Research on the Characteristics of Distribution and Variation of Snow Cover on the Tibetan Plateau by Using EOF Analysis

The snow depth data of SMMR (1978～1987) and daily snow depth data at 55 primary meteorological stations covering the period of 1963～1992 were used to analyse the spatial and temporal characteristics of snow cover over the Tibetan Plateau by using EOF method. The results show that the spatial distribution of snow cover over the Plateau is very inhomogeneous. It is found that heavy snow cover appears in the periphery, especially in the western and eastern parts of the plateau, while light snow cover appears in the vast interior of the plateau. The heavy snow cover region in the east of the plateau is also the region where the most significant interannual variation of snow cover occurs, and dominates the interannual variation of snow cover in the whole plateau. There is an opposite phase relation between the western parts and the eastern parts of the plateau in the interannual fluctuation of snow cover. There is an increasing trend of interannual fluctuation amplitude of snow cover over the plateau from the 1960s to the 1980s.