snowpack spinup based on the 26 series runs

[adamrher]

Description of the run

Should we generate some CLM initial conditions with spun-up snowpack? This is a two-step process:

1. Run 20 year F or B case with hi-frequency coupler output for driving an I compset
2. Run CLM standalone, cycling over streams from the forcing run until the snowpack is spun-up (~500 years)

I am going to propose a B case 20 year forcing run, similar to 26d. That is, I am going to reset_snow / reset_snow_glc for the forcing run. The reason I advocate for resetting the snow in the forcing run, is I want to (if anything) bias the snow pack towards the warm side (favoring less snowpack and freshwater runoff to the LabSea). But I could be talked out of this.

In (1), we need to set namelist to setup the hi-freq coupled history for driving CLM standalone. I've done this with MCT in the past by setting these in user_nl_cpl

histaux_a2x3hr=.true.
histaux_a2x24hr=.true.
histaux_a2x1hr=.true.
histaux_a2x1hri=.true.

I am not sure whether this how you generate the forcing streams with NUOPC though. @mvertens @cecilehannay @JulioTBacmeister @gustavo-marques @fobryan3 @klindsay28 @billsacks @ekluzek @olyson

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[fobryan3]

I can't provide any guidance on the NUOPC question. I fully endorse the idea of having a more realistic and documented snow IC, but am curious why you advocate for a B-case rather than F-case to generate the forcing data for the I-case. That brings in drift in the atmos. lower boundary condition associated with ocean spinup itself. An alternative if you really want to go with B is to turn on salinity restoring in the ocean for this case to maintain Lab Sea convection.

[adamrher]

but am curious why you advocate for a B-case rather than F-case to generate the forcing data for the I-case. That brings in drift in the atmos.

Good point. An F-case may be more appropriate. But the F-cases always tend to be a-bit warmer (usually about +1 or +2 W/m2 RESTOM), and so don't approximate the B-cases well. I suppose it's a good question to ask whether the drift in the B-case is worse than the mean bias in an F-case. All I'll say is that a little drift in the forcing streams seems to be OK. Here's an example of an offline CLM spin-up, using F-case for the forcing streams, where the forcing is 20 years. There is drift from the "snow free" first year, and the snow covered year 20, of about 0.25K globally.

[gustavo-marques]

@adamrher: you can save CPL history files by setting XML variables HIST_N and HIST_OPTION.

[mvertens]

@adamrher - doing the type of spin up that you are suggesting is supported by NUOPC but is different that what you do with MCT. To duplicate the following MCT settings

histaux_a2x3hr=.true.
histaux_a2x24hr=.true.
histaux_a2x1hr=.true.
histaux_a2x1hri=.true.

If you look in nuopc.runconfig you will see a set of config variables that are histaux_atm2med_fileN_xxx You need to set the folloiwng in user_nl_cpl

   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.

This will turn on the following:

 histaux_atm2med_file1_auxname = atm.1h.inst
 histaux_atm2med_file1_doavg = .false.
 histaux_atm2med_file1_flds = Faxa_swndr:Faxa_swvdr:Faxa_swndf:Faxa_swvdf
 histaux_atm2med_file1_history_n = 1
 histaux_atm2med_file1_history_option = nhours
 histaux_atm2med_file1_ntperfile = 24

 histaux_atm2med_file2_auxname = atm.1h.avrg
 histaux_atm2med_file2_doavg = .true.
 histaux_atm2med_file2_flds = Sa_u:Sa_v
 histaux_atm2med_file2_history_n = 1
 histaux_atm2med_file2_history_option = nhours
 histaux_atm2med_file2_ntperfile = 24

 histaux_atm2med_file3_auxname = atm.3hprec.avrg
 histaux_atm2med_file3_doavg = .true.
 histaux_atm2med_file3_flds = Faxa_rainc:Faxa_rainl:Faxa_snowc:Faxa_snowl
 histaux_atm2med_file3_history_n = 3
 histaux_atm2med_file3_history_option = nhours
 histaux_atm2med_file3_ntperfile = 8

 histaux_atm2med_file4_auxname = atm.3h.avrg
 histaux_atm2med_file4_doavg = .true.
 histaux_atm2med_file4_flds = Sa_z:Sa_topo:Sa_u:Sa_v:Sa_tbot:Sa_ptem:Sa_shum:Sa_dens:Sa_pbot:Sa_pslv:Faxa_lwdn:Faxa_rainc:Faxa_rainl:Faxa_snowc:Faxa_snowl:Faxa_swndr:Faxa_swvdr:Faxa_swndf:Faxa_swvdf:Sa_co2diag:Sa_co2prog
 histaux_atm2med_file4_history_n = 3
 histaux_atm2med_file4_history_option = nhours
 histaux_atm2med_file4_ntperfile = 8

 histaux_atm2med_file5_auxname = atm.24h.avrg
 histaux_atm2med_file5_doavg = .true.
 histaux_atm2med_file5_flds = Faxa_bcph:Faxa_ocph:Faxa_dstwet:Faxa_dstdry:Sa_co2prog:Sa_co2diag
 histaux_atm2med_file5_history_n = 1
 histaux_atm2med_file5_history_option = ndays
 histaux_atm2med_file5_ntperfile = 1

With nuopc these are no longer hard-coded in the code but are run time options. I'm happy to talk about this tomorrow with @adamrher and @gustavo-marques and anyone else that is interested.

[adamrher]

I just spoke to Mariana. We need to debug the cpl history output option in nuopc over the next week before we can do the snowpack spinup. I will keep everyone posted.

[adamrher]

Quick update - we've resolved the issue of generating the streams w/ nuopc. We are meeting on wednesday to iron out setting those streams up for forcing clm standalone.