Synoptic views of mean currents over central GBR for 100 days from 12 April 1981. The model was forced by wind, tidal elevation and the regional sea level gradients due to the influence of the East Australian Current. Modelling and field data show that this inflow generates a longshore circulation on the GBR shelf, with resulting longshore currents flowing northward and southward from the bifurcation point. This longshore current is modulated by the wind and by the tides, which can deflect the mean current away from areas of high reef density and generate localised areas of outflows from the GBR shelf to the Coral Sea. The oceanic inflow may also protect coral reefs by preventing river plumes from spreading onto the outer shelf, and it makes it possible for upwelled water to spread quickly over the GBR shelf.
Blue areas indicate water of oceanic origin with low chlorophyll concentrations.
The solid black contour line delineates waters of coastal and oceanic origin. Black areas are land or cloud. The model domain of the present study is indicated by the enclosed rectangle. The image was received and processed by the Australian Institute of Marine Science, courtesy of Orbimage.