Preprints
https://doi.org/10.5194/tc-2019-35
https://doi.org/10.5194/tc-2019-35

  10 Apr 2019

10 Apr 2019

Review status: this preprint was under review for the journal TC but the revision was not accepted.

Sensitivity of submarine melting on North East Greenland towards ocean forcing

Philipp Anhaus1,2,a, Lars H. Smedsrud1,2, Marius Årthun1,2, and Fiammetta Straneo3 Philipp Anhaus et al.
  • 1Geophysical Institute, University of Bergen, Norway
  • 2Bjerknes Centre for Climate Research, Bergen, Norway
  • 3Scripps Institution of Oceanography, La Jolla, California, USA
  • anow at: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany

Abstract. The Nioghalvfjerdsbræ (79NG) is a floating ice tongue on Northeast Greenland draining a large part of the Greenland Ice Sheet. A CTD profile from a rift on the ice tongue close to the northern front shows that Atlantic Water (AW) is present in the cavity below, with maximum temperature of approximately 1 °C at 610 m depth. The AW present in the cavity thus has the potential to drive submarine melting along the ice base. Here, we simulate melt rates from the 79NG with a 1D numerical Ice Shelf Water (ISW) plume model. A meltwater plume is initiated at the grounding line depth (600 m) and rises along the ice base as a result of buoyancy contrast to the underlying AW. Ice melts as the plume entrains the warm AW. Maximum simulated melt rates are 50–76 m yr−1 within 10 km of the grounding line. Within a zone of rapid decay between 10 km and 20 km melt rates drop to roughly 6 m yr−1. Further downstream, melt rates are between 15 m yr−1 and 6 m yr−1. The melt-rate sensitivity to variations in AW temperatures is assessed by forcing the model with AW temperatures between 0.1–1.4 °C, as identified from the ECCOv4 ocean state estimate. The melt rates increase linearly with rising AW temperature, ranging from 10 m yr−1 to 21 m yr−1 along the centerline. The corresponding freshwater flux ranges between 11 km3 yr−1 (0.4 mSv) and 30 km3 yr−1 (1.0 mSv), which is 5 % and 12 % of the total freshwater flux from the Greenland Ice Sheet since 1995, respectively. Our results improve the understanding of processes driving submarine melting of marine-terminating glaciers around Greenland, and its sensitivity to changing ocean conditions.

Philipp Anhaus et al.

 
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Philipp Anhaus et al.

Data sets

Submarine melt rates, plume dynamics, hydrography, and ice base topography at 79NG P. Anhaus, L. H. Smedsrud, M. Årthun, and F. Straneo https://doi.pangaea.de/10.1594/PANGAEA.898679

Model code and software

Submarine melt rates, plume dynamics, hydrography, and ice base topography at 79NG P. Anhaus, L. H. Smedsrud, M. Årthun, and F. Straneo https://doi.pangaea.de/10.1594/PANGAEA.898679

Philipp Anhaus et al.

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Short summary
Atlantic Water flows towards the Arctic and under floating glaciers on Greenland. Observations in a rift on the 79 North Glacier show presence of such water with temperature of 1 °C at 600 m. We simulate how this warm water melts the floating ice. Melt rates are largest where the glacier starts floating, are smaller where the water rises, and increase linearly with rising ocean temperature. Our results improve the understanding of ocean processes driving melting of floating glaciers.