(Great Barrier Reef)
(Click on the images to see their full-sized images.)
Maps show the period of time, on average, between repeat occurrences of each thermal stress level. Where no event has been observed for a particular threshold, the pixel is colored blue. For each sub-region, the median return periods for all contained pixels is also displayed (n.b., the median is the middle value when all values are arranged in order).
Historical satellite-derived sea surface temperature (SST) data were sourced from the NOAA/NASA AVHRR Pathfinder SST Project for 1985-2009. Return periods are calculated using 50 km (0.5-degree) SST values, matching the resolution of Coral Reef Watch's near-real-time coral bleaching monitoring. Reef-containing pixels are defined using reef location map from ReefBase.
This product will be updated on an approximately annual basis as new AVHRR Pathfinder data become available.