关键词: 雪灾, 西藏高原, 空间分布, 大气环流

Abstract:

With daily snow cover data collected at 38 meteorological stations in the Tibetan Plateau from October through next April during 1960-2008, we analyzed the spatial distribution of three degrees of snow disasters, classified according to snow depth and snow covering days, in pre-winter, winter and spring. Result showed that there were 3 high-frequency centers of the snow disaster: the middle Himalayas area centered in Nielamu, the eastern Naqu area centered in Jiali and the eastern Himalayas area centered in Cuona. The snow disaster mainly occurred in pre-winter and winter with different frequency distribution. The moderate snow disaster and severe snow disaster mainly occurred in the middle Himalayas area, Ali area and Naqu. A synthesis analysis with NCEP/NCAR monthly mean height field reanalysis data in regional snow anomaly years and no snow years showed that the 500 hPa atmospheric circulation at high-latitude in the Northern Hemisphere appeared similar in pre-winter and winter with significant "+-+-" wave train from the Atlantic eastward coast to the western Pacific, and there was a "-+-+-+" wave train from western Europe in the spring. The Long-wave trough and ridge in the European mainland enhanced significantly and the longitude circulation developed in the 3 period. The Eurasia height anomaly fields in pre-winter and winter appeared higher in the west and lower in the east, and in spring showed on the contrary. The intensity and position of the Polar vortex, the Ural mountain high pressure ridge, the Baikal Lake high pressure ridge and North American trough have significant that differences between snow disaster years and non-snow disaster years. The East Asian trough didnt show significant differences except in spring.

Key words: snow disaster, Tibetan Plateau, spatial distribution, atmospheric circulation