In this paper we assess the snow cover and its dynamics for the western river basins of the Indus River system and their subbasins located in Afghanistan, China, India and Pakistan for the period 2001-2012. First, we validate the Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow products from Terra and Aqua against the Landsat Thematic Mapper/Enhanced Thematic Mapper plus data set, and then improve them for clouds by applying a validated non spectral cloud removal technique. The improved snow product has been analysed on a seasonal and annual basis against different topographic parameters (aspect, elevation and slope). Our results show a decreasing tendency for the annual average snow cover for the westerlies influenced basins (upper Indus basin, Astore, Hunza, Shigar and Shyok) and an increasing tendency for the monsoon influenced basins (Jhelum, Kabul, Swat and Gilgit). Seasonal average snow cover decreases during winter and autumn, and increases during spring and summer, which is consistent with the observed cooling and warming trends during the respective seasons. Subbasins at relatively higher latitudes/altitudes show higher variability than basins at lower latitudes/middle altitudes. Northeastern and northwestern aspects feature greater snow cover. The mean end of summer regional snow line altitude (SLA) zones range from 3000 to 5000 m asl for all basins. Our analysis provides an indication of a descending end of summer regional SLA zone for most of the studied basins, which is significant for the Shyok and Kabul basins, thus indicating a change in their water resources. Such results are consistent with the observed hydroclimatic data, recently collected local perceptions and glacier mass balances for the investigated period within the UIB. Moreover, our analysis shows a significant correlation

翻译：在本文中,我们评估了2001-2012年期间印度河系统及其位于阿富汗、中国、印度和巴基斯坦的亚流域西部河流流域的雪层覆盖及其动态。首先,我们验证了Terra和Aqua的中分辨率成像分光计(MODIS)每日雪产品来自Terra和Aqua的来自Landsat主题地图/增强的Umapper/加强主题地图加数据集的雪层产品,然后通过应用经验证的非光谱云清除技术,改进了云层的雪层覆盖。根据不同的地形参数(地貌、海拔和斜坡)对改进的雪产产品进行了季节性和年度分析。我们的结果显示,湿度、海拔、海拔、海拔、海拔和坡地表的年平均雪层平均覆盖呈下降趋势。在相对较高的海拔地区,从相对较高的海拔、北海拔、海拔和北海拔海拔的海拔地区测算表明,海拔和北海拔的海拔地区平均海拔的海流数据显示。