Recent Surge Behavior of Walsh Glacier Revealed by Remote Sensing Data.

Xiyou Fu,Jianmin Zhou

doi:10.3390/s20030716

Abstract

Many surge-type glaciers are present on the St. Elias Mountains, but a detailed study on the surge behavior of the glaciers is still missing. In this study, we used remote sensing data to reveal detailed glacier surge behavior, focusing on the recent surge at Walsh Glacier, which was reported to have surged once in the 1960s. Glacial velocities were derived using a cross-correlation algorithm, and changes in the medial moraines were interpreted based on Landsat images. The digital elevation model (DEM) difference method was applied to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEMs to evaluate the surface elevation of the glacier. The results showed that the surge initiated near the conjunction of the eastern and northern branches, and then quickly spread downward. The surge period was almost three years, with an active phase of less than two years. The advancing speed of the surge front was much large than the maximum ice velocity of ≈14 m/d observed during the active phase. Summer speed-ups and a winter speed-up in ice velocity were observed from velocity data, with the speed-ups being more obvious during the active phase. Changes in the glacier velocity and the medial moraines suggested that the eastern branch was more affected by the surge. The DEM differencing results showed that the receiving zone thickened up to about 140 m, and the upstream reservoir zone became thinner. These surge behaviors, as characterized by remote sensing data, gave us more detailed insights into the surge dynamics of Walsh Glacier.

Highlights

Surge-type glaciers experience well-defined, cyclical non-steady flow, alternating between a short active phase, usually characterized by rapid terminus advance, and a longer quiescent phase, characterized by terminus stagnation or retreat [1,2]
The results showed that the surge initiated near the conjunction of the eastern and northern branches, and quickly spread downward
Summer speed-ups and a winter speed-up in ice velocity were observed from velocity data, with the speed-ups being more obvious during the active phase

Summary

Introduction

Surge-type glaciers experience well-defined, cyclical non-steady flow, alternating between a short active phase (months to years), usually characterized by rapid terminus advance, and a longer quiescent phase (years to decades), characterized by terminus stagnation or retreat [1,2]. During the active phase of a typical glacial surge, a large portion of the ice mass is rapidly transported from a reservoir area to a receiving area, leading to dramatic changes in glacial surface elevation and sometimes terminus advance. In the quiescent phase after the surge, ice flow slows or becomes stagnant in the lower part, leading to ice mass accumulation upstream, and retreat and thinning in the lower stream. Due to the significant volume of ice mass that is transported rapidly downstream during the surge period, glacial surges may cause disasters. In Western China, the surge-induced avalanche of Karayaylak Glacier destroyed more than 1000 ha of grazing meadow

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Results

Discussion

Conclusion