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The Antarctic Circumpolar Current between the Falkland Islands and South Georgia

The Antarctic Circumpolar Current between the Falkland Islands and South Georgia
The Antarctic Circumpolar Current between the Falkland Islands and South Georgia
Hydrographic and lowered acoustic Doppler current profiler data along a line from the Falkland Islands to South Georgia via the Maurice Ewing Bank are used to estimate the flow of circumpolar water into the Argentine
Basin, and to study the interaction of the Antarctic Circumpolar Current with the Falkland Plateau.

The estimated net transport of 129 +- 21 Sv (Sv [10^6 m^3 s^-1) across the section is shared between three major current bands. One is associated with the Subantarctic Front (SAF; 52 +- 6 Sv), and the other two with branches of the Polar Front (PF) over the sill of the Falkland Plateau (44 +- 9 Sv) and in the northwestern Georgia Basin (45 +- 9 Sv). The latter includes a local reinforcement (~20 Sv) by a deep anticyclonic recirculation around the Maurice Ewing Bank. While the classical hydrographic signature of the PF stands out in this eastbound branch, it is less distinguishable in the northbound branch over the plateau. Other circulation features are a southward entrainment of diluted North Atlantic Deep Water from the Argentine Basin over the eastern part of the Falkland Plateau, and an abyssal anticyclonic flow in the western Georgia Basin, opposite to what was generally assumed.

The different behavior of the SAF and PF at the Falkland Plateau (no structural modification of the former and partitioning of the latter) is attributed to the PF being deeper than the sill depth on the upstream side of the plateau, unlike the SAF. It is suggested that the partitioning takes place at a location where the 2500-m and 3000-m isobaths diverge at the southern edge of the plateau. The western branch of the PF crosses the plateau at a distance of ~250 km to the east of the SAF. Comparison with a section across the Falkland Current farther downstream shows that its deep part subsequently joins the SAF on the northern side of the plateau where the 2000–3000 m isobaths converge in the steep Falkland Escarpment. The result of this two-stage bathymetric effect is a net transfer of at least 10 Sv from the PF to the SAF at the crossing of the Falkland Plateau.
0022-3670
1914-1931
Arhan, M.
7f2a83d2-e8b8-4e60-a460-2e8190286562
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Heywood, K.J.
4eeebe72-3857-4729-8d6a-7ece46d37cd5
Stevens, D.P.
9b78fd18-9ea2-409d-b78f-61ac70555905
Arhan, M.
7f2a83d2-e8b8-4e60-a460-2e8190286562
Naveira Garabato, A.C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Heywood, K.J.
4eeebe72-3857-4729-8d6a-7ece46d37cd5
Stevens, D.P.
9b78fd18-9ea2-409d-b78f-61ac70555905

Arhan, M., Naveira Garabato, A.C., Heywood, K.J. and Stevens, D.P. (2002) The Antarctic Circumpolar Current between the Falkland Islands and South Georgia. Journal of Physical Oceanography, 32 (6), 1914-1931. (doi:10.1175/1520-0485(2002)032<1914:TACCBT>2.0.CO;2).

Record type: Article

Abstract

Hydrographic and lowered acoustic Doppler current profiler data along a line from the Falkland Islands to South Georgia via the Maurice Ewing Bank are used to estimate the flow of circumpolar water into the Argentine
Basin, and to study the interaction of the Antarctic Circumpolar Current with the Falkland Plateau.

The estimated net transport of 129 +- 21 Sv (Sv [10^6 m^3 s^-1) across the section is shared between three major current bands. One is associated with the Subantarctic Front (SAF; 52 +- 6 Sv), and the other two with branches of the Polar Front (PF) over the sill of the Falkland Plateau (44 +- 9 Sv) and in the northwestern Georgia Basin (45 +- 9 Sv). The latter includes a local reinforcement (~20 Sv) by a deep anticyclonic recirculation around the Maurice Ewing Bank. While the classical hydrographic signature of the PF stands out in this eastbound branch, it is less distinguishable in the northbound branch over the plateau. Other circulation features are a southward entrainment of diluted North Atlantic Deep Water from the Argentine Basin over the eastern part of the Falkland Plateau, and an abyssal anticyclonic flow in the western Georgia Basin, opposite to what was generally assumed.

The different behavior of the SAF and PF at the Falkland Plateau (no structural modification of the former and partitioning of the latter) is attributed to the PF being deeper than the sill depth on the upstream side of the plateau, unlike the SAF. It is suggested that the partitioning takes place at a location where the 2500-m and 3000-m isobaths diverge at the southern edge of the plateau. The western branch of the PF crosses the plateau at a distance of ~250 km to the east of the SAF. Comparison with a section across the Falkland Current farther downstream shows that its deep part subsequently joins the SAF on the northern side of the plateau where the 2000–3000 m isobaths converge in the steep Falkland Escarpment. The result of this two-stage bathymetric effect is a net transfer of at least 10 Sv from the PF to the SAF at the crossing of the Falkland Plateau.

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Published date: 2002

Identifiers

Local EPrints ID: 37552
URI: http://eprints.soton.ac.uk/id/eprint/37552
ISSN: 0022-3670
PURE UUID: b7a95516-1962-413d-b5b4-02f077c35a81

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Date deposited: 24 May 2006
Last modified: 15 Jul 2019 19:04

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