Abstract: Meteorological data at 17 weather stations in the Tianshan Mountains from 1959 to 2003 were analyzed to explore the variations in temperature and snow cover. The abrupt change test for snow depth was performed using Mann-Kendall statistic. The spatial distribution of maximum snow depth was calculated by employing GIDS interpolation and DEM data. The results show that mean temperature in winter had a rising trend at a rate of 0.44 ℃/10 a. The minimum temperature in winter increased more evidently at a rate of 0.79 ℃/10 a. The maximum snow depth has obviously deepened at a rate of 1.15 cm/10 a in the past 45 years, and it was about 16% higher than the average during 1991-2003. The Mann-Kendall statistic test of snow depth indicates that the abrupt change occurred in 1976. The maximum increment for snow cover depth occurred in Zhaoshu (Kunes) (39.3%) and Nilka (39.7%) in the west Tianshan Mountains. In contrast, the snow cover depth reduced by 17% in Barkol in the east Tianshan Mountains. There was a primary change periodicity of about 2.8 years in snow cover. In addition, snow cover days with a depth more than 10 cm increased distinctly, however, there was no obvious advance or delay in snow beginning and ending dates.

Key words: snow cover, Tianshan Mountains, climate change, North Atlantic Oscillation