How was snicar_optics_5bnd_snow_and_aerosols.nc generated?

[jentus]

Dear developers and users,

I am trying to understand the offline generation procedure of the 5-band SNICAR snow optics file used in Icepack:

snicar_optics_5bnd_snow_and_aerosols.nc

My understanding is that this file contains precomputed optical properties for snow and light-absorbing impurities / aerosols, which are then read by the SNICAR / delta-Eddington shortwave scheme during the model run. I have checked the Icepack source code and referred to Dang et al. and the SNICAR-AD description, but I am still not clear how this netCDF file was originally produced.

Could anyone help clarify the following points?

1. Which offline model, code, or workflow was used to generate this file?
2. Was it generated directly from SNICAR-AD / SNICARv3, or from a separate post-processing script?
3. For the pure snow part, what assumptions were used for the snow grain radius, snow grain shape, ice refractive index, wavelength grid, and spectral weighting?
4. For the aerosol / impurity part, were the optical properties taken from separate SNICAR aerosol files, such as black carbon or dust?

If there are any available scripts, documentation, or references describing this offline generation process, I would be very grateful.

Thank you very much!

 

[dbailey]

I believe these data were created using SNICAR by Mark Flanner originally in 2007. These were updated for CICE by Nicole Jeffery. Here are some references that might be helpful.

Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces

Abstract. Snow is an important climate regulator because it greatly increases the surface albedo of middle and high latitudes of the Earth. Earth system models (ESMs) often adopt two-stream approximations with different radiative transfer techniques, the same snow therefore has different solar...

tc.copernicus.org

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