TCD

The Cryosphere Discussions

TCD

The Cryosphere Discuss.

1994-0440

Göttingen, Germany

10.5194/tc-2019-35

Sensitivity of submarine melting on North East Greenland towards ocean forcing

Anhaus

Philipp

https://orcid.org/0000-0002-0671-8545

¹ ² ⁴ Smedsrud

Lars H.

https://orcid.org/0000-0001-7391-0740

¹ ² Årthun

Marius

https://orcid.org/0000-0003-4500-1691

¹ ² Straneo

Fiammetta

https://orcid.org/0000-0002-1735-2366

Geophysical Institute, University of Bergen, Norway

Bjerknes Centre for Climate Research, Bergen, Norway

Scripps Institution of Oceanography, La Jolla, California, USA

now at: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany

10 04 2019

2019 1 29

2019

This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/

This article is available from https://tc.copernicus.org/preprints/tc-2019-35/

The full text article is available as a PDF file from https://tc.copernicus.org/preprints/tc-2019-35/tc-2019-35.pdf

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.

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