ASSESSMENT OF SENTINEL-1 PRODUCTS FOR REVEALING GLACIER SURFACE MOVEMENT IN INDIAN HIMALAYAS USING DIFFERENTIAL SAR INTERFEROMETRY

Recent studies have revealed that variations in glacier movement over larger time scales can be explained by the changes in total mass of the glacier, making it an effective indicator of glacier health. It is vital to obtain precise and accurate glacier movement velocity to investigate the glacier health. Satellite based Differential SAR (Synthetic Aperture Radar) Interferometry (DInSAR) techniques have been used for continuous monitoring of glacier surface movements. However, it is still challenging to employ this method in mountainous regions, such as the Indian Himalaya, due to e.g. severe temporal decorrelation and rapid glacier changes, and complex geological situation. Thanks to a pool of freely available ESA's Sentinel-1 C-Band SAR data with a short time repeat cycle, it is possible to overcome such challenges. This study attempts to assess the applicability of these datasets from its -1a and -1b platforms for estimating surface ice flow velocities in Indian Himalayan Region (IHR). Siachen Glacier, located in Karakoram range of IHR, is chosen as a representative glacier in this study, using which assessment of the dataset is performed and results are presented. 6-day interferometric pair was used for revealing the glacier velocity, estimated to range between 0m/y in some parts of the accumulation zone to 135m/y along the main trunk of the glacier in ablation zone. It is observed that, although datasets from Sentinel-1 mission are applicable for DInSAR processing in IHR, they provide a limited yet valuable opportunity to understand and model surface dynamics of mountain glaciers.