Add new features for SNICAR-AD snow radiative transfer model

[daleihao]

This development adds new features for the SNICAR-AD snow albedo model to consider the non-spherical snow grain shape, internal mixing of dust-snow and solar-zenith-angle dependence of surface spectral irradiance under different atmospheric profiles. These features are turned off by default in our development. When using SNICAR_AD model by use_snicar_ad = .true.:

1. The snow grain shape can be selected by setting ‘snow_shape’ as: ‘sphere’, ‘spheroid’, ‘hexagonal_plate’, ‘koch_snowflake’.
2. The internal mixing of dust-snow can be turned on by use_dust_snow_internal_mixing = .false..
3. The atmospheric conditions can be selected by setting ‘snicar_atm_type’ as: ‘default’, ‘mid-latitude_winter’, ‘mid-latitude_summer’, ‘sub-Arctic_winter’, ‘sub-Arctic_summer’, ‘summit_Greenland’, ‘high_mountain’.

A test for this development is added.

[BFB]

[rljacob]

What does it mean to select "atmospheric conditions" when this is part of a global coupled run?

[rljacob]

Is this a feature need for v2 BGC runs?

[daleihao]

Is this a feature need for v2 BGC runs?

@bishtgautam What do you think?

[bishtgautam]

This feature isn't needed for BGC v2 sims. The model development was undertaken through one of the E3SM ecosystem projects.

[daleihao]

What does it mean to select "atmospheric conditions" when this is part of a global coupled run?

SNICAR-AD model calculates 5-band spectral albedo for snow, but the atmospheric model needs the surface albedo at just two bands (VIS and NIR) as I know. So the incoming surface spectral fluxes for 5 bands are needed to converse from 5-band to 2-band albedo. Here we provide the options for some typical different atmospheric conditions to describe the the incoming surface spectral fluxes for 5 bands. Current version just supports the same settings for the globe. In the future, we can improve both the land and atmospheric models to resolve this gap.

[daleihao]

We documented details of the development and evaluation of this new development in a manuscript, which is under review at GMD. The preprint of the manuscript can be found at: [https://gmd.copernicus.org/preprints/gmd-2022-67/].

[bishtgautam]

@daleihao After renaming the test, you also need to move: components/elm/cime_config/testdefs/testmods_dirs/elm/snicar_ad_improve/user_nl_elm to components/elm/cime_config/testdefs/testmods_dirs/elm/koch_snowflake/user_nl_elm.

[daleihao]

@daleihao After renaming the test, you also need to move: components/elm/cime_config/testdefs/testmods_dirs/elm/snicar_ad_improve/user_nl_elm to components/elm/cime_config/testdefs/testmods_dirs/elm/koch_snowflake/user_nl_elm.

Done. I have deleted the snicar_ad_improve folder.

[bishtgautam]

@peterdschwartz This PR looks ready to be merged. Can you please review this PR?

[peterdschwartz]

Apologies, I forgot to hit the "submit review" button last week and just noticed that it wasn't showing up here.

[daleihao]

Apologies, I forgot to hit the "submit review" button last week and just noticed that it wasn't showing up here.

No worry. Thanks for your help.

[peterdschwartz]

snicar_optics_5bnd_mam_c211006.nc appears to be missing from either of the data servers

[bishtgautam]

@peterdschwartz I have now uploaded the missing file on https://web.lcrc.anl.gov/public/e3sm/inputdata/lnd/clm2/snicardata/.

[peterdschwartz]

Merged to next

[rljacob]

@peterdschwartz when you copy-and-paste the PR description into the merge commit, remove all the markup. It creates unprintable characters in the log.

[peterdschwartz]

Merged to master. The new test snowflake test was one of the ones that didn't complete on mappy so I'll have to submit that bless request later