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 examined for sea surface temperature patterns in order to trace circulation within this bathymetrically complex area. Our findings are in general agreement with the few field studies of this region. The East Australian Current tended to flow outside the reefs along the shelf break until it entered the Capricorn Channel, where it either meandered westward along the narrowing shelf, adhering closely to the slope contours, or flowed directly southward. It then impinged upon the shelf break, near Fraser Island, where it bifurcated to produce a southward continuation of the current, and a cyclonic eddy within the Capricorn Channel. Cool water, which commonly occurred over the shelf between Fraser Island and Cape Clinton, has probable significance for biological production within the adjacent Capricorn/Bunker Reefs of the Great Barrier Reef Marine Park. Interpreted as a response to upwelling, this cool water may be the result of: I. the combined effect of tidal pumping and coastal 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 evidence for each of these possible factors is discussed.