Abstract
Abstract. For studying the flow of glaciers and their response to climate change it is important to detect glacier surges. Here, we compute within Google Earth Engine the normalized differences between winter maxima of Sentinel-1 C-band radar backscatter image stacks over subsequent years. We arrive at a global map of annual backscatter changes, which are for glaciers in most cases related to changed crevassing associated with surge-type activity. For our demonstration period 2018–2019 we detected 69 surging glaciers, with many of them not classified so far as surge type. Comparison with glacier surface velocities shows that we reliably find known surge activities. Our method can support operational monitoring of glacier surges and some other special events such as large rock and snow avalanches.
Highlights
Glacier surges are an example of glacier flow instability where the ice velocities strongly increase over a short period of time, typically less than a decade (Meier and Post, 1969)
For 10 glaciers where we Comparison of the surge activity we detect from the radar backscatter difference images with glacier surface velocity suggests that the method we propose for surge detection is reliable
For both Svalbard and Alaska the velocity measurements support most of the surge activity we detect with the backscatter difference images
Summary
Glacier surges are an example of glacier flow instability where the ice velocities strongly increase over a short period of time, typically less than a decade (Meier and Post, 1969). A small fraction of the world’s glaciers are of surge type (Jiskoot et al, 1998; Sevestre and Benn, 2015). Glacier surging is of special scientific and applied interest. Studying glacier surges increases understanding of glacier flow and its instability (e.g. Thøgersen et al, 2019). Glacier surges disturb the link with climate and climatic interpretation of changes in glacier size or mass balance (Zemp et al, 2020). Surges can constitute potential natural hazards (Kääb et al, 2021; Truffer et al, 2021)
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