Change of Characteristic Index of Daily Snowfall in Winter in Altay Prefecture,Xinjiang

After analyzing the data of daily snowfall at 7 observation stations in Altay Prefecture,Xinjiang in winter during the period of 1961- 2011,in this paper the linear trend method,Cubic function,Morlet wavelet transform and R / S analysis were used to study climate change in the study area. The results are as follows: There was a significant positive correlation between winter snowfall and daily snowfall at the Altay and other stations,and also an obvious decadal change of daily snowfall and winter snowfall. Snowfall was in a linear increase trend in long term,in which the frequency and contribution rate of slight snowfall were the highest,and the frequency of slight snowfall was about 20 times of heavy snowfall. The effects of heavy snowfall on winter snowfall was significant at all the observation stations. Cubic function fitting revealed that slight snowfall frequency and its contribution rate were decreased from the 1990s,but the occurring frequency and contribution rate of heavy snowfall was in an increase trend. Morlet wavelet analysis revealed that there were the decadal and annual changes of daily snowfall. R / S analysis revealed that the daily snowfall in the study area will in a gradual decrease trend in the future,especially the snowfall frequency and its contribution rate.