Seasonal variability in ice velocity driven by subglacial hydrology of Drang Drung Glacier, Western Himalayas

Seasonal glacier dynamics are key to predicting hazards and glacier stability due to short-term events as well as improving glacier models.However, the short-term ice velocity variations remain poorly constrained for slow-moving glaciers in the Himalaya due to the scarcity of in-situ observations and limitations of satellite data and methods.We present seasonal velocity variations of Drang Drung Glacier (western Himalaya) in 2021 using Sentinel-1 phase-based Interferometric Synthetic Aperture Radar (InSAR) and offset tracking.Smoothed velocity estimates reveal ~400 % seasonal variability (313 m yr 1), with speedups in spring and autumn and slowdowns in summer and winter.We relate these patterns to changes in radar backscatter and seasonal widening of the proglacial stream observed in Planet imagery.To interpret the mechanisms, we simulate the evolution with the Subglacial Hydrology and