Single point snow albedo mods

[wwieder]

Description:

See comments on the SNICAR PR re. changes we can consider for snow albedo modification. Once we make a plan forward I'll create new issues in this repo.

Given the possible directions forward, it seems the best plan to investigate snow albedo modifications may be a series of shorter duration runs to assess arctic survival, timing of snowmelt and albedo in AD simulations. I'm also going to do these for single point cases to start with.

The three sites are:

• Dikson --lat 73.5 --lon 80.5 , 91% Arctic C3 Grass
• Agapa -- lat 71.15 --lon 87.5 , 65% shrub, 34% grass control case seems to survive
• Pyasina --lat 73.5 --lon 87.5 , 60% shrub, 38% grass

Case	modification	notes
control_01	default BGC	ctsm5.1.dev152
control_sp	default SP	ctsm5.1.dev152
Sturm	snow_thermal_cond_method = 'Sturm1997'	Sturm, not Jordan
sno_age	xdrdt = 2	ctsm51_params.c211112_snowAge.nc
snow_ABC	xdrdt = 2, scvng_fct_mlt_sf = 0.5, snw_rds_refrz = 1500	ctsm51_params.c211112_snowAge_scvgn_rds.nc
blk_c	snicar_snobc_intmix = .true.	xmlchange CLM_BLDNML_OPTS -ignore_warnings & removed namelist from error flag in controlMod.F90
blk_ABC	snicar_snobc_intmix = .true. + ABC from above	as above + ctsm51_params.c211112_snowAge_scvgn_rds.nc
blk_ABCD	fresh_snw_rds_max = 400._r8 (previously 203) + blk_ABC above	as above + AerosolMod.F90
Sturm_blk_ABCD	snow_thermal_cond_method = 'Sturm1997' + blk_ABCD above	as above + Sturm
Sturm_blk_ABCD2	xdrdt = 4, scvng_fct_mlt_sf = 0.25	results nearly same as above
Sturm_blk_ABCD3	xdrdt = 10, scvng_fct_mlt_sf = 0.10	results nearly same as above

---

Final changes inlucded
user_nl_clm changes

snow_thermal_cond_method = 'Sturm1997'
snicar_snobc_intmix = .true.
paramfile = '/glade/scratch/wwieder/deadArctic/ctsm51_params.c211112_snowAge_scvgn_rds.nc'

• Default parameter: xdrdt = 1, scvng_fct_mlt_sf = 1, snw_rds_refrz = 1000
• Parameter changes inlcude: xdrdt = 2, scvng_fct_mlt_sf = 0.5, snw_rds_refrz = 1500
• snicar_snowbc required:
  • xmlchange CLM_BLDNML_OPTS -ignore_warnings &
  • removed namelist from error flag in /glade/u/home/wwieder/CTSM/src/main/controlMod.F90

-fresh_snw_rds_max = 400._r8 as SourceMods (e.g., /glade/scratch/wwieder/deadArctic/Pyasina/Sturm_blk_ABCD/SourceMods/src.clmAerosolMod.F90)

---

Diagnostics:
Diags (if available)

---

Run directories and Output:
Output (if still available):
/glade/scratch/wwieder/deadArctic/

---

Contacts:
@wwieder

[wwieder]

Control case at Agapa (shrub point) seems to be dying:

(*note x-axes are not the same to show longer time series of LAI decline with snow ~ 0.8 m in June.)

Similarly, at Dickson (grass point)

[olyson]

Fyi, it looks like you can change fresh_snw_rds_max in the lnd namelist, at least in ctsm5.1.dev150.

[wwieder]

4x and 10x changes in xdrdt and scvng_fct_mlt_sf from default parameter have little change over the 2x modifications we already tried in Sturm_blk_ABCD. Should we be reducing the 'fresh snow' albedos simulated in advance of melt?