The Leeuwin Current

Abstract

The Leeuwin Current is a surface stream of warm, low-salinity tropical water that flows poleward (southward), against the climatological mean equatorward winds, from northwestern Australia to Cape Leeuwin and then eastward towards the Great Australian Bight. It flows principally, but not exclusively, in autumn and winter. In the north, it is broad and shallow (200 km by 50 m), tapering and deepening in the south to a relatively narrow current (less than 100 km wide), with a top speed of 1.8 ms⁻¹ and strong vertical and horizontal shears. There is an equatorward undercurrent below. The warm, low-salinity Leeuwin Current water intrudes between the continent and the southgoing high-salinity flow described by Andrews (1977). As the current approaches Cape Leeuwin, it extends down to about 200 m and is most commonly centered at the shelf edge. After rounding Cape Leeuwin, it spreads onto the shelf and develops seaward offshoots that result in cyclone/anticyclone eddy pairs. A strong poleward geopotential gradient is thought to drive the Leeuwin Current.