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Circulation of modified Circumpolar Deep Water and basal melt beneath the Amery Ice Shelf, East Antarctica

Circulation of modified Circumpolar Deep Water and basal melt beneath the Amery Ice Shelf, East Antarctica
Circulation of modified Circumpolar Deep Water and basal melt beneath the Amery Ice Shelf, East Antarctica
Antarctic ice sheet mass loss has been linked to an increase in oceanic heat supply, which enhances basal melt and thinning of ice shelves. Here we detail the interaction of modified Circumpolar Deep Water (mCDW) with the Amery Ice Shelf, the largest ice shelf in East Antarctica, and provide the first estimates of basal melting due to mCDW. We use subice shelf ocean observations from a borehole site (AM02) situated ?70 km inshore of the ice shelf front, together with open ocean observations in Prydz Bay. We find that mCDW transport into the cavity is about 0.22?±?0.06 Sv (1 Sv?=?106 m3 s?1). The inflow of mCDW drives a net basal melt rate of up to 2?±?0.5 m yr?1 during 2001 (23.9?±?6.52 Gt yr?1 from under about 12,800 km2 of the north-eastern flank of the ice shelf). The heat content flux by mCDW at AM02 shows high intra-annual variability (up to 40%). Our results suggest two main modes of subice shelf circulation and basal melt regimes: (1) the “ice pump”/high salinity shelf water circulation, on the western flank and (2) the mCDW meltwater-driven circulation in conjunction with the “ice pump,” on the eastern flank. These results highlight the sensitivity of the Amery's basal melting to changes in mCDW inflow. Improved understanding of such ice shelf-ocean interaction is crucial to refining projections of mass loss and associated sea level rise.
mCDW, Amery Ice Shelf, basal melt
2169-9275
3098-3112
Herraiz-Borreguero, Laura
faa962ba-19f8-4cf3-83be-ee4972fdbe9f
Coleman, Richard
d5b99205-531b-4265-b352-82c05f16bf7f
Allison, Ian
f07fb068-cb89-4084-bc63-c35e1307c801
Rintoul, Stephen R.
ff078a21-d6cd-45bf-8c8f-f81f2e8ae410
Craven, Mike
0beb9ab2-f7ba-49ff-ba40-5d35e3f96387
Williams, Guy D.
0a237221-85c5-48b9-b4ca-a06a3b5074e5
Herraiz-Borreguero, Laura
faa962ba-19f8-4cf3-83be-ee4972fdbe9f
Coleman, Richard
d5b99205-531b-4265-b352-82c05f16bf7f
Allison, Ian
f07fb068-cb89-4084-bc63-c35e1307c801
Rintoul, Stephen R.
ff078a21-d6cd-45bf-8c8f-f81f2e8ae410
Craven, Mike
0beb9ab2-f7ba-49ff-ba40-5d35e3f96387
Williams, Guy D.
0a237221-85c5-48b9-b4ca-a06a3b5074e5

Herraiz-Borreguero, Laura, Coleman, Richard, Allison, Ian, Rintoul, Stephen R., Craven, Mike and Williams, Guy D. (2015) Circulation of modified Circumpolar Deep Water and basal melt beneath the Amery Ice Shelf, East Antarctica. Journal of Geophysical Research: Oceans, 120 (4), 3098-3112. (doi:10.1002/2015JC010697).

Record type: Article

Abstract

Antarctic ice sheet mass loss has been linked to an increase in oceanic heat supply, which enhances basal melt and thinning of ice shelves. Here we detail the interaction of modified Circumpolar Deep Water (mCDW) with the Amery Ice Shelf, the largest ice shelf in East Antarctica, and provide the first estimates of basal melting due to mCDW. We use subice shelf ocean observations from a borehole site (AM02) situated ?70 km inshore of the ice shelf front, together with open ocean observations in Prydz Bay. We find that mCDW transport into the cavity is about 0.22?±?0.06 Sv (1 Sv?=?106 m3 s?1). The inflow of mCDW drives a net basal melt rate of up to 2?±?0.5 m yr?1 during 2001 (23.9?±?6.52 Gt yr?1 from under about 12,800 km2 of the north-eastern flank of the ice shelf). The heat content flux by mCDW at AM02 shows high intra-annual variability (up to 40%). Our results suggest two main modes of subice shelf circulation and basal melt regimes: (1) the “ice pump”/high salinity shelf water circulation, on the western flank and (2) the mCDW meltwater-driven circulation in conjunction with the “ice pump,” on the eastern flank. These results highlight the sensitivity of the Amery's basal melting to changes in mCDW inflow. Improved understanding of such ice shelf-ocean interaction is crucial to refining projections of mass loss and associated sea level rise.

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Accepted/In Press date: 8 April 2015
Published date: 26 April 2015
Keywords: mCDW, Amery Ice Shelf, basal melt
Organisations: Physical Oceanography

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Local EPrints ID: 398659
URI: http://eprints.soton.ac.uk/id/eprint/398659
ISSN: 2169-9275
PURE UUID: 3afd0af0-c6af-4ac3-b37a-ba2ade9251f5

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Date deposited: 28 Jul 2016 15:02
Last modified: 15 Mar 2024 01:38

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Contributors

Author: Laura Herraiz-Borreguero
Author: Richard Coleman
Author: Ian Allison
Author: Stephen R. Rintoul
Author: Mike Craven
Author: Guy D. Williams

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