Satellite Remote Sensing of Sea-Surface Temperatures over the Great Barrier Reef.

Coastal areas have great societal and economic importance but present particular problems for satellite remote sensing. Regarding the determination of sea-surface temperatures, microwave radiometry is rendered useless because of the contamination of the measurements by land surface emission through the antenna side lobes, so infrared radiometry has to be used. The challenges concern identifying pixels contaminated by clouds and aerosols, and correcting for the effects of the clear atmosphere. We will present results of a recent study to assess errors and uncertainties in satellite measurements of sea-surface temperature over the Great Barrier Reef, obtained by comparisons between satellite retrievals and in situ measurements at the depth of the corals. Despite the added complications of small scale temperature structure in such a complex coastal environment, and the consequences of a specific distribution of atmospheric properties, the accuracies of the satellite-derived surface temperatures are comparable to what can be achieved in the open ocean. This gives encouragement to the prospect of using satellite data to monitor the thermal structure in a delicate ecosystem that is threatened by natural and anthropogenic stresses. Even though the spatial resolution of currently available data is generally much poorer than that of anticipated sensors, the accuracy of present-day radiometers is limited by factors that will still be present for future missions.