December 2021: Comprehensive documentation published:

• A paper (Flanner et al., 2021) describing details and evaluation of the v3 model release is published in Geoscientific Model Development, available at: https://doi.org/10.5194/gmd-14-7673-2021.

May 2021 update:

• Colorado dust optical properties revised, based on a new inversion of imaginary refractive indices that optimize comparison against the dust spectral albedo measurements of Skiles et al. (2017). The updated dust is more absorptive, though still less absorptive than the other three types of dust.

New features included in the January 2021 release:

• Replacement of the tri-diagonal matrix two-stream solver with the Adding-Doubling solver (Dang et al., 2019)
• Incorporation of surface spectral irradiances that depend on solar zenith angle
• Updated optical properties of light-absorbing constituents

New features included in the June 2020 release:

• Snow algae (Cook et al., 2017)
• Non-spherical ice particles (He et al., 2017)
• Carbon dioxide ice (Hansen, 2005; Singh et al., 2016)
• More options for H₂O ice refractive indices: (a) Warren (1984) / Perovich and Govoni (1991); (b) Warren and Brandt (2008); (c) Picard et al. (2016) / Warren and Brandt (2008)
• More options for dust optical properties: (a) Saharan dust (Balkanski et al., 2007); (b) San Juan Mountains, Colorado (Skiles et al., 2017); (c) Greenland (Polashenski et al., 2015); (d) Martian dust (Wolff et al., 2009,2010; Singh et al., 2016)
• Strongly-absorbing brown carbon (Kirchstetter et al., 2004)
• New volcanic ash properties (Flanner et al., 2014)
• A larger size bin (5-50μm radius) for dust and ash particles
• Additional options for surface spectral irradiance weighting: (a) Mid-latitude winter; (b) Mid-latitude summer; (c) Sub-Arctic winter; (d) Sub-Arctic summer; (e) Summit Greenland; (f) High Mountain (surface pressure of 556 hPa); (g) Top of atmosphere; and minor bug fixes to previously-used spectral irradiance profiles.

References (cited above):

Balkanski, Y., M. Schulz, T. Claquin, and S. Guibert (2007), Reevaluation of mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7 (1), 81-95, doi:10.5194/acp-7-81-2007.

Cook, J. M., Hodson, A. J., Gardner, A. S., Flanner, M., Tedstone, A. J., Williamson, C., Irvine-Fynn, T. D. L., Nilsson, J., Bryant, R., and Tranter, M. (2017), Quantifying bioalbedo: a new physically based model and discussion of empirical methods for characterising biological influence on ice and snow albedo, The Cryosphere, 11, 2611-2632, doi: 10.5194/tc-11-2611-2017.

Dang, C., Zender, C. S., and Flanner, M. G. (2019), Intercomparison and improvement of two-stream shortwave radiative transfer schemes in Earth system models for a unified treatment of cryospheric surfaces, The Cryosphere, 13, 2325-2343, doi:10.5194/tc-13-2325-2019.

Flanner, M. G., Arnheim, J. B., Cook, J. M., Dang, C., He, C., Huang, X., Singh, D., Skiles, S. M., Whicker, C. A., and Zender, C. S. (2021), SNICAR-ADv3: a community tool for modeling spectral snow albedo, Geosci. Model Dev., 14, 7673-7704, https://doi.org/10.5194/gmd-14-7673-2021.

Flanner, M. G., A. S. Gardner, S. Eckhardt, A. Stohl, J. Perket (2014), Aerosol radiative forcing from the 2010 Eyjafjallajökull volcanic eruptions, J. Geophys. Res. Atmos., 119, 9481-9491, doi:10.1002/2014JD021977.

Flanner, M. G., C. S. Zender, J. T. Randerson, and P. J. Rasch (2007), Present day climate forcing and response from black carbon in snow, J. Geophys. Res., 112, D11202, doi:10.1029/2006JD008003.

Hansen, G. B. (2005), Ultraviolet to near-infrared absorption spectrum of carbon dioxide ice from 0.174 to 1.8 um, J. Geophys. Res., 110, E11003, doi:10.1029/2005JE002531.

He, C., Y. Takano, K.-N. Liou, et al. (2017), Impact of snow grain shape and black carbon-snow internal mixing on snow optical properties: Parameterizations for climate models, J. Climate, 30(24), 10019-10036, doi:10.1175/JCLI-D-17-0300.1.

Kirchstetter, T. W., T. Novakov, and P. V. Hobbs (2004), Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon, J. Geophys. Res., 109, D21208, doi:10.1029/2004JD004999.

Picard, G., Libois, Q., and Arnaud, L. (2016), Refinement of the ice absorption spectrum in the visible using radiance profile measurements in Antarctic snow, The Cryosphere, 10, 2655-2672, doi:10.5194/tc-10-2655-2016.

Polashenski, C. M., J. E. Dibb, M. G. Flanner, J. Y. Chen, Z. R. Courville, A. M. Lai, J. J. Schauer, M. M. Shafer, and M. Bergin (2015), Neither dust nor black carbon causing apparent albedo decline in Greenland's dry snow zone: Implications for MODIS C5 surface reflectance, Geophys. Res. Lett., 42, 9319-9327, doi:10.1002/2015GL065912.

Singh, D., and M. G. Flanner (2016), An improved carbon dioxide snow spectral albedo model: Application to Martian conditions, J. Geophys. Res. Planets, 121, 2037-2054, doi:10.1002/2016JE005040.

Skiles, S. M., Painter, T., and Okin, G. (2017), A method to retrieve the spectral complex refractive index and single scattering optical properties of dust deposited in mountain snow, Journal of Glaciology. Vol. 63, 133-147, doi:10.1017/jog.2016.126.

Toon, O. B., C. P. McKay, T. P. Ackerman, and K. Santhanam (1989), Rapid calculation of radiative heating rates and photodissociation rates in inhomogeneous multiple scattering atmospheres, J. Geophys. Res., 94 (D13), 16,287-16,301.

Warren, S. G. (1984), Optical constants of ice from the ultraviolet to the microwave, Appl. Opt., 23, 1206-1225.

Warren, S. G., and R. E. Brandt (2008), Optical constants of ice from the ultraviolet to the microwave: A revised compilation, J. Geophys. Res., 113, D14220, doi:10.1029/2007JD009744.

Wolff, M. J., M. D. Smith, R. T. Clancy, R. Arvidson, M. Kahre, F. Seelos IV, S. Murchie, and H. Savijarvi (2009), Wavelength dependence of dust aerosol single scattering albedo as observed by the Compact Reconnaissance Imaging Spectrometer, J. Geophys. Res., 114, E00D04, doi:10.1029/2009JE003350.

Wolff, M. J., R. T. Clancy, J. D. Goguen, M. C. Malin, and B. A. Cantor (2010), Ultraviolet dust aerosol properties as observed by MARCI, Icarus, 208(1), 143-155.