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Calving of a large Greenlandic tidewater glacier has complex links to meltwater plumes and mélange
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  • Samuel Cook,
  • Poul Christoffersen,
  • Martin Truffer,
  • Thomas Russell Chudley,
  • Antonio Abellan
Samuel Cook
Université Grenoble Alpes

Corresponding Author:[email protected]

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Poul Christoffersen
University of Cambridge
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Martin Truffer
University of Alaska Fairbanks
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Thomas Russell Chudley
Scott Polar Research Institute
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Antonio Abellan
Institute of Applied Geosciences, University of Leeds
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Calving and solid ice discharge into fjords account for approximately half of the annual net ice loss from the Greenland Ice Sheet, but these processes are rarely observed. To gain insights into the spatio-temporal nature of calving, we use a terrestrial radar interferometer to derive a three-week record of 8,026 calving events from Store Glacier, including the transition between a mélange-filled and ice-free fjord. We show that calving rates double across this transition and that the interferometer record is in good agreement with volumetric estimates of calving losses from contemporaneous UAV surveys. We report significant variations in calving activity over time, which obfuscate any simple power-law relationship. While there is a statistically significant relationship between surface melt and the number of calving events, no such relationship exists between surface melt and the volume of these events. Similarly, we find a 70% increase in the number of calving events in the presence of visible meltwater plumes, but only a 3% increase in calving volumes. While calving losses appear to have no clear single control, we find a bimodal distribution of iceberg sizes due to small sections of ice breaking off the subaerial part of the front and large capsizing icebergs forming by full-thickness failure. Whereas previous work has hypothesised that tidewater glaciers can be grouped according to whether they calve predominantly by the former or latter mechanism, our observations indicate that calving here inherently comprises both, and that the dominant process can change over relatively short periods.
Apr 2021Published in Journal of Geophysical Research: Earth Surface volume 126 issue 4. 10.1029/2020JF006051