Herraiz-Borreguero_et_al-2016-Journal_of_Geophysical_Research__Oceans.pdf (6.26 MB)
Basal melt, seasonal water mass transformation, ocean current variability, and deep convection processes along the Amery Ice Shelf calving front, East Antarctica
journal contribution
posted on 2023-05-18, 22:13 authored by Laura Herraiz-BorregueroLaura Herraiz-Borreguero, Church, JA, Ian AllisonIan Allison, Beatriz Pena-MolinoBeatriz Pena-Molino, Richard ColemanRichard Coleman, Tomczak, M, Craven, MDespite 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 = 106 m3 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.
Funding
Australian Research Council
History
Publication title
Journal of Geophysical Research: OceansVolume
121Issue
7Pagination
4946-4965ISSN
2169-9275Department/School
Institute for Marine and Antarctic StudiesPublisher
Wiley-Blackwell Publishing, Inc.Place of publication
United StatesRights statement
Copyright 2016 American Geophysical UnionRepository Status
- Open