Stratification, Asymmetries and Impacts on Residual Flows in the Sydney Estuary

Abstract: 

This study focused on isolating and determining the magnitude of different forcing mechanisms (such as tides, winds, river discharges and horizontal salinity gradients) responsible for temporal variations on mixing and stratification conditions in Sydney Estuary. A three-dimensional coastal ocean model was used to reproduce the intra-tidal and spring-neap variations of current velocity, salinity and residual currents in the water column and these data were compared with field measurements where available. River discharge and A horizontal salinity gradient were found to induce prolonged stratification during neap tides and tidal straining occurred with stronger stratification during ebb tides. Asymmetries in turbulent mixing and stratification during tidal cycles induced by two mechanisms:  tidal oscillations over variable bathymetry and buoyancy inflow with a longitudinal salinity gradient, allowed for the development of residual flow.