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

Basal melt, seasonal water mass transformation, ocean current variability, and deep convection processes along the Amery Ice Shelf calving front, East Antarctica
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-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.
2169-9275
4946–4965
Herraiz-Borreguero, L.
f4573b48-5d8c-403f-9460-5902fe5fdeb3
Church, J.A.
7ceb1eeb-54c5-4fb0-8066-af6a187519fc
Allison, I.
86ffece2-2873-4ae4-8bb0-ff0ee391c2af
Peña-Molino, B.
3cc33760-734f-45bf-bec4-18c19feee3b1
Coleman, R.
c63e5ff2-8275-46af-ba2d-644e49fec534
Tomczak, M.
65415aaf-25f3-402d-95f0-adf73895fc84
Craven, M.
92add309-7bcd-4d4e-9706-f21e37505fae
Herraiz-Borreguero, L.
f4573b48-5d8c-403f-9460-5902fe5fdeb3
Church, J.A.
7ceb1eeb-54c5-4fb0-8066-af6a187519fc
Allison, I.
86ffece2-2873-4ae4-8bb0-ff0ee391c2af
Peña-Molino, B.
3cc33760-734f-45bf-bec4-18c19feee3b1
Coleman, R.
c63e5ff2-8275-46af-ba2d-644e49fec534
Tomczak, M.
65415aaf-25f3-402d-95f0-adf73895fc84
Craven, M.
92add309-7bcd-4d4e-9706-f21e37505fae

Herraiz-Borreguero, L., Church, J.A., Allison, I., Peña-Molino, B., Coleman, R., Tomczak, M. and Craven, M. (2016) Basal melt, seasonal water mass transformation, ocean current variability, and deep convection processes along the Amery Ice Shelf calving front, East Antarctica. Journal of Geophysical Research: Oceans, 121 (7), 4946–4965. (doi:10.1002/2016JC011858).

Record type: Article

Abstract

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 = 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.

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Herraiz-Borreguero_et_al-2016-Journal_of_Geophysical_Research__Oceans - Version of Record
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Accepted/In Press date: 9 June 2016
e-pub ahead of print date: 17 July 2016
Organisations: Ocean and Earth Science, Physical Oceanography

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Local EPrints ID: 411919
URI: http://eprints.soton.ac.uk/id/eprint/411919
ISSN: 2169-9275
PURE UUID: 5bfbb049-2f5b-4cd6-9e14-f3443f8c463b

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Date deposited: 29 Jun 2017 16:32
Last modified: 09 Jan 2022 08:46

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Contributors

Author: L. Herraiz-Borreguero
Author: J.A. Church
Author: I. Allison
Author: B. Peña-Molino
Author: R. Coleman
Author: M. Tomczak
Author: M. Craven

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