ИСТИНА

The article presents the results of ice cover identificationand the investigation of interannual ice regimevariability of the Rybinsk Reservoir based on the satellitealtimetry and radiometry data. For this purpose, thestudy analyzed the joint distribution of the radiobrightness temperature of the underlying surface,measured by two channels (18.7 and 34.0 GHz) with anon-board microwave radiometer, and thebackscattering coefficient at the Ku frequencycalculated by the altimeter. The analysis of the joint distribution of these parameters identified two areas ofthe cluster that corresponded to pure water and ice accumulation. The study was carried out using thetopological filtering algorithm DPS (Discrete PerfectSets) and subsequent isolation of the most massive 3-D concentrations. The results of the research showed that this approachallows us to identify with adequate accuracy the icecover in the water area of the Rybinsk Reservoir.According to Jason-1 and Jason-2 satellite data, from 2002 to 2016, the time for the start of freezing shifted ata rate of 0.624±0.152 days per year, and the openingtime amounted to 0.673±0.256 days per year. Theduration of the ice regime for this time intervaldecreased at a rate of -1.303±0.341 days per year. Themaximum duration of freezing was observed in thewinter of 2002/2003 and amounted to 164 days, and theminimum - in the winter of 2006/2007 and was 134 days.