LEEUWIN CURRENT OBSERVATIONS ON THE AUSTRALIAN NORTH-WEST SHELF, MAY-JUNE 1993

Observations of the Leeuwin Current, the poleward Row of warm, low sal inity water off the west coast of Australia, are described from acoust ic Doppler current profiler (ADCP), temperature and salinity (CTD) and moored current meter measurements from the Australian North West Shel f made in May and June 1993. Two cross-shelf and slope transects of AD CP and CTD measurements were completed at latitudes of approximately 1 7 and 19 degrees S. After the removal of the tidal signal, the ADCP me asurements reveal the poleward Rowing Leeuwin Current. The current is broad (250 km at 17 degrees S), deep (at least 440 m) and relatively w eak (typically 0.2 m s(-1)), but the poleward transport of approximate ly 4 x 10(6) m(3) s(-1) is similar to values reported in the literatur e for the more intense part of the Leeuwin Current, between approximat ely 22 and 35 degrees S, where a maximum of approximately 7 x 10(6) m( 3) s(-1) has been observed. There is a significant flow reversal or un dercurrent, of magnitude similar to the poleward transport, at the nor thern transect, but only a weak undercurrent is observed at the 19 deg rees S transect. In the CTD data the current is also seen as a low sal inity core with salinity less than 35.2 but also with patches less tha n 35.0, possibly a result of a series of eddies. A current meter recor d from mid-way along the 19 degrees S transect shows the poleward flow to be relatively persistent over all of May, but slightly stronger to wards the end of May. There is only one significant reversal of flow t owards the equator lasting a few days. Current meter data obtained bet ween August 1983 and March 1985 from 120 m depth in the Timer Sea (app roximately 12 degrees S) are also reported and reveal a weak poleward flow for much of the year and strongest from January to April. For som e of this time (March-April) the poleward Row is supported by the Sout h East Trade winds. However, the poleward current weakens and turns eq uatorward in May/June to flow into the persistent winds from the east. Simultaneous current meter measurements from the shelf at 20 degrees S show similar strength poleward flows from December to March.