Estimation of Snow Water Equivalent Using Sentinel SAR Data in the Indian Himalaya

In this study, a methodology to retrieve Snow Water Equivalent (SWE) information for shallow snow coverage is proposed, something where traditional methods fail, as they require more snow depth to function properly. The proposed algorithm uses the thermal resistance of snowpack to retrieve the SWE by linearly relating the thermal resistance to the backscattering ratios of winter and autumn (snow-free) images acquired with C-band SAR (Sentinel-lA). The SWE (absolute value) is then estimated from the thermal resistance. The results are verified using field data collected at Dhundi observatory maintained by the Snow and Avalanche Study Establishment (SASE), located in the Himalaya (Himachal Pradesh, India; 32°21'N and 77°07’). One winter and two autumn images were used to check the feasibility of the algorithm. The RMSE of SWE estimated using the retrieval algorithm is 3 cm for Pair-l (30 Jan 2016 and 02 Oct 2015), and 2.8 cm for Pair-2 (30 Jan 2016 and 20 Oct 2016).

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