INFERRING SURFACE VELOCITY OF SMALL GLACIERS USING SAR INTENSITY TRACKING METHOD

Abstract

Surface velocity is an important parameter that needs to be monitored to understand the glacier dynamics. The study focuses on four glaciers: Pensilungpa Glacier, Chhota Shigri Glacier, Milam Glacier, and South Lhonak Glacier. The main goal is to evaluate the surface velocity of these glaciers from 2019 to 2023. To achieve this, intensity tracking is used as the methodology, providing a detailed understanding of the dynamic changes within these glacier regions over the designated period. In this study, intensity tracking is utilized to find glacier surface velocity. The choice of intensity tracking over InSAR (Interferometric SAR) or DInSAR (Differential InSAR) approaches can be influenced by several factors, Coherence Issues i.e., InSAR and DInSAR techniques rely on the interference pattern between two SAR images, which can be affected by factors like decorrelation, topographic variations, and atmospheric conditions. The offset tracking method has been applied to the ground range detected (GRD) product obtained from Sentinel-1 satellite. This method is suitable for regions with higher glacier velocity where interferometry is generally affected by the loss of coherence. The offset tracking method works by tracking the features on the basis of another feature and calculates the offset between the two features in the images. Results indicate that between 2019 and 2023, the surface velocity of Pensilungpa Glacier ranges from 0.165 to 0.242 m/d, with uncertainties between 9.92% and 12.12%. For Chhota Shigri Glacier, velocities range from 0.14 to 0.181 m/d, with uncertainties between 7.73% and 13.75%. Milam Glacier shows fluctuating surface velocities from 0.198 to 0.224 m/d, with uncertainties ranging from 7.9% to 13.75%. South Lhonak Glacier exhibits daily velocities ranging from 0.164 to 0.185 m/d, with uncertainties between 8.6% and 12.9%.