The Australian Coastal Experiment: A Search for Coastal-Trapped Waves

Abstract

The Australian Coastal Experiment (ACE) was conducted in the coastal waters of New South Wales from September 1983 to 1984. The data obtained allow a detailed examination of the dynamics of flow on the continental shelf and slope and in particular allow a description of coastal trapped wave modes propagating within the coastal waveguide. The trapped-wave signal is contaminated by energy from the East Australia current eddies approaching the continental slope. However, the data do allow a clear separation of the first three coastal trapped wave modes over the range of frequencies appropriate to the weather forcing band. Through that frequency range the phase speed is computed and an empirical dispersion relation determined for each mode. The empirical dispersion relations compare well with the theoretical relations indicating that a large fraction of the variance in current velocities on the continental shelf can be accounted for by coastal trapped wave theory. Wind forcing of trapped waves is also considered and evidence presented that in the ACE area the motions are dominated by the propagation of free waves through the arrays.