A 10-year climatology of solar radiation for the Great Barrier Reef: implications for recent mass coral bleaching events

A 10-year solar radiation climatology is developed for the Great Barrier Reef region using data from the Geostationary Meteorological Satellite ( GMS). The method uses a look- up table based on the STREAMER radiative transfer model for a tropical atmosphere. One outstanding feature appears in the summer and autumn climatologies which exhibit distinct maxima in the southern end of the study area, between latitudes 18u S and 26u S. There is a small but statistically significant increase in solar radiation over the 10- year study period, with maximum values of just under 1% per decade. The radiation climatology was used to examine previous coral bleaching episodes, and in particular the largest mass bleaching episode that occurred in 2002. Results show that the area of maximum bleaching corresponded closely to the area of maximum solar insolation. Sea surface temperature and solar radiation were used in a variance analysis to discriminate bleached from unbleached reefs. Solar radiation is a better discriminator for inshore areas, but temperature is better at discriminating offshore reefs. Possible reasons for this difference are discussed.