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A continental shelf scale examination of the Leeuwin Current off Western Australia during the austral autumn–winter

Weller, E., Holliday, D., Feng, M., Beckley, L. and Thompson, P. (2011) A continental shelf scale examination of the Leeuwin Current off Western Australia during the austral autumn–winter. Continental Shelf Research, 31 (17). pp. 1858-1868.

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Link to Published Version: http://dx.doi.org/10.1016/j.csr.2011.08.008
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Abstract

A continental shelf scale survey from 22°S to 34°S along the Western Australia coast provides the first detailed synoptic examination of the structure, circulation and modification of the southward flowing Leeuwin Current (LC) during the late austral autumn-early winter (May-June 2007). At lower latitudes (22°S-25°S), the LC was masked within a broad expanse of warm ambient surface water, which extended across the shelf and offshore before becoming constrained at the shelf break and attaining its maximum velocity of ~1.0ms-1 at 28°S. The temperature and salinity signature of the LC experienced substantial modification as it flowed poleward; surface temperature of the LC decreased by ~5.25°C while surface salinity increased by ~0.72, consistent with climatology estimates and smaller (larger) for temperature (salinity) than those found during summer. Subsequently, LC water was denser by ~2σT in the south compared to the north, and the surface mixed layer of the LC revealed only a small deepening trend along its poleward trajectory. Modification of the LC resulted from a combination of mixing due to geostrophic inflow and entrainment of cooler, more saline surrounding subtropical waters, and convective mixing driven by large heat loss to the atmosphere. Air-sea heat fluxes accounted for 50% of the heat lost from the LC in the south, whilst only accounting for 25% in the north, where large geostrophic inflow occurred and the LC displayed its maximum flow. The onshore transport was characterised by distinct jet-like structures, enhanced in the upper 200m of the water column, and the presence of eddies in the vicinity of the shelf break generated offshore transport.

Item Type: Journal Article
Murdoch Affiliation: School of Environmental Science
Publisher: Elsevier BV
Copyright: © 2011 Elsevier Ltd.
URI: http://researchrepository.murdoch.edu.au/id/eprint/5845
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