Western Indian Ocean Bleaching Warning

This bleaching alert runs from January to May each year, compiling publicly available information and observations from the field into an accessible document. The maximum sea surface temperatures that cause coral bleaching occur in January in southern Madagascar/central Mozambique and progress through to May in the northern Indian Ocean as the sun moves north.

Some of the publicly available data sets used in analysis of the bleaching warning for the WIO include;

Sea Surface temperature (SST) anomaly: this is produced by subtracting the long-term mean SST (for that location in that time of year) from the current value. A positive anomaly means that the current sea surface temperature is warmer than average, and a negative anomaly means it is cooler than average. SST anomaly product makes it possible to quickly pinpoint regions of elevated SSTs throughout the world oceans.
Source: NOAA Coral Reef Watch

Coral Bleaching Hotspots: highlights regions where the SST is currently warmer than the highest climatological monthly mean SST for that location. The HotSpot value of 1.0 °C is a threshold for thermal stress leading to coral bleaching. To highlight this threshold, HotSpot values below 1.0 °C are shown in purple and HotSpots of 1.0 °C or greater range from yellow to red in the coral bleaching hotspot charts.
Source: NOAA Coral Reef Watch

El Niño Southern Oscillation (ENSO): The biggest player in the game of year-to-year climate variability. Abnormally warm sea surface temperatures (SST) often signal the beginnings of positive SST anomalies over a much larger domain.
Source: NOAA Earth Systems Research Laboratory

Indian Ocean Dipole (IOD): This is a coupled ocean-atmosphere phenomenon which is normally characterized by anomalous cooling of SST in the south-eastern equatorial Indian Ocean and anomalous warming of SST in the western equatorial Indian Ocean.
Source: Japan Agency for Marine Earth Science and Technology

Doldrums: This is a product from NOAA which identifies and tracks regions of sustained low wind speed conditions that may lead to coral bleaching. Wind-driven mixing reduces temperature stress and periods of sustained low wind promote environmental conditions adverse to corals by increasing thermal and/or light stress.
Source: NOAA Coral Reef Watch

Coral bleaching thermal stress outlook: The Bleaching Thermal Stress Outlook is based on sea surface temperature (SST) forecasts from the NOAA Earth System Research Laboratory. In a normal year, the Outlook forecasts no potential for bleaching. When forecast SST exceeds bleaching thresholds over a long enough period to cause bleaching, the outlook maps display the bleaching potential.

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