基于MODIS数据的青藏高原积雪时空分布特征分析

An analysis of spatial-temporal distribution features of snow cover over the Tibetan Plateau based on MODIS data

利用2000―2014年间获取的MOD10A2积雪产品,结合数字高程模型数据,借助GIS空间分析方法,以积雪覆盖率(snow cover fraction,SCF)为指标,定量分析了青藏高原积雪的整体空间分布特征及高程、坡度和坡向等地形因素对高原积雪时空分布的影响。主要结论有:(1)青藏高原积雪覆盖具有高原周围和中部高大山脉积雪丰富、SCF高,内陆盆地和谷地积雪少、SCF低的特点;(2)海拔越高,SCF越高,积雪持续时间越长,年内变化越稳定;(3)海拔4 000 m以下年内积雪覆盖呈单峰型分布特点,海拔4 000 m以上则为双峰型;(4)SCF最低值在海拔6 000 m以下出现在夏季,而在海拔6 000 m以上则出现在冬季;(5)SCF在不同坡向中,北坡向最高,南坡向最低,东坡和西坡向居中。

In this paper, the spatial-temporal distribution of snow cover and the impact of topographic factors such as elevation, aspect and slope on snow cover distribution over the Tibetan Plateau were analyzed based on MOD10A2 acquired from 2000 to 2014 and the digital elevation model（DEM）using GIS spatial analysis techniques. The results are as follows： ① The snow cover over the Tibetan Plateau is characterized by rich snow and high snow cover fraction（SCF）in the surrounding areas and interior high mountains but less snow and low SCF in inland basins and valleys. ② Snow cover over the Tibetan Plateau exhibits the feature the higher the altitude, the higher the SCF, the longer the snow cover duration and the more stable the intra-annual variations. ③ Intra-annual snow cover distribution below 4 000 m is characterized by single-peak type, and that above 4 000 m is characterized by double-peak type. ④ The lowest SCF below 6 000 m occurs in summer while SCF above 6 000 m occurs in winter. ⑤ In different aspects, SCF is the highest in north aspect, the lowest in south aspect, and the middle between them in east and west aspects.