Surface UV retrieval from satellite data

Irradiance of biologically effective ultraviolet radiation on the Earth's surface is retrieved from satellite measurements using radiative transfer models. Retrieval methods are reviewed with a special emphasis on questions pertinent to the Arctic environment. In general, the main problem is the high variability of cloudiness. The most prominent features of high latitudes are the low Sun and the high UV reflectivity of snow-covered terrain. Being white like clouds, snow is a challenge for satellite imagery. The dependence of UV albedo on the properties of snow and ambient conditions is discussed. The use of auxiliary snow cover data from a meteorological model is planned.