Modeling effective albedo as a function of land cover type and snow type
The Center for Environmental Radioactivity (CERAD) project ”UV- maps” aims to obtain geographically distributed time-series of solar ultraviolet (UV) radiation in Norway. Since UV-measurements are limited to a few monitoring stations, a full representation of the spatial and temporal distribution needs to be based on a ra-diative transfer model (RTM). A key parameter is the regional albedo distribution. The albedo model developed here apply a gridded set of local albedo values to derive theregional, effective albedo at any given point. In Norway there is a UV-monitoring network that has been operating since 1996, delivering almost continual 20-years time series of UV data. We use these stations as our modelling reference points. In our albedo model we use land cover information and snow dispersion data for 11 years. Land cover classifications combined with snow classifications constitute a matrix of albedo values, with one albedo value for each combination of land cover type and snow type, under the hypothesis that the snow albedo is affected by the underlying land type. In this paper, we outline how to determine these albedo parameters by regression analysis, and give examples of calculated albedo values for some combinations of land cover and snow type.