On the Leeuwin Current System and Its Linkage to Zonal Flows in the South Indian Ocean as Inferred from a Gridded Hydrography
AbstractThe 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 1/8 deg) 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; 1 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 22degS to 1.5 Sv at 34degS) This LC transport is significantly smaller than previous.