Repeat pass imaging-based velocity estimation of Siachen glacier in J&K Himalaya using Sentinel-2 and Landsat-8 data: A comparison with SAR observations

In this study optical data from satellites Sentinel-2 (S-2), Landsat-8 (L-8), and synthetic aperture radar (SAR) data from Sentinel-1(S-1) have been used to estimate the surface velocity of the Siachen Glacier in J&K Himalaya. Repeat-pass optical and SAR data have been processed employing sub-pixel offset tracking (SOT) approach to decipher surface velocity of glaciers during 2013-2018. It is observed that SOT derived 2-D surface velocity using S-2 and L-8 data pairs show more than 70 % correlation over the entire stretch of the glacier. High correlation among velocities from S-2 and L-8 over two years validates one sensor against another for glacier surface movement studies in the Himalaya. This study reveals that the velocity of the glacier varies from ∼120 ma^-1 to ∼151 ma^-1 during 2013-2018. This study results the movement of glacier using optical sensor and SAR sensor over same geographical zone and similar time zone to evaluate the feature extraction and sensor impact on feature extraction. We have found that all sensors have produced similar results, since data is collected near time frame.