THE LOW-FREQUENCY CIRCULATION IN AND AROUND BASS STRAIT - A NUMERICALSTUDY

A barotropic finite difference model is used to examine the scattering and generation of continental shelf waves (CSWs) for the Bass Strait region. For a rectangular bathymetric model, results are found to comp are well with analytic solutions and show that any short CSWs generate d are insignificant. Since short CSWs do not generally exist in a stra tified ocean, the model results represent a barotropic analog for the scattering of coastal-trapped waves. Using a realistic bathymetry, a 1 0 day period mode 1 CSW incident from the Great Australian Bight was f ound to scatter 50% of its energy into the western strait mouth and no rthwards along the East Australian shelf. The flux and circulation dri ven by the 10 cm amplitude incident CSW was also found to be similar t o that driven by a similarly periodic 0.1 Pascal zonal wind stress. Th e low-frequency circulation was also simulated for a 55 day period in 1984 by forcing the model with observed local winds and adjusted sea-l evel from Portland: variations in the latter were assumed to arise fro m a mode 1 CSW that is incident from the Great Bight. The results comp are well with extant current and sea-level data from within the strait and in agreement with the results of ACE, a net flux of 2 x 10(8) W w as computed for the East Australian shelf.