Satellite altimetry of large lakes of the Baltic Basin

Variability of the water level of largest lakes in the Baltic Basin is characterized by alternating periods of rise and drop according to the altimeteric measurements of TOPEX/Poseidon and Jason-1/2 satellites. Water level was calculated with the use of an algorithm of regional adaptive retracking for the Lakes Ilmen, Ladoga. Onega and Peipus. Applications of this algorithm considerably increase the amount of actual data records and significantly improve the accuracy of water level evaluation. According to the results, temporal variability of the Lake Ilmen, the Lake Ladoga and the Lake Piepus level is characterized by a wave with a period of 4-5 years and the Lake Onega level we found a wave with a period of 15 years. During the period from 1993 to 2011 lakes level was rising at a rate of 1.17±0.95 cm/yr for the Lakes Il`men´, 0.24±0.10 cm/yr - for the Lake Ladoga, 1.39±0.18 cm/yr - for the Lake Piepus and 0.18±0.09 cm/yr - for the Lake Onega.