The charts on this page show the sea surface temperature (SST) time series (solid dark-blue line) and coral bleaching Degree Heating Weeks (DHW) time series (solid red line) over a time period from December 2000 to present for the selected reef site. In each chart, the corresponding thermal condition related to coral bleaching is color-coded and plotted below the time series. The thermal condition is categorized in the five bleaching alert levels defined by Coral Reef Watch's Satellite Bleaching Alert:
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Stress Level No Stress Bleaching Watch Bleaching Warning Bleaching Alert Level 1 Bleaching Alert Level 2 |
Definition HotSpot <= 0 0 < HotSpot < 1 1 <= HotSpot and 0 < DHW < 4 1 <= HotSpot and 4 <= DHW < 8 1 <= HotSpot and 8 <= DHW |
The monthly mean SST climatologies (light-blue crosses) are also plotted to show the "normal" SST condition at the site and the time of its climatologically warmest months which are usually the time of its peak bleaching season.
The time series were extracted from a 50 km satellite water pixel surrounding or close to the selected reef site. A map showing the selected reef site and its satellite pixel is accessible by clicking on the reef name in the title of this page. Bleaching HotSpots are SST anomalies exceeding the maximum monthly mean SST (MMMSST, dashed light-blue line). The MMMSST is the maximum of the twelve monthly mean SST climatology values, and the Coral Bleaching Threshold SST (solid light-blue line) is defined as the MMMSST plus one degree Celsius. Both the MMMSST and Coral Bleaching Threshold SST are location-specific. DHW, in units of degree Celsius-weeks, are the accumulation of bleaching HotSpot anomalies during the previous 12 weeks whenever the SST equals or exceeds the coral bleaching threshold SST at the pixel.
The area below the DHW time series is filled with colors corresponding to the color-coded bleaching alert levels described earlier whenever bleaching related thermal stress is present. At Bleaching Alert Level 1, some bleaching is expected at the site within a few weeks of the alert. An accumulation of 8 DHWs triggers a Bleaching Alert Level 2, at which point widespread bleaching and some coral mortality are likely.
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