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Wind-driven export of Weddell Sea slope water

Wind-driven export of Weddell Sea slope water
Wind-driven export of Weddell Sea slope water

The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the three-dimensional oceanic circulation. Here we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and 5 years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh, westward flowing current. This is often bottom-intensified between 600 and 2000 dbar with velocities of over 20 cm s−1, transporting an average of 1.5 ± 1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modeled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual time scales the density of the slope current is negatively correlated (r > 0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 6–13 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind stress/export relationship and find that it is most consistent with wind-driven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediate-level waters to lower latitudes.

Weddell Sea, Slope Current, Antarctic Circumpolar Current
7530-7546
Meijers, A.J.S
54f3c304-f232-4eec-9f55-53d9b77120ed
Meredith, M.P .
9a50f82d-4e7d-4d52-a51d-a293193acb14
Abrahamsen, E.P.
91cafab8-17c1-473e-bdc3-3e24b3f24fbe
Maqueda, M.A.M.
72e0ec10-7e71-4fb1-973d-36bebc97c2e0
Jones, D.C.
0a41f500-6a92-45b2-9490-d1b3cadbb7af
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Meijers, A.J.S
54f3c304-f232-4eec-9f55-53d9b77120ed
Meredith, M.P .
9a50f82d-4e7d-4d52-a51d-a293193acb14
Abrahamsen, E.P.
91cafab8-17c1-473e-bdc3-3e24b3f24fbe
Maqueda, M.A.M.
72e0ec10-7e71-4fb1-973d-36bebc97c2e0
Jones, D.C.
0a41f500-6a92-45b2-9490-d1b3cadbb7af
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6

Meijers, A.J.S, Meredith, M.P ., Abrahamsen, E.P., Maqueda, M.A.M., Jones, D.C. and Naveira Garabato, A.C. (2016) Wind-driven export of Weddell Sea slope water. Journal of Geophysical Research: Oceans, 121 (10), 7530-7546. (doi:10.1002/2016JC011757).

Record type: Article

Abstract

The export of waters from the Weddell Gyre to lower latitudes is an integral component of the southern subpolar contribution to the three-dimensional oceanic circulation. Here we use more than 20 years of repeat hydrographic data on the continental slope on the northern tip of the Antarctic Peninsula and 5 years of bottom lander data on the slope at 1000 m to show the intermittent presence of a relatively cold, fresh, westward flowing current. This is often bottom-intensified between 600 and 2000 dbar with velocities of over 20 cm s−1, transporting an average of 1.5 ± 1.5 Sv. By comparison with hydrography on the continental slope within the Weddell Sea and modeled tracer release experiments we show that this slope current is an extension of the Antarctic Slope Current that has crossed the South Scotia Ridge west of Orkney Plateau. On monthly to interannual time scales the density of the slope current is negatively correlated (r > 0.6 with a significance of over 95%) with eastward wind stress over the northern Weddell Sea, but lagging it by 6–13 months. This relationship holds in both the high temporal resolution bottom lander time series and the 20+ year annual hydrographic occupations and agrees with Weddell Sea export variability observed further east. We compare several alternative hypotheses for this wind stress/export relationship and find that it is most consistent with wind-driven acceleration of the gyre boundary current, possibly modulated by eddy dynamics, and represents a mechanism by which climatic perturbations can be rapidly transmitted as fluctuations in the supply of intermediate-level waters to lower latitudes.

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Weddell_Sea_Slope_Export_accepted.pdf - Accepted Manuscript
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Meijers_et_al-2016-Journal_of_Geophysical_Research__Oceans.pdf - Version of Record
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More information

Accepted/In Press date: 15 September 2016
e-pub ahead of print date: 17 October 2016
Published date: October 2016
Keywords: Weddell Sea, Slope Current, Antarctic Circumpolar Current
Organisations: Ocean and Earth Science, Physical Oceanography, Marine Physics and Ocean Climate

Identifiers

Local EPrints ID: 405805
URI: http://eprints.soton.ac.uk/id/eprint/405805
PURE UUID: da18b597-8bc3-4082-b3b2-c254bffbee52

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Date deposited: 10 Feb 2017 16:03
Last modified: 08 Jan 2022 06:39

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Contributors

Author: A.J.S Meijers
Author: M.P . Meredith
Author: E.P. Abrahamsen
Author: M.A.M. Maqueda
Author: D.C. Jones

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