The starting and ending dates of snow cover and their characteristics were analyzed by using daily data of the 16 observational stations in the Tianshan Mountains from 1981 to 1996 in the paper.It was showed that snow cover gradually started later and ended earlier from west to east and from north to south in the study area due to different altitude and precipitation.The snow cover started from late September in the high-altitude regions and ended in May and even June in the north of Tianshan Mountains while it started later and end in February with very short duration in the south of Tianshan Mountains.The annual variation in snow cover starting and ending dates at the stations was obvious,and the change trend was that the starting date became later and the snow duration became shorter.With increasing altitude,snow cover started earlier and ended later.The higher altitude,the earlier the starting date of snow cover and the later the ending date.The latitude also impacted the starting and ending date rather than longitude.Due to different sunshine and precipitation,with increasing altitude of 100m,the starting dates advanced 2.18 days and 3.69 days in the north and south slopes respectively,and the ending dates delayed 3.25 days and 3.18 days respectively.%利用1981—1996年新疆天山地区16个气象台站的积雪观测资料,研究天山典型区积雪初始、终止日期的时空分布特征及影响因素。研究结果表明,受水热状况及复杂地形影响,研究区内自西向东,自北向南积雪初始日期逐渐推后,终止日期逐渐提前。9月末,天山海拔较高的地区开始积雪,11月上旬至12月上旬积雪迅速发展;天山中部和北部的积雪会持续到3月下旬,而海拔较高的台站则会持续到5月,甚至6月;天山南坡初日较晚,2月积雪就会终止。天山地区的积雪初始和终止日期年际波动较大,并呈现出积雪初日越来越晚,积雪期逐年缩短的趋势。随着海拔升高,气象台站积雪初日逐渐提前,积雪终日逐渐推后,形成倒三角形状,对积雪初始、终止日期和经、纬度的分析表明,其主要受纬度影响。天山南、北坡水热条件不一致,高度每上升100 m,天山北坡积雪初日提前2.18 d,终日推迟3.25 d;天山南坡积雪初日提前3.69 d,终日推迟3.18 d。
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