Ocean Currents Offshore from Sydney

All known measurements of ocean currents offshore from Sydney have been collected and analysed. Typically the current speed is in the range 10 to 25 cm/s, with occasional bursts up to 80 cm/s. The current pattern is dominated by long period cycles of about 10 days duration, with diurnal tides and wind making only a small contribution to the measured currents. Three current measurement techniques have been used - drogues, boat-mounted current meters and insitu moored current meters. Similar median currents were predicted with each technique but drogues give the Lagrangian picture, boat-mounted meters provide vertical profiles and moored meters provide long records at a point. The available current records provide a satisfactory basis for predicting the performance and possible impacts of ocean outfalls, and for estimating marine construction conditions. However additional current monitoring for long periods over a large area will be necessary to determine the complete range of processes producing ocean currents offshore from Sydney.