Observations and simulations of a transient shelfbreak front over the narrow shelf at Sydney, southeastern Australia

Abstract

Hydrographic and ADCP velocity measurements of a transient shelfbreak front over the narrow New South Wales shelf at Sydney, southeastern Australia, are presented. These measurements represent the first high-resolution data set of observations of such an event over the Sydney shelf. The observations are also significant since few comprehensive measurements of shelfbreak fronts over narrow shelves have been acquired. The particular roles of the processes that led to the formation of the front could not be conclusively determined from the observations alone since both a strong local wind event and an intrusion of a meso-scale East Australian Current (EAC) eddy occurred during the formation period. A numerical model was used to simulate the response of the shelf to an idealised meso-scale EAC eddy, represented by an alongslope baroclinic current, and a local downwelling favourable wind event. The simulations suggest that shelfbreak fronts can be formed under the concurrent action of an alongslope jet and downwelling favourable local winds.