基于MODIS雪盖数据的叶尔羌河流域积雪再分析

高原高寒干旱山区积雪融水是大多数河流的重要补给源,对当地社会经济发展、生态环境等起着举足轻重的作用。以叶尔羌河流域为对象,基于2001-2016年的MOD10A2积雪产品,采用GIS空间分析提取叶尔羌河山区的积雪面积,应用线性趋势分析法,分析不同高程带积雪面积年内及年际变化规律。结果表明：1）流域积雪面积年内变化表现为“积累-消减-积累-消融”的二次过程,春秋季以积累为主,夏季以消融为主,冬季因为风吹雪迁移及升华,积雪面积表现为消减现象;2）以200 m间隔划分流域高程带,1-2月积雪覆盖率随高程呈现一致的平缓上升和下降规律。3、4、11、12月在A区（<3 600 m）呈现微弱上升趋势,B区和C区（3 600～6 000 m）呈现显著上升趋势,D区（>6 000 m）呈现下降趋势。5～10月积雪覆盖率在A区处于消融状态,B区（3 600～4 800 m）积雪覆盖率呈现平缓上升趋势;C区（4 800～6 000 m）积雪覆盖率上升趋势显著,D区积雪覆盖率呈现下降趋势;3）A、B区积雪覆盖率年内变化呈现单峰曲线,积雪的主要补给期在秋、冬季。C、D区积雪覆盖率年内变化曲线呈现“M”型,积雪覆盖率为“积累-消减-积累-消融” 的二次过程,冬季因为风吹雪迁移至低海拔山区或升华造成积雪消减,D区因为海拔高,夏季积雪覆盖率为80%左右;4）积雪面积年际变化呈现下降趋势,秋、冬季下降趋势最为明显;5）低海拔区（A、B、C区）内积雪覆盖率年际变化呈现微弱下降趋势;高海拔区（D区）内积雪覆盖率年际变化不大,呈现微弱的上升趋势。

Analysis of Snow Coverage in Yarkant River Basin Based on MODIS Snow Data

The snow-melt water is one of the most important supply sources of most rivers in the mountain area of arid area, which plays an important role on the local social and economic development, ecological environment, et al. Based on GIS spatial analysis method, the snow coverage was extracted from MOD10A2 spanning from 2001 to 2016 in the mountain region of Yarkant River basin. The annual and inter-annual variations of snow coverage in the different elevation zones were analyzed by using linear trend analysis method. The results show that:1) Accumulation-reduction-accumulation-ablation process was presented in the annual change of the snow coverage. In spring and autumn, the snow accumulated, and it melted in summer. In winter, the snow coverage area was reduced due to the snow migration and sublimation by wind blowing. 2) With elevation interval of 200 m, the snow coverage rate in January and February showed a consistently gentle rise and fall with elevation. In March, April, November and December, it showed the same change trend. In the zone A (<3 600 m), the snow coverage rate showed gentle rise trend with the elevation. In the zone B (3 600~4 800 m) and zone C (4 800~6 000 m), significant rise trend was shown. In the zone D (>6 000 m), it showed a downward trend. From May to October, snow was totally in the melting state in the zone A, and in the gentle rise trend in the zone B and significantly rise trend in the zone C, while decreased trend in the zone D. 3) The annual variations of snow coverage rate in the zone A and zone B showed a unimodal curve, and the main replenishment period was in autumn and winter. In the zone C and zone D, the curve showed "M" type. The accumulation-reduction-accumulation-ablation process was presented, and the snow coverage area was reduced due to the migration to low attitude region and the sublimation by wind blowing in winter. The snow coverage rate was about 80% in the zone D due to the high altitude. 4) The inter-annual variation of snow cover showed a decreasing trend, especially in autumn and winter. 5) The inter-annual variation of the snow area showed a decreasing trend in low altitude areas (zone A, B and C), while it showed a weak increasing trend in high altitude (zone D).