New approach for the global mapping of fractional snow coverage in boreal forest and tundra belt applicable to various sensors

A feasible method for estimating the areal fraction of snow cover for boreal forest and tundra belt from optical data is presented. The method SCAmod by the Finnish Environment Institute is based on a semi-empirical model where fractional snow cover is expressed as a function of at-satellite observed reflectance. The apparent forest transmissivity and reflectance of three major contributors (wet snow, forest canopy and snow-free ground) serve as model parameters. The forest transmissivity describes the visibility of the ground through forest canopy from above, and was previously determined from MODIS reflectance data with a great effort. Here we present a new method for transmissivity generation using global land cover map. Validation of gained FSC estimates as well as of NASA MOD10_L2 fractional snow product against Finnish ground truth data is presented.