Introduce slab ocean aquaplanet compsets for cam7

[brian-eaton]

What is the feature/what would you like to discuss?

PR #1203 adds compsets QPLT and QPMT for aquaplanet with prescribed SSTs for cam7 LT and MT configurations. That resolved part of issue #814. This issue is to introduce slab ocean aquaplanet compsets for cam7 LT and MT (QSLT and QSMT?).

Is there anyone in particular you want to be part of this conversation?

@brianpm

Will this change (regression test) answers?

No

Will you be implementing this enhancement yourself?

Any CAM SE can do this

[brianpm]

In addition to matching the slab-ocean configuration we had in CESM2, there's a request to support an aquaplanet with thermodynamic sea-ice turned on from Nicole Feldl (@nfeldl). They have a configuration set up that was used in: https://iopscience.iop.org/article/10.1088/2752-5295/ad9b45.

I'm not sure whether that should be a separate compset or just an option in QSLT/QSMT. Nicole and Mark England have offered to provide their solution if it is useful. Let me know and I can get in touch with them.

[nfeldl]

Thank you for considering this request. I am including below the steps we took to implement the thermodynamic sea ice in the CESM2-CAM6 aquaplanet. In our testing, we found the stability of the sea ice to be sensitive to the q-flux (we generated our own file) and the R_snw parameter. I look forward to your suggestions for the best way to make this configuration available to other users.

--

Here is a description on how to run the CESM2 aquaplanet simulation with thermodynamic sea ice, and a reasonable seasonal cycle:
A few changes were made to the source code before building the case.
Firstly, in ~/cesm2/cime/src/drivers/mct/shr/seq_infodata_mod.F90 I commented out the following to include a seasonal cycle.

if ( infodata%aqua_planet ) then
	infodata%aqua_planet_sst = 1
	! infodata%perpetual = .true.
	! infodata%perpetual_ymd = aqua_perpetual_ymd
endif

Secondly, in ~/cesm2/components/cice/src/source/ice_domain_size.F90 I changed the following lines to equals 1 so that the thermodynamic sea ice k_therm=0 could be run

nilyr     = 1
nslyr     = 1

I then setup a case with the following compset 1850_CAM60_SLND_CICE_DOCN%SOM_SROF_SGLC_SWAV
The following lines were added to user_nl_cice. The choice of r_snw = 0.70 was set here, with ice dynamics turned off.

kdyn = 0
kitd = 1
prescribed_ice = .false.
tr_aero =  .true.
tr_fy =  .true.
tr_iage =  .true.
grid_file = '~/domain/domain.aqua.fv1.9x2.5.nc'
kmt_file = '~/domain/domain.aqua.fv1.9x2.5.nc'
grid_type = 'latlon'
grid_format = 'nc'
kstrength = 0
ice_ic = 'default'
ktherm = 0
r_snw = 0.7

A symmetrised file for the ozone and aerosols files were created and imposed in user_nl_cam (more details can be given if needed here but it might be just easier to include the files and user_nl_cam because it is pretty extensive changes).
In addition in user_nl_cam:

use_topo_file = .false.
micro_mg_num_steps = 8

The following changes were made which determine the depth of the mixed layer and the climatological Q-flux input

./xmlchange LND_DOMAIN_PATH=/home/maenglan/domain/
./xmlchange LND_DOMAIN_FILE=domain.aqua.fv1.9x2.5.nc
./xmlchange DOCN_MODE=som
./xmlchange DOCN_SOM_FILENAME=som.forcing.aquaplanet.Qfluxcontrol1850annualNHSH_h30_sstQOBS.2degFV.nc

The following lines were added to the user_nl_cpl which gives reasonable orbital parameter values

orb_eccen = 0.
orb_obliq = 23.45
orb_mvelp = 0.
orb_mode  = 'fixed_parameters'

In L314 of env_build.xml the following change from prognostic to thermo_only were made (not sure if totally necessary)
<entry id="CICE_MODE" value="thermo_only">
The following line was added to the user_nl_docn file
domainfile = '~/domain/domain.aqua.fv1.9x2.5.nc'
After that the case was built, and submitted as normal.