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Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic Bottom Water

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Silvano, A, Rintoul, SR ORCID: 0000-0002-7055-9876, Pena-Molino, B ORCID: 0000-0003-1587-1696, Hobbs, WR ORCID: 0000-0002-2061-0899, van Wijk, E, Aoki, S, Tamura, T and Williams, GD ORCID: 0000-0003-1769-8356 2018 , 'Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic Bottom Water' , Science Advances, vol. 4, no. 4 , pp. 1-12 , doi: 10.1126/sciadv.aap9467.

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Abstract

Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence of strong polynyas, DSW is not formed on the Sabrina Coast in East Antarctica and in the Amundsen Sea in West Antarctica. Using a simple ocean model driven by observed forcing, we show that freshwater input from basal melt of ice shelves partially offsets the salt flux by sea ice formation in polynyas found in both regions, preventing full-depth convection and formation of DSW. In the absence of deep convection, warm water that reaches the continental shelf in the bottom layer does not lose much heat to the atmosphere and is thus available to drive the rapid basal melt observed at the Totten Ice Shelf on the Sabrina Coast and at the Dotson and Getz ice shelves in the Amundsen Sea. Our results suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise.

Item Type: Article
Authors/Creators:Silvano, A and Rintoul, SR and Pena-Molino, B and Hobbs, WR and van Wijk, E and Aoki, S and Tamura, T and Williams, GD
Keywords: Antarctic, oceanography, ocean-ice shelf interaction
Journal or Publication Title: Science Advances
Publisher: American Association for the Advancement of Science (A A A S)
ISSN: 2375-2548
DOI / ID Number: 10.1126/sciadv.aap9467
Copyright Information:

Copyright 2018 The Authors. Licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) https://creativecommons.org/licenses/by-nc/4.0/

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