Basal melt, seasonal water mass transformation, ocean current variability, and deep convection processes along the Amery Ice Shelf calving front, East Antarctica

Despite the Amery Ice Shelf (AIS) being the third largest ice shelf in Antarctica, the seasonal variability of the physical processes involved in the AIS-ocean interaction remains undocumented and a robust observational, oceanographic-based basal melt rate estimate has been lacking. Here we use year...

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Bibliographic Details
Published in:Journal of Geophysical Research: Oceans
Main Authors: Herraiz-Borreguero, L, Church, JA, Allison, I, Pena-Molino, B, Coleman, R, Tomczak, M, Craven, M
Format: Article in Journal/Newspaper
Language:English
Published: Wiley-Blackwell Publishing, Inc. 2016
Subjects:
Earth Sciences
Oceanography
Physical Oceanography
Antarctic
East Antarctica
Amery
Amery Ice Shelf
West Ice Shelf
Antarc*
Antarctica
Antarctica Journal
Ice Shelf
Online Access:https://doi.org/10.1002/2016JC011858
http://ecite.utas.edu.au/111337
Description
Summary:Despite the Amery Ice Shelf (AIS) being the third largest ice shelf in Antarctica, the seasonal variability of the physical processes involved in the AIS-ocean interaction remains undocumented and a robust observational, oceanographic-based basal melt rate estimate has been lacking. Here we use year-long time series of water column temperature, salinity, and horizontal velocities measured along the ice shelf front from 2001 to 2002. Our results show strong zonal variations in the distribution of water masses along the ice shelf front: modified Circumpolar Deep Water (mCDW) arrives in the east, while in the west, Ice Shelf Water (ISW) and Dense Shelf Water (DSW) formed in the Mackenzie polynya dominate the water column. Baroclinic eddies, formed during winter deep convection (down to 1100 m), drive the inflow of DSW into the ice shelf cavity. Our net basal melt rate estimate is 57.4 25.3 Gt yr −1 (1 0.4 m yr −1 ), larger than previous modeling-based and glaciological-based estimates, and results from the inflow of DSW (0.52 0.38 Sv; 1 Sv = 10 6 m 3 s −1 ) and mCDW (0.22 0.06 Sv) into the cavity. Our results highlight the role of the Mackenzie polynya in the seasonal exchange of water masses across the ice shelf front, and the role of the ISW in controlling the formation rate and thermohaline properties of DSW. These two processes directly impact on the ice shelf mass balance, and on the contribution of DSW/ISW to the formation of Antarctic Bottom Water.

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