Negribreen, a tidewater glacier located in central eastern Svalbard, began actively surging after it experienced an initial collapse in summer 2016. The surge resulted in horizontal surface velocities of more than 25 m d−1, making it one of the fastest-flowing glaciers in the archipelago. The last surge of Negribreen likely occurred in the 1930s, but due to a long quiescent phase, investigations of this glacier have been limited. As Negribreen is part of the Negribreen Glacier System, one of the largest glacier systems in Svalbard, investigating its current surge event provides important information on surge behaviour among tidewater glaciers within the region. Here, we demonstrate the surge development and discuss triggering mechanisms using time series of digital elevation models (1969–2018), surface velocities (1995–2018), crevasse patterns and glacier extents from various data sources. We find that the active surge results from a four-stage process. Stage 1 (quiescent phase) involves a long-term, gradual geometry change due to high subglacial friction towards the terminus. These changes allow the onset of Stage 2, an accelerating frontal destabilization, which ultimately results in the collapse (Stage 3) and active surge (Stage 4).
Bibliographical noteFunding Information:
This research has been supported by the European Research Council (project: FP/2007-2013/ERC; grant no. 320816) and the European Space Agency Glaciers-CCI, CCI+, ICEFLOW, and EE10 HARMONY projects (4000109873/14/I-NB, 4000127593/19/I/NB, 4000125560/18/I-NS, 4000127656/19/NL/FF/gp). Additional support was provided by the Norwegian Space Centre project Copernicus Glacier Service for Norway (NIT.06.15.5). The study is a contribution to the Svalbard Integrated Arctic Earth Observing System SIOS. Radarsat data were provided by NSC/KSAT under the Norwegian-Canadian Radarsat agreements 2007–2019. ERS-1/2 data were provided by ESA through PRODEX. TanDEM-X DEM was provided through DLR grant IDEM GLAC0435. We are very grateful to USGS for Landsat data, and the Norwegian Polar Institute for the historical map data/DEMs. Acquisition of ASTER images was guided by NASA JPL through the ASTER science team and the Global Land Ice Measurements from Space (GLIMS) initiative. ArcticDEM DEMs provided by the Polar Geospatial Center under NSF-OPP awards 1043681, 1559691 and 1542736. We thank the GoLIVE project for providing free velocity data for the public. We also thank Scientific Editor Hester Jiskoot and two anonymous reviewers for their constructive comments which helped improve the clarity of the manuscript.
Copyright © The Author(s), 2020. Published by Cambridge University Press.
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- Glacier surges
- ice velocity
- remote sensing