| Summary: | The Negribreen Glacier System on the east coast of Spitsbergen, Svalbard, has been actively surging since 2016, i.e., during the entire lifetime of ICESat-2 (launched in September 2018). The progression of Negribreen’s surge throughout the glacier system has resulted in large-scale elevation changes and wide-spread crevassing, which is ideally mapped and analyzed using ICESat-2 measurements processed by the Density Dimension Algorithm for Ice (DDA-ice) (see Herzfeld et al. 2016, IEEE TGRS, and Herzfeld et al., 2022, Science of Remote Sensing). In this analysis, we quantify how Negribreen has been evolving in its mature surge phase over the course of 2019 and 2020. Using ICESat-2 data, together with airborne field data and Sentinel-1-derived velocity data, we quantify large-scale effects such as elevation-change and mass transfer through the system, as well as smaller-scale effects afforded by high-resolution data products of the DDA-ice such as crevasse characterization, surface roughness and changes thereof. Results show the expansion of the surge in upper Negribreen where increased crevassing has occurred along with height change rates nearing 30 m/year. In addition, fresh surge crevasses formed along the margin between the surging ice of Negribreen and non-surging ice of neighboring Ordonnansbreen. Finally, increased surge activity found on inflowing glaciers from the Filchnerfonna accumulation zone suggest that surge effects may continue to expand up glacier leading to further disintegration of the ice system with continued mass loss.
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