Spatio-Temporal Characteristics of the Snow Cover Ecllution in the Northern Region of Xinjiang over the Period of 1961 - 2008
1961年至2008年新疆北疆地区积雪的时空演变特征

Snow is an important water resource in Xinjiang. This paper focuses on the spatio-temporal evolution analysis of snow in the northern region of Xinjiang. With the daily snow depth data from 51 meteorological stations in the northern region of Xinjiang over the period of 1961-2008, we have mainly analyzed the spatial distribution and periodic characteristics of mean and annual maximum snow depth and the number of days with daily snowfall greater than 10 cm from November to March. The results show that: 1) The spatial distribution of the maximum snow depth and the number of days with daily snowfall greater than 10 cm show significant differences among different regions. In geography, heavy snow areas are mostly distributed along the mountain range, such as the area of north AleTai, FuYun and QingHe, Bogda-peak in medium Tianshan Mountain, Tacheng basin and Yili river valley in the west Tianshan Mountain; 2) The annual mean and annual maximum days with daily snowfall greater than 10 cm in heavy snow areas are 20-25 days and 65-75 days respectively; 3) Wavelet transform results show that the annual maximum snow depth in heavy snow areas has distinct periodic characteristics. In particular, there exists the first period of 7a and the second period of 11a in Aletai and Tacheng basin, which belong to the same warm area. The Yili river valley, which belongs to the cold front area, has vibration periods of 11 and 7 years or so; 4) The first and second periods in Tacheng basin are similar to those in Aletai region, but Yili river valley has the reverse periods. This is largely caused by climate background, circulation situation and the influence system. Also, it is somewhat related to geography position and the topography. At last, we get the maximum hit value range of snow depth through a comparative analysis of the northern snow-prone areas and the maximum spatial extent of snow depth in the study area during the last decade. All these analysis results will be collected in a database for building an early warning indicator system of snow in the Northern Region of Xinjiang.