Investigating seasonal velocity variations of debris-covered and debris-free glaciers in High Mountain Asia

Glacier flow is a sensitive indicator of mass balance and dynamics. Monitoring changes in glacier flow at high temporal resolutions enables understanding of the glacier’s sensitivity to short term climate variability. Previous studies have found that the glaciers in High Mountain Asia (HMA) are in tendency slowing down concomitant to losing mass at an accelerating rate. However, only few investigated seasonal velocity variations and the difference between debris-covered and debris-free glaciers flow dynamics. We focus on four debris-covered and four debris-free glaciers across HMA, which have different climates, glaciological, topographic and terminating environments. The four debris-covered glaciers include Kekesay, Satopanth, Khumbu and Xibu glaciers. The four debris-free glaciers include Tuyuksu, Abramov, Petrov and Yanong glaciers. Sentinel-1 and -2 images were selected to calculate the glacial velocities using the feature tracking module provided by CARST (Cryosphere And Remote Sensing Toolkit) (Zheng et al., 2021). We then developed a novel statistical method to extract the seasonally resolved glacial velocity time series. We found clear seasonal signals in the velocities for some of the glaciers and suggest that changes in the subglacial drainage system are driving the seasonal variations in velocities. This mechanism will likely continue in the future due to increased surface melt rates and changes in precipitation patterns across HMA. We also highlight that icefalls may alter the glaciers dynamics by blocking the development of subglacial drainage channels, and thus seasonal propagation of velocities. Our novel methodology enables further understanding of short term dynamics of debris-covered and debris-free glaciers, which is crucial to capture in order to study the response of glaciers today, and in the future to climate change in HMA.

 

Zheng, W., Durkin, W. J., Melkonian, A. K., & Pritchard, M. E. (2021, March 9). Cryosphere And Remote Sensing Toolkit (CARST) v2.0.0a1 (Version v2.0.0a1). Zenodo. http://doi.org/10.5281/zenodo.3475693