Bio-SNICAR CookJoseph 2017 BioSNICAR refers to coupled bio-optical and radiative transfer models which, together, predict the spectral albedo of a volume of ice or snow. The physical properties of the snow, irradiance conditions and impurities can be defined by the user. The bio-optical scheme is a mixing model that takes user-defined concentrations of various algal pigments to determine the imaginary part of the refractive index for algal cells. This information is then used to determine the optical properties of the cells using Mie theory, given information about the cell size. The optical properties of the cells are then added to a lookup library that can be accessed by an adapted form of the radiative transfer model ‘SNICAR’ (Flanner et al., 2007). BioSNICAR refers to coupled bio-optical and radiative transfer models which, together, predict the spectral albedo of a volume of ice or snow. The physical properties of the snow, irradiance conditions and impurities can be defined by the user. The bio-optical scheme is a mixing model that takes user-defined concentrations of various algal pigments to determine the imaginary part of the refractive index for algal cells. This information is then used to determine the optical properties of the cells using Mie theory, given information about the cell size. The optical properties of the cells are then added to a lookup library that can be accessed by an adapted form of the radiative transfer model ‘SNICAR’ (Flanner et al., 2007).