中文摘要：

基于1961-2006年全疆32个测雪站的逐日积雪深度资料,分析了北疆区域积雪开始和结束时间的气候分布和时间变化特征.结果表明：积雪开始和结束时间存在明显的区域差异,这种差异主要是由地形高度变化引起的.积雪开始时间以12a和6a左右的周期振荡为主,积雪结束时间则以5a和8a左右的周期振荡为主.在不同海拔,积雪开始时间均呈偏晚趋势,积雪结束时间在较低海拔地区（≤1000m）呈偏晚趋势,而在较高海拔地区（1001～2000m）呈偏早趋势.积雪开始时间相对结束时间的趋势变化更为显著.积雪开始和结束时间和海拔关系密切,积雪开始时间随海拔升高而提前,积雪结束时间则随海拔升高而推迟.

英文摘要：

Based on daily snow depth data from 32 stations in Xinjiang Region from 1961 to 2006,the climate characteristics of starting date and ending date of snow cover and their temporal variation in northern Xinjiang Region are analyzed. The results show that the starting date and ending date of snow cover have obvious regional difference,which is mainly caused by the terrain height change. The oscillations with 12 a and 8 a periods are the main temporal characteristics of starting date of snow cover,while the oscillations with 5 a and 8 a periods are the main temporal characteristics of ending date of snow cover. Snow cover starts earlier with altitude increasing,and snow cover ends later with altitude increasing in lower altitude （≤1 000 m）,but in higher altitude （1 001~2 000 m）,it is opposite. The variation of starting date is more significant than that of the ending date. By correlation and composite analyses,it is found that the starting date and ending date of snow cover have a positive relation with altitude. With altitude ascending,the starting date becomes earlier,and the ending date later.