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

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 Ant...

Full description

Bibliographic Details
Published in:Science Advances
Main Authors: Silvano, A, Rintoul, SR, Pena-Molino, B, Hobbs, WR, van Wijk, E, Aoki, S, Tamura, T, Williams, GD
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (A A A S) 2018
Subjects:
Antarctic
oceanography
ocean-ice shelf interaction
The Antarctic
East Antarctica
West Antarctica
Amundsen Sea
Getz
Sabrina Coast
Antarc*
Antarctica
Ice Sheet
Ice Shelf
Ice Shelves
Sea ice
Totten Ice Shelf
Online Access:https://eprints.utas.edu.au/26429/
https://eprints.utas.edu.au/26429/1/125485%20final.pdf
Description
Summary: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.

Similar Items