Snow Cover Variation Analysis in Altay Area of Xinjiang

Based on meteorological data including monthly maximum snow depth,snow cover days and snowfall days,the beginning and ending snowfall date,and winter average temperature,the highest and the lowest temperature,precipitation (1961-2008) obtained from 7 weather stations in Altay region,the snow cover variation was analyzed using linear trend,Mann-kendall test and R/S analytical methods.The results indicated that winter mean temperature presented significantly increasing trend,especially for the minimum temperature,and precipitation also increased. Snowfall and snow cover occurred early in September or October and ended in next April or May in most areas of Altay. The yearly mean maximum snow depth and snow cover days presented a single peak variation,and the maximum snow cover depth was in Altay station,the minimum value is in Fuhai station,snow cover days was miniimum in Fuhai and maximum in Jimunai,while snowfall days decreased from west to east. The maximum snow depth increased obviously,and the variation of snow cover and snowfall days were not so obvious,but some difference existed in spatial distribution. The snow cover days and the snowfall days decreased obviously. The abrupt change test indicated that in regional mean,the maximum snow depth changed abruptly in about 1983,which was consistent with winter precipitation change. R/S analysis indicated that the maximum snow depth,snow cover days and snowfall days would be anti-persistence in future,and the anti-persistence characteristic of mean snowfall days,the maximum snow depth in Fuhai,snow cover days in Jimunai,snowfall days in Buerjin would be strongest relatively.