Quantifying heterogeneous glacier dynamics in Lunana, Bhutan, using high-spatiotemporal resolution satellite imagery
Assigned Session: FS 3.134: Remote sensing to capture the dynamics of mountain cryosphere
Abstract ID: 3.10955 | Accepted as Talk | Requested as: Talk | TBA | TBA
Alex Hyde
Rachel, Carr (1); Stuart, Dunning (1); Van Wyk de Vries, Maximillian (1)
(1) Newcastle University, Claremont Rd, NE1 7RU Newcastle Upon Tyne, GB
Abstract
Quantifying the response of lake-terminating glaciers in High Mountain Asia to climate change is crucial for forecasting glacial hazards and future water resource availability. The Lunana region in Bhutan, which hosts four large glacial lakes with significant hazard potential, is an important area of study. Using the PlanetScope CubeSat constellation (3m spatial resolution), we mapped ice velocities at monthly intervals from 2017 -2023 . We reveal that the disintegration of Thorthormi Glacier’s ice tongue in 2022 coincided with year -on -year acceleration at its terminus and increased seasonal variability in surface velocities. This acceleration is attributed to reduced basal drag due to thinning, which resulted in an increasing proportion of the terminus reaching flotation, evidenced by the calving tabular icebergs. While the other three lake terminating glaciers; Bechung, Raphstreng, and Lugge exhibited similar retreat rates, Bechung and Raphstreng showed notably higher seasonal variability compared to Lugge. At higher elevations, all glaciers showed a decelerating velocity trend, this is attributed to surface thinning and reducing driving stresses. We show that accelerating trends in surface velocity can be a precursor to accelerated rates of retreat and rapid lake expansion, highlighting the importance of continuous monitoring of lake terminating glacier ice velocities in the Himalayas
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