Assessment of the Daily Cloud-Free MODIS Snow-Cover Product for Monitoring the Snow-Cover Phenology over the Qinghai-Tibetan Plateau

Snow cover plays a crucial role in surface hydrology and energy balance, especially in the Qinghai-Tibetan Plateau (QTP). This study used 12 years (2000–2011) of ground-observed snow depth at 87 meteorological stations to assess and verify the accuracy of the daily cloud-free snow-cover product from the Moderate Resolution Imaging Spectroradiometer (MODIS) over the QTP. On average, the daily cloud-free MODIS snow-cover product correctly identified the occurrence of snow cover with an accuracy of 90.74%, ranging from 54.39% to 99.07% among the 87 sites. The MODIS-derived data have large uncertainties in identifying the snow-cover phenology on the threshold of FSC >0 and FSC >50% (FSC, fractional snow cover). However, the MODIS-derived data can capture the interannual variability of the snow-cover phenology as compared with in situ observations. This study highlights the uncertainties in the daily snow-free MODIS snow-cover product to reflect snow-cover phenology over the QTP.