Fluid transport through Bass Strait

Abstract

The flux of water through Bass Strait was measured with two sections of current meter moorings placed in the west of Bass Strait between Cape Otway and King Island, and King Island and Hunter Island, in the autumn and winter of 1984. The flux was found to be highly correlated with the local wind stress and the time gauges on the northern boundary. Mean flux over the period of the experiment was 0.49 Sv from west to east, with a maximum of +3.05 Sv and a minimum of –0.8 Sv. Much of this flux occurred in surges lasting 2–3 days following the passage of atmospheric cold fronts across the region. The variations in flux may be monitored by a single tide gauge on the eastern Victorian coast, at least in winter. From dynamical considerations it is inferred from the available data that the through-flow is forced by a combination of forcing to the west of Bass Strait and wind stress within Bass Strait in the approximate ratio of 3:1. It seems probable that these surges are the principal cause of the coastally trapped waves observed in the Australian Coastal Experiment of 1983–1984 ( H. J. Freeland et al. (1986) The Australian Coastal Experiment: A search for coastal trapped waves. Journal of Physical Oceanography, 13, 1230–1249). It appears that the geometry of Bass Strait causes singularities in linear coastally trapped wave theory in the south-west and north-east corners, and it is probable that this phenomenon is manifested in the stronger currents observed in the south-west than at the other stations further north.