THE PREDICTION OF WIND-FORCED CURRENTS AND SEA-LEVEL ON THE SOUTHEASTAUSTRALIAN CONTINENTAL-SHELF

The Australian Coastal Experiment (ACE) in 1983-84 demonstrated the fe asibility of using wind-forced coastal-trapped wave (CTW) theory to pr edict low-frequency alongshore currents and sea levels on the east Aus tralian continental shelf. Moreover, it emphasized the importance of u pstream boundary conditions for the CTW model to be of practical use. In ACE, the first three CTW modes at the upstream boundary of the mode l were obtained via an array of current meters across the continental shelf and slope. An alternative approach when such arrays are not avai lable is to use the close relationship between the observed CTW modes in the southern ACE region and coastal sea level (or alongshore wind s tress) in eastern Bass Strait to derive proxies for the modes from tho se readily obtainable variables. A CTW model that uses these revised m odes as an upstream boundary condition is run for the ACE period, and predictions of alongshore current and sea level in the vicinity of Syd ney compared with those from the standard model, as well as with the o bserved data. The respective hindcasts are qualitatively similar, thou gh the revised model gives amplitudes that are about 10%-15% smaller t han those from the standard model. An independent test of the scheme, made by running the revised model for the December 1984-April 1985 per iod, indicates predictions are in good agreement with the observed alo ngshore current record at a nearshore site some 400 km north of the mo del's upstream boundary.