Experimental Bleaching Thermal Stress Return Period Products
(Great Barrier Reef)

GBR sample maps GBR sample maps GBR sample maps

color legend of retrun period

(Click on the images to see their full-sized images.)


NOAA Coral Reef Watch is conducting research and development on a new product that estimates the return period of thermal stress linked to mass coral bleaching based on temperature data from the past 25 years. This experimental product is currently provided for the Great Barrier Reef (GBR) region as a pilot project. Once it is evaluated for the GBR region, the algorithm will be applied to other coral reef regions and eventually on a global scale for testing and assessment.

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.