Investigating Recent Surface Velocity Responses to Glacier Thickness Changes in High Mountain Asia, 2013-2019

Abstract:

High-mountain Asia glaciers influence downstream hydrologic and ecological processes and supply critical water resources to populations in catchment areas. Understanding how these glaciers respond to climate perturbations helps downstream communities predict and adapt to a hydrologic cycle altered by warming-induced glacier mass loss.

Glacier surface velocities offer important information about glacier dynamics, mass transfer within glaciers, and interactions between glaciers, local terrain, and climate change. This project uses surface velocities from Global Land Ice Velocity Extraction from Landsat8 (GoLIVE) datasets to examine the magnitudes and timescales of glacier responses to thickness perturbations such as snow avalanches, anomalous winter storms, and calving events for a selection of glaciers in the eastern Himalaya from 2013-2019. As a secondary objective, we evaluate the suitability of GoLIVE datasets for further surface velocity studies of individual glaciers in mid-latitude, monsoon-driven climates such as the eastern Himalaya. We examine velocity convergence and divergence along glacier centerlines and transects, pre and post mass changes, to define patterns and timescales of mass transfer. Treating abrupt changes in thickness as proxies for climate signals such as increases or decreases in accumulation over time, we observe the nature and timescale of surface velocity responses among glaciers and how glacier attributes such as area, length and terminus type affect that response.

By analyzing spatial and temporal variations in glacier surface velocities, this work seeks to clarify the mechanisms by which glaciers assimilate thickness perturbations and return to equilibrium after mass-loading or mass-loss events. Further constraint of these mechanisms permits a greater understanding of glacier sensitivity to climate in high-mountain Asia and supports glacier modeling efforts to improve quantification of glacier contributions to water resources over time.