Preprints
https://doi.org/10.5194/tc-2021-3
https://doi.org/10.5194/tc-2021-3

  13 Jan 2021

13 Jan 2021

Review status: a revised version of this preprint is currently under review for the journal TC.

Contrasting regional variability of buried meltwater extent over two years across the Greenland Ice Sheet

Devon Dunmire1, Alison F. Banwell2, Jan T. M. Lenaerts1, and Rajashree Tri Datta1 Devon Dunmire et al.
  • 1Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, USA
  • 2Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, USA

Abstract. The Greenland Ice Sheet (GrIS) rapid mass loss is primarily driven by an increase in meltwater runoff, which highlights the importance of understanding the formation, evolution and impact of meltwater features on the ice sheet. Buried lakes are meltwater features that contain liquid water and exist under layers of snow, firn, and/or ice. These lakes are invisible in optical imagery, challenging the analysis of their evolution and implication for larger GrIS dynamics and mass change. Here, we present a method that uses a convolutional neural network, a deep learning method, to automatically detect buried lakes across the GrIS. For the years 2018 and 2019, we compare total areal extent of both buried and surface lakes across six regions, and use a regional climate model to explain the spatial and temporal differences. We find that the total buried lake extent after the 2019 melt season is 56 % larger than after the 2018 melt season across the entire ice sheet. Northern Greenland observes the largest increase in buried lake extent after the 2019 melt season, which we attribute to late-summer surface melt and high autumn temperatures. We also provide evidence that different processes are responsible for buried lake formation in different regions of the ice sheet. For example, in western Greenland, buried lakes often appear on the surface during the previous melt season, indicating that these features form when surface lakes partially freeze and become insulated as snowfall buries them. In contrast, in southeast Greenland, most buried lakes never appear on the surface, signifying that these features may form due to subsurface penetration of shortwave radiation and/or downward percolation of meltwater. This study helps to provide additional perspective on the potential role of meltwater on GrIS dynamics and mass loss.

Devon Dunmire et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review of manuscript by Dunmire et al.', Anonymous Referee #1, 28 Jan 2021
    • AC1: 'Reply on RC1', Devon Dunmire, 20 Apr 2021
  • RC2: 'Comment on tc-2021-3', Anonymous Referee #2, 12 Feb 2021
    • AC2: 'Reply on RC2', Devon Dunmire, 20 Apr 2021

Devon Dunmire et al.

Devon Dunmire et al.

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Short summary
Here, we automatically detect buried lakes (meltwater lakes buried below layers of snow) across the Greenland Ice Sheet, providing insight into a poorly studied meltwater feature. For 2018 and 2019, we compare areal extent of buried lakes. We find greater buried lake extent in 2019, especially in northern Greenland, which we attribute to late-summer surface melt and high autumn temperatures. We also provide evidence that buried lakes form via different processes across Greenland.