关键词: 积雪增量, 积雪日数, 趋势

Abstract:

This paper studies the spatial and temporal distribution of snow cover in China in recent 50 years by using the snow cover depth，snow cover days and days of temperature steadily below 0 ℃ from 1 400 observation stations in China． The analysis results show that the spatial distribution of snow cover was inhomogeneous，which mainly distributed in the north of Xinjiang，the northeast China and the Tibetan Plateau． The increment of annual snow cover exceeded 50 cm in these three areas，and snow cover days exceeded 100d in the north of Xinjiang and the northeast China． From 1991 to 2000 the snow cover increment was less in most areas of China． The Mann － Kendall test and moving T － test were used to check the abrupt change in this paper． The increment of snow cover presented evidently increasing trend in the north of Xinjiang and the northeast China，and the abrupt change occurred in 1984 and 1978，respectively，but for Tibetan Plateau，the snow cover increased before 1985 and then decreased，the abrupt change occurred in 2002． In north and central China，there were no significant decadal variation for snow cover． The days of temperature steadily below 0 ℃ were obviously decreasing in all areas． In a word，the temperature was increasing，snow cover days changed evidently and the snow cover increment was increasing in the north of Xinjiang and the northeast China，which reflected the frequency of strong snowfall was increasing in these areas． And the temperature was increasing，snow cover days changed little，the snow cover increment was decreasing in northChina plain，which reflected the frequency of strong snowfall was decreasing there．

Key words:  snow cover increment, snow cover days, Mann － Kendall test, T － test