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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Preprints
https://doi.org/10.5194/tc-2020-251
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2020-251
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  05 Oct 2020

05 Oct 2020

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This preprint is currently under review for the journal TC.

Challenges in predicting Greenland supraglacial lake drainages at the regional scale

Kristin Poinar1 and Lauren C. Andrews2 Kristin Poinar and Lauren C. Andrews
  • 1University at Buffalo, Department of Geology
  • 2NASA Goddard Space Flight Center, Global Modeling and Assimilation Office

Abstract. A leading hypothesis for the mechanism of fast supraglacial lake drainages is that transient extensional stresses briefly allow crevassing in otherwise-compressive ice flow regimes. Lake water can then hydrofracture the crevasse to the base of the ice sheet, and river inputs can maintain this connection as a moulin. If future ice-sheet models are to accurately represent moulins, we must understand their formation processes, timescales, and locations. Here, we use remote-sensing velocity products to constrain the relationship between strain rates and lake drainages across ~ 1600 km2 in Pâkitsoq, western Greenland, between 2002–2019. We find significantly more-extensional background strain rates at moulins associated with fast-draining lakes than at slow-draining or non-draining lake moulins. We test whether moulins in more-extensional background settings drain their lakes earlier, but find insignificant correlation. To investigate the frequency that strain-rate transients are associated with fast lake drainage, we examined Landsat-derived strain rates over 16- and 32-day periods at moulins associated with 240 fast lake drainage events over 18 years. A low signal-to-noise ratio, the presence of water, and the multi-week repeat cycle obscured any resolution of the hypothesized transient strain rates. Our results support the hypothesis that transient strain rates drive fast lake drainages. However, the current generation of ice-sheet velocity products, even when stacked across hundreds of fast lake drainages, cannot resolve these transients. Thus, observational progress in understanding lake drainage initiation will rely on field-based tools such as GPS networks and photogrammetry.

Kristin Poinar and Lauren C. Andrews

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Kristin Poinar and Lauren C. Andrews

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Latest update: 25 Oct 2020
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Short summary
This study addresses Greenland glacier lake drainages, a major international research focus. We analyze ice deformation associated with lake drainages over 18 summers to assess whether precursor events consistently precede lake drainages. We find that currently available remote sensing data products cannot resolve these events and thus that we cannot predict future lake drainages. Thus, future avenues for evaluating this hypothesis will require major field-based GPS or photogrammetry efforts.
This study addresses Greenland glacier lake drainages, a major international research focus. We...
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