Abstract:Snow cover over the Qinghai-Tibet Plateau (QTP) is a key element of Asian Water Tower. It is also an important indicator of weather and climate change. Its spatio-temporal changes can influence the regional climate and ecosystem. In this study, the spatiotemporal distribution and trends of snow cover were analyzed based on remote sensing data, and its hydrological and climate effects were also explored. The results show the followings:(1) Snow cover was dominantly distributed in mountainous areas, and the largest snow depth and Snow Cover Days (SCD) were found in the Dangla and Nianqing Dangla Mountains, with the average SCD of over 120 days, and annual average snow depth of over 10 cm; whilst there was few snow cover in the plain area and Qaidam Basin, e.g. ephemeral snow cover, with average SCD of less than 15 day and annual snow depth of less than 1 cm. (2) Snow cover days and depth were decreased in the period of 1980-2018, especially after the year of 2000. (3) There was large radiative forcing in the mountainous areas with deep snow and large SCD, and the maximum value beyond 15 W m^-2; thus, the snow cover over QTP plays important feedbacks to the climate system. (4) The QTP is the source of runoff in headwater regions of many rivers, and snow melt water contributed to the soil moisture and river runoff in spring. (5) The frequency of snow disaster was increased by extreme weather events, and early warning system and protective measures should be enhanced to minimize the loss caused by snow disaster.