Thomas Trantow, Ute C. Herzfeld

The unique measurement capabilities of ICESat-2 allow high spatiotemporal resolution of complex ice-dynamic processes that occur during a surge. Detailed and precise mapping of height changes on surge glaciers has previously escaped observations from space due to limited resolution of space-borne altimeter data and the surface characteristics of glaciers during surge such as heavy crevassing. This makes geophysical interpretation of deformation and assessment of mass transfer difficult. In this paper, we present an approach that facilitates analysis of the evolution of geophysical processes during a surge, including height changes, crevassing, mass transfer and roughness evolution. We utilize all data from 2 years of ICESat-2 observations collected during the mature phase of the Negribreen Glacier System (NGS) surge in 2019 and 2020. The progression of the NGS surge has resulted in large-scale elevation changes and wide-spread crevassing making it an ideal case study to demonstrate ICESat-2 measurement capabilities, which are maximized when coupled with the Density Dimension Algorithm for Ice (DDA-ice). Results show the expansion of the surge in upper Negribreen which demonstrates the unique ability of ICESat-2/DDA-ice to measure a rapidly changing surge glacier and provide the best estimates for cryospheric changes and their contributions to sea-level rise.