Coral Bleaching

These pages provide information on sea surface temperatures for monitoring coral bleaching events in the Great Barrier Reef, Australia. See latest on the 2016 and 2017 marine heatwave on the reef.

Forecast Skill

Accuracy of model forecasts was assessed to provide a measure of the skill of ACCESS-S1. Retrospective forecasts (hindcasts) of sea surface temperature anomalies (SSTA) were compared to observed SSTA for the same period. SSTAs were calculated for both the model forecasts and observed values by subtracting the climatology from the sea surface temperature (SST) values. The climatology is the monthly mean SST over the period 1990-2012, computed relative to the start month and lead-time for the model. Removing the climatological SST from SST forecast values reduces the effects of any model bias (Stockdale 1997).

The root mean square error (RMSE) was calculated between the model anomalies and observed anomalies. The plot below shows the RMSE of ACCESS-S1 ensemble mean SSTA forecasts for the summer period (January/February/March) for model start dates of 1st October, November, and December over the period 1990-2012. Lower values of RMSE correspond with better model skill. The observed dataset used here for skill calculations is the monthly Reynolds 0.25° SST data analysis, interpolated onto the ocean model grid. The higher skill in the northern parts compared to the southern area is likely due to the larger influence of tropical variability, principally El Niño Southern Oscillation (ENSO).