Sensitivity of submarine melting on North East Greenland towards ocean forcing

Philipp Anhaus, Lars H. Smedsrud, Marius Årthun, Fiammetta Straneo
2019 The Cryosphere Discussions  
<p><strong>Abstract.</strong> 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&amp;thinsp;°C at 610&amp;thinsp;m depth. The AW present in the cavity thus has the potential to drive submarine melting along the ice base. Here, we simulate melt
more » ... ates from the 79NG with a 1D numerical Ice Shelf Water (ISW) plume model. A meltwater plume is initiated at the grounding line depth (600&amp;thinsp;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&amp;ndash;76&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup> within 10&amp;thinsp;km of the grounding line. Within a zone of rapid decay between 10&amp;thinsp;km and 20&amp;thinsp;km melt rates drop to roughly 6&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup>. Further downstream, melt rates are between 15&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup> and 6&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup>. The melt-rate sensitivity to variations in AW temperatures is assessed by forcing the model with AW temperatures between 0.1&amp;ndash;1.4&amp;thinsp;°C, as identified from the ECCOv4 ocean state estimate. The melt rates increase linearly with rising AW temperature, ranging from 10&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup> to 21&amp;thinsp;m&amp;thinsp;yr<sup>&amp;minus;1</sup> along the centerline. The corresponding freshwater flux ranges between 11&amp;thinsp;km<sup>3</sup>&amp;thinsp;yr<sup>&amp;minus;1</sup> (0.4&amp;thinsp;mSv) and 30&amp;thinsp;km<sup>3</sup>&amp;thinsp;yr<sup>&amp;minus;1</sup> (1.0&amp;thinsp;mSv), which is 5&amp;thinsp;% and 12&amp;thinsp;% 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.</p>
doi:10.5194/tc-2019-35 fatcat:hyiz6nxx5zcw3mloaqmptem5zu