-CMAP_corrected_MERRA/GEOSdas-2_1_4
  merra-2: /discover/nobackup/projects/gmao/share/gmao_ops/fvInput/merra_land/precip_CPCUexcludeAfrica-CMAP_corrected_MERRA/GEOSdas-2_1_4
  ops: /gpfsm/dnb51/projects/p15/iau/merra_land/precip_CPCU-CMAP_corrected_MERRA/GEOSdas-2_1_4

Which I think was sort of trying to make sense of the comments in AGCM.rc.tmpl.

After looking at #823 with @sshakoor1 it looks like in the control yaml currently precip_correction: is either true or false. If true we link ExtData/PCP to the merra-2 entry of the catalog.

But, since you are here maybe the right question is: What should we have in bcs_catalog.tmpl going forward? Do we need perhaps a "string" option like:

precip_correction: # none, scale, non-scaled

and then those link in a different directory to ExtData/PCP? Or do both your new scale and old...non-scaled (🤷🏼) use the same path?

We just want to make sure when this gets to @rtodling at some point, he can have the right link in ExtData/PCP.

Also, I guess, what paths would you recommend for the precip_correction in the catalog. I mean, maybe only one (the merra-2) is even worth having? And perhaps r21c is just all wrong?

[gmao-rreichle]

@mathomp4 :

There is a whole bunch of comments above that about picking the right PRECIP_FILE. Do you know if any of that is even still accurate?

The products and paths are certainly out of date. I'm not sure this is the best place to document the specific precipitation corrections or scaling file paths and file names associated with a given product. But then again, I never run replays, or even the GCM, so don't take my word for it.

In any case, I updated the documentation in the hope of shedding a bit more light on what the PRECIP_FILE* config variables do.

I'm not qualified to document exactly how the config files need to look to make this work. I'm blissfully ignorant of gcm_setup and fvsetup.

The precipitation corrections and scaling for M21C is fully encoded in the GEOSadas tag: https://github.com/GEOS-ESM/GEOSadas/releases/tag/GEOSadas-5.30.3-M21C-7, but again, don't ask me how this works in detail...

Feel free to add documentation into AGCM.rc.tmpl with details on how to link files specific for a given replay config.

I'll add a couple of comments on #823 in an attempt to address the rest of your questions.

[mathomp4]

@gmao-rreichle So when @sshakoor1 and I looked at the Ops scripts to find where MERRA2 and M21C were pointing to to for ExtData/PCP it turns out that the script:

e5303_m21c_jan18/run/lnbcs

currently points to:

/discover/nobackup/projects/gmao/share/dao_ops/fvInput/precip_correction

and in AGCM.rc.tmpl they use:

PRECIP_FILE: ExtData/PCP/precip_corr_R21C/diag/Y%y4/M%m2/R21C.tavg_1hr_prcpcorr_c360_sfc.%y4%m2%d2_%h230.nc4
#PRECIP_FILE_CLIMSCALE: ExtData/PCP/precip_corr_R21C/diag/clim/M21CtoIMGv7BF.precip_clim_scale.8888%m2%d2.nc4

I'm wondering if your comment should use these paths/templates? For consistency?

It looks like precip_corr_R21C/diag/ is a sort of "meta" directory where some years point to one set of data and other years to others

[gmao-rreichle]

Thanks, @mathomp4 ! I revised the comments in AGCM.rc.tmpl accordingly (aa022bd)