Spatiotemporal variation of snow cover over the Tibetan Plateau based on MODIS snow product, 2001-2014

In this paper, we investigate the spatiotemporal characteristics and trends of snow cover fraction (SCF) in the Tibetan Plateau (TP) and seven upstream river basins (Yellow, Yangtze, Mekong, Salween, Brahmaputra, Indus and Yarkant) by employing the Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2001-2014. The possible linkage between the SCF, and temperature and precipitation changes over the TP and individual basins is also investigated. Results suggest that the distribution of snow cover over the TP exhibit a large spatiotemporal heterogeneity with high SCFs mainly concentrating on the southern and western edges which is strongly linked to the moist air supplies. The distribution of snow cover is highly dependent on the elevations, with a higher SCF and a later onset of snow melt at the higher elevation zones than at the lowers. There is an elevation threshold existing for separating two distinct snow cover regimes, which are 4000m for the western basins and 5000m for the southeastern basins. The snow cover over the TP has slightly decreased by about 1.1% during 2001-2014, with dramatic reductions mostly lying in the heavy snowy regions and some light increases occurring in the areas with annual mean SCFs mostly less than 10%. The reduction rates of snow cover increase with the rising of altitudes for the TP average, and the basins of Indus, Yarkant, Salween and Brahmaputra. At the same time, the Yellow and Yangtze basins exhibit larger increasing rates of snow cover at the higher elevations zones. The SCF variations are linked to the temperature and precipitation changes. Precipitation tends to be the major factor impacting the snow cover changes in the TP during 2001-2014.