Ice cover determination of the Volga and the Don River reservoirs on the base of Jason-2 sattelite observations

This work aims to development of a simple method for distinction between open water and ice cover on the base of geophysical data record (GDR) of altimetry satellite Jason-2 for large and middle-sized freshwater inland water bodies. The method is applied for six reservoirs at the Volga and Don Rivers. It was shown earlier [1, 2] that the retracking of the Jason-1, 2 satellite data allow us to determine with sufficient accuracy the water level variations either for the large Rybinsk reservoir, or for the middle-sized Volga reservoirs (the Gorky reservoir and others). Ice and snow conditions of inland waters are of interest since they influence the life and economic activity of people and are significant indicators of climate changes. Satellite methods of ice-snow cover observations have certain advantages, connected with the global coverage, instantaneous observations of large water areas and relatively low cost. However, the use of satellite methods for inland waters is often limited by their spatial resolution comparable to or greater than the size of water reservoirs. Satellites carrying instruments of high spatial resolution often have large repeat periods (ICESat), either the data quality strongly depend on weather conditions (Landsat). In this regard, the use of Jason -1, 2 satellites, equipped with a dual-frequency (13.6 GHz and 5 GHz) radar altimeters and three-channel (18, 21 and 37 GHz) microwave radiometers is of great interest, because the footprint diameter of their altimeters in Ku-band is about 10 Km and the repeat period of observations is ten days, that make them suitable for observations of large and medium-sized inland waters.