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On the Leeuwin Current System and its linkage to zonal flows in the South Indian Ocean as inferred from a gridded hydrography

Citation

Furue, R and Guerreiro, K and Phillips, HE and McCreary Jr, JP and Bindoff, NL, On the Leeuwin Current System and its linkage to zonal flows in the South Indian Ocean as inferred from a gridded hydrography, Journal of Physical Oceanography, 47 pp. 583-602. ISSN 0022-3670 (2017) [Refereed Article]


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DOI: doi:10.1175/JPO-D-16-0170.1

Abstract

The Leeuwin Current System (LCS) along the coast of Western Australia consists of the poleward-flowing Leeuwin Current (LC), the equatorward-flowing Leeuwin Undercurrent (LUC), and neighboring flows in the south Indian Ocean (SIO). Using geostrophic currents obtained from a highly resolved (⅛°) hydrographic climatology [CSIRO Atlas of Regional Seas (CARS)], this study describes the spatial structure and annual variability of the LC, LUC, and SIO zonal currents, estimates their transports, and identifies linkages among them. In CARS, the LC is supplied partly by water from the tropics (an annual mean of 0.3 Sv; 17nbsp;Sv ≡ 106 m3 s−1) but mostly by shallow (≲200 m) eastward flows in the SIO (4.7 Sv), and it loses water by downwelling across the bottom of this layer (3.4 Sv). The downwelling is so strong that, despite the large SIO inflow, the horizontal transport of the LC does not much increase to the south (from 0.3 Sv at 22°S to 1.5 Sv at 34°S). This LC transport is significantly smaller than previously reported. The LUC is supplied by water from south of Australia (0.2 Sv), by eastward inflow from the SIO south of 28°S (1.6 Sv), and by the downwelling from the LC (1.6 Sv) and in response strengthens northward, reaching a maximum near 28°S (3.4 Sv). North of 28°S it loses water by outflow into subsurface westward flow (−3.6 Sv between 28° and 22°S) and despite an additional downwelling from the LC (1.9 Sv), it decreases to the north (1.7 Sv at 22°S). The seasonality of the LUC is described for the first time.

Item Details

Item Type:Refereed Article
Keywords:Leeuwin Current, Indian Ocean, downwelling, zonal flows, hydrographic data, observations
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate variability (excl. social impacts)
UTAS Author:Phillips, HE (Associate Professor Helen Phillips)
UTAS Author:Bindoff, NL (Professor Nathan Bindoff)
ID Code:114721
Year Published:2017
Funding Support:Australian Research Council (DP130102088)
Web of Science® Times Cited:18
Deposited By:Oceans and Cryosphere
Deposited On:2017-02-24
Last Modified:2018-05-24
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