The Vertical Structure of Currents on the North West Shelf of Australia at Subtidal Frequencies

Abstract

Abstract An EOF analysis of current meter data collected on the North West Shelf of Australia (NWS) suggested that the major part of the low-frequency (subinertial) circulation on the shelf was wind force. The circulation appeared to be dominantly barotropic, but significant variations in the flow with depth were observed. In this paper, the vertical structure of the currents on the NWS is investigated using a rotary EOF analysis of the vertical currents. Use analysis is performed in the frequency domain over a frequency range of 0.03 to 0.78 cpd including the local inertial frequency of 0.69 cpd. The anticlockwise (cum sole) EOFs are found to be significantly coherent with the wind stress in the four frequency bands considered in the analysis, whereas significant coherences occurred in only two of the clockwise bands. To study the origin of the vertical structure in the currents, the observations are compared to the results of a model of the frictional boundary layers. The model incorporates surface and ...