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Statistical inference of the ice velocity response to meltwater runoff, terminus position, and bed topography at Helheim Glacier, Greenland
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  • Lizz Ultee,
  • Denis Felikson,
  • Brent Minchew,
  • Leigh A Stearns,
  • Bryan Riel
Lizz Ultee
Massachusetts Institute of Technology

Corresponding Author:[email protected]

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Denis Felikson
NASA Goddard Space Flight Center
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Brent Minchew
Massachusetts Institute of Technology
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Leigh A Stearns
University of Kansas
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Bryan Riel
Massachusetts Institute of Technology
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Abstract

The Greenland Ice Sheet discharges ice to the ocean through hundreds of outlet glaciers.
Recent acceleration of Greenland outlet glaciers has been linked to both oceanic and atmospheric drivers.
Here, we leverage temporally dense observations, regional climate model output, and newly developed time series analysis tools to assess the most important forcings causing ice flow variability at one of the largest Greenland outlet glaciers, Helheim Glacier, from 2009 to 2017. We find that ice speed correlates most strongly with catchment-integrated runoff at seasonal to interannual scales, while multi-annual flow variability correlates most strongly with multi-annual terminus variability. The multiple relevant time scales and the influence of subglacial topography on Helheim Glacier’s dynamics highlight different regimes that can inform modeling and forecasting of its future. Notably, our results suggest that the recent terminus history observed at Helheim is a response to, rather than the cause of, upstream changes.