Recent advances in microwave radiometry of snow on lake ice

Methods for retrieval of the water equivalent of snow on terrain are mostly based on using space-borne Ku and Ka band microwave radiometer data [1]. Retrieval is only possible when snow cover is dry. In northern lake-rich regions the effect of lakes and, additionally, other land-use categories to the brightness temperature leads to the mixed-pixel problem: the observed brightness temperature includes contributions from forested areas, open areas, frozen lakes, etc. within the antenna beam. Hence, the brightness temperature behavior as a function of snow characteristics has to be known at all used frequencies and separately for each land-use category. The best way to determine these behaviors is to conduct measurements with an airborne multi-frequency radiometer under various snow and weather conditions. The spatial resolution of space-borne radiometers at Ku and Ka band is so modest that detailed information for each land-use category cannot in practice be obtained from space-borne radiometers.