Document, test, and add testing for running CPLHIST cases in NUOPC starting from a B case

[ekluzek]

We need to document the process, as well as test the process, and preferably adding ongoing testing to ensure the process works to run a B case save CPLHIST output and use it to run an I case for CTSM.

We have old MCT data that we use to do the process here, and we test it with the cplhist test mod in CTSM.

/glade/campaign/cesm/cesmdata/inputdata/atm/datm7/atm_forcing.cdeps_datm.CPLHIST_cam6ctsm51_cesm23a12c_ne30pg3g17_1850

So that goes back to ctsm5.1 in cesm2_3_alpha12c

The old MCT documentation for this for clm5_0 is here:

https://escomp.github.io/CTSM/release-clm5.0/users_guide/running-special-cases/Running-with-your-own-previous-simulation-as-atmospheric-forcing-to-spinup-the-model.html#running-with-atmospheric-forcing-from-a-previous-simulation

This started from a discussion in TSS Software.

Definition of done:

• Figure out the process
• Test it by hand to make sure it works
• Bring in cdeps version that handles ndep for CPLHIT (Create new auxiliary history file for cplhist test with ndep data  #1844)
• Have the process documented somewhere (update the User's Guide?) (could be a README file, or on the Wiki to get a start at it as well...)
• Add a test for creating the files needed in CMEPS
• Decide on what other testing should be done
• Add other testing needed
• Update cdeps with final data (Update cdeps with updated CPLHIST data #3759)

[olyson]

My understanding is that the following needs to be set in user_nl_cpl to generate cplhist files in a B (or F) case:

histaux_atm2med_file1_enabled = .true.
histaux_atm2med_file2_enabled = .true.
histaux_atm2med_file3_enabled = .true.
histaux_atm2med_file4_enabled = .true.
histaux_atm2med_file5_enabled = .true.

[ekluzek]

In meeting today, @samsrabin strongly recommends doing documentation directly in the User's Guide for this. We'd like to have the testing in place so we know it's solid when it's needed for coupled simulations this Fall so November 15th deadline.