Abstract. The paper presents a theoretical analysis of seasonal brightness temperature
variations at a number of large freshwater lakes: Baikal, Ladoga, Great
Bear Lake (GBL), Great Slave Lake (GSL), and Huron, retrieved from
Microwave Imaging Radiometer with Aperture Synthesis (MIRAS) data (1.4 GHz)
of the Soil Moisture and Ocean Salinity (SMOS) satellite. The analysis was
performed using the model of microwave radiation of plane layered
heterogeneous nonisothermal medium. The input parameters for the model were
real regional climatological characteristics and glaciological parameters of
ice cover of the study lakes. Three distinct seasonal brightness temperature
time regions corresponding to different phenological phases of the lake
surfaces: complete ice cover, ice melt and deterioration, and open water
were revealed. The paper demonstrates the possibility to determine the
beginning of ice cover deterioration from satellite microwave radiometry
data. The obtained results can be useful for setting the operating terms of
winter crossings and roads on ice, as with the beginning of ice
deterioration, these transportation routes across water bodies (rivers,
lakes, water reservoirs) become insecure and cannot be used any more.