Mapping 1 km Fractional Snow Cover from Passive Microwave Brightness Temperature Data and MODIS Snow Cover Product over The Tibetan Plateau

Abstract: Snow is a critical component of the cryosphere, exhibiting substantial variations in both spatial and temporal dimensions. Accurately capturing the dynamic characteristics of seasonal snow cover is essential for predicting snowmelt runoff, monitoring hydrological cycle, and conducting climate change analysis. Optical satellite remote sensing has proven to be an effective tool for monitoring global and regional snow cover. However, existing fractional snow cover (FSC) data derived from optical imagery often encounters challenges, including large-scale spatial gaps caused by cloud cover and shadows. Meanwhile, passive microwave data, although valuable, typically possess lower spatial resolution, rendering them inadequate for detecting snow cover dynamics under complex surface conditions. In this study, we employed a fractional snow cover fusion estimation method to generate high-resolution (1 km) spatiotemporally continuous FSC estimation datasets for the Tibetan Plateau region from the years 2008 to 2021, regardless of weather conditions. The accuracy of the FSC data was systematically evaluated over the study period, demonstrating excellent consistency with independent datasets, including Landsat-derived FSC (total 20 scenes; RMSE = 0.092–0.193; R = 0.83–0.946) and ground-based snow observations (Approximately 70,000 site records; Overall Accuracy = 0.95; Kappa = 0.95). Furthermore, the FSC datasets produced by this method exhibits superior performance in accurately capturing the complex daily snow cover dynamics compared to other FSC datasets(Overall Accuracy: 0.95 vs. 0.91 vs. 0.85). In conclusion, the daily FSC maps of the Tibetan Plateau generated from 2008 to 2021 using data fusion methods in this study offer high accuracy and complete spatiotemporal coverage. These FSC datasets hold substantial value for climate projections, hydrological studies, and water management at both global and regional scales.

Fig.1 Spatial Distribution of Snow Cover (1 km) for daily FSC data over the Tibetan Plateau from 2008 to 2021. The dates are shown at the bottom of the subplots. The blank areas denote missing values due to various reasons. The range of snow cover variation is from 0 to 1, where 0 indicates no snow cover and 1 indicates full snow cover.

Table.1 Summary of accuracy metrics for the 1km daily fractional snow cover data over the Tibetan Plateau using 10 Landsat scenes FSC data as the reference data.