Shelf waves generated by a coastal flux

Abstract

Using the zero divergence approximation, we calculate the response of a continental shelf to an oscillating coastal current source which acts through a gap of finite width in the coastline. It is shown that this response consists of a forced oscillation in the neighbourhood of the gap, together with shelf waves appropriate to the shelf on either side. For a shelf of exponential slope similar to that of the East Australian shelf, and a flux through a channel of the dimensions of Bass Strait, the shelf wave response is shown to be qualitaticely similar to the results obtained in the Australian Coastal Experiment. This supports the contention that Bass Strait is a dominant source of shelf waves on the East Australian continental shelf. The 'eddy' mode required to explain the observations may also be attributed to the forced response of the shelf directly off-shore to Bass Strait. This paper also investigates the effect of adopting, in this physical context, simpler boundary conditions at the shelf edge. It is shown that there is some computational simplification, and that the results are largely unaffected by this simplification.