Estimation of fractional snow cover based on FY-2E/VISSR over the Tibetan Plateau

Abstract

Snow cover plays an important role in hydrological processes, surface radiation and global climate change research, especially in Tibetan Plateau. Most of current fractional snow cover products are mainly determined from polar-orbit satellites sensors, such as Advanced Very High Resolution Radiometer (AVHRR) and (Moderate Resolution Imaging Spectroradiometer (MODIS). MODIS snow cover is generated using 8-day composition data in order to reduce the problem caused by cloud obscuration. However, snow cover mapping is often required to obtain at the temporal scale of less than one day, especially in the case of disasters. Geostationary satellites show potential to retrieve fractional snow cover with lower cloud obscuration in daily scale. In this paper, we propose a technique to estimate fractional snow cover over the Tibetan Plateau by Chinese geostationary satellite Fengyun-2E (FY-2E) in two winters of 2011 and 2012. Normalized Difference Snow Index (NDSI), Ratio Snow Index (RSI) and Difference Snow Index (DSI) based on 0.6μm and 3.9μm channel of Visible and Infrared Spin Scan Radiometer (VISSR) onboard FY-2E are used to estimate fractional snow cover. Landsat ETM+ data is treated as true value of fractional snow cover to develop the models based on VISSR snow indexes. When validated by ETM+ fractional snow cover, the model based on VISSR DSI with exponential curve fitting show the best performance in estimating fractional snow cover, with R-square of 0.62 and RMSE of 0.17.