Grounding line migration through the calving season at Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry

Surui Xie, Timothy H. Dixon, Denis Voytenko, Fanghui Deng, David M. Holland

Research output: Contribution to journalArticle

Abstract

Ice velocity variations near the terminus of Jakobshavn Isbræ, Greenland, were observed with a terrestrial radar interferometer (TRI) during three summer campaigns in 2012, 2015, and 2016. We estimate a ∼1 km wide floating zone near the calving front in early summer of 2015 and 2016, where ice moves in phase with ocean tides. Digital elevation models (DEMs) generated by the TRI show that the glacier front here was much thinner (within 1 km of the glacier front, average ice surface is ∼100 and ∼110m above local sea level in 2015 and 2016, respectively) than ice upstream (average ice surface is >150m above local sea level at 2-3 km to the glacier front in 2015 and 2016). However, in late summer 2012, there is no evidence of a floating ice tongue in the TRI observations. Average ice surface elevation near the glacier front was also higher, ∼125m above local sea level within 1 km of the glacier front. We hypothesize that during Jakobshavn Isbræ's recent calving seasons the ice front advances ∼3 km from winter to spring, forming a >1 km long floating ice tongue. During the subsequent calving season in mid- and late summer, the glacier retreats by losing its floating portion through a sequence of calving events. By late summer, the entire glacier is likely grounded. In addition to ice velocity variation driven by tides, we also observed a velocity variation in the mélange and floating ice front that is non-parallel to long-term ice flow motion. This cross-flow-line signal is in phase with the first time derivative of tidal height and is likely associated with tidal currents or bed topography.

Original languageEnglish (US)
Pages (from-to)1387-1400
Number of pages14
JournalCryosphere
Volume12
Issue number4
DOIs
StatePublished - Apr 17 2018

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grounding line
radar interferometry
ice
glacier
floating ice
interferometer
summer
radar
sea level
glacier retreat
ocean tide
ice flow
tidal current
digital elevation model
tide
topography
winter

ASJC Scopus subject areas

  • Water Science and Technology
  • Earth-Surface Processes

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Grounding line migration through the calving season at Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry. / Xie, Surui; Dixon, Timothy H.; Voytenko, Denis; Deng, Fanghui; Holland, David M.

In: Cryosphere, Vol. 12, No. 4, 17.04.2018, p. 1387-1400.

Research output: Contribution to journalArticle

Xie, Surui ; Dixon, Timothy H. ; Voytenko, Denis ; Deng, Fanghui ; Holland, David M. / Grounding line migration through the calving season at Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry. In: Cryosphere. 2018 ; Vol. 12, No. 4. pp. 1387-1400.
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abstract = "Ice velocity variations near the terminus of Jakobshavn Isbr{\ae}, Greenland, were observed with a terrestrial radar interferometer (TRI) during three summer campaigns in 2012, 2015, and 2016. We estimate a ∼1 km wide floating zone near the calving front in early summer of 2015 and 2016, where ice moves in phase with ocean tides. Digital elevation models (DEMs) generated by the TRI show that the glacier front here was much thinner (within 1 km of the glacier front, average ice surface is ∼100 and ∼110m above local sea level in 2015 and 2016, respectively) than ice upstream (average ice surface is >150m above local sea level at 2-3 km to the glacier front in 2015 and 2016). However, in late summer 2012, there is no evidence of a floating ice tongue in the TRI observations. Average ice surface elevation near the glacier front was also higher, ∼125m above local sea level within 1 km of the glacier front. We hypothesize that during Jakobshavn Isbr{\ae}'s recent calving seasons the ice front advances ∼3 km from winter to spring, forming a >1 km long floating ice tongue. During the subsequent calving season in mid- and late summer, the glacier retreats by losing its floating portion through a sequence of calving events. By late summer, the entire glacier is likely grounded. In addition to ice velocity variation driven by tides, we also observed a velocity variation in the m{\'e}lange and floating ice front that is non-parallel to long-term ice flow motion. This cross-flow-line signal is in phase with the first time derivative of tidal height and is likely associated with tidal currents or bed topography.",
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