SATELLITE-OBSERVATIONS OF CIRCULATION IN THE SOUTHERN GREAT-BARRIER-REEF, AUSTRALIA

Twenty-one NOAA-9 AVHRR satellite images of the southern Great Barrier Reef, spanning the period from June 1986 to September 1988, were exam ined for sea surface temperature patterns in order to trace circulatio n within this bathymetrically complex area. Our findings are in genera l agreement with the few field studies of this region. The East Austra lian Current tended to flow outside the reefs along the shelf break un til it entered the Capricorn Channel, where it either meandered westwa rd along the narrowing shelf, adhering closely to the slope contours, or flowed directly southward. It then impinged upon the shelf break, n ear Fraser Island, where it bifurcated to produce a southward continua tion of the current, and a cyclonic eddy within the Capricorn Channel. Cool water, which commonly occurred over the shelf between Fraser Isl and and Cape Clinton, has probable significance for biological product ion within the adjacent Capricorn/Bunker Reefs of the Great Barrier Re ef Marine Park. Interpreted as a response to upwelling, this cool wate r may be the result of. 1. the combined effect of tidal pumping and co astal trapped waves; 2. effects of the longshore wind component; or 3. topographically-induced upwelling of slope waters due to flow of the East Australian Current along the continental shelf break. The evidenc e for each of these possible factors is discussed.