This real-time dataset is a global satellite product showing accumulated thermal stress to coral reefs that can lead to bleaching; updated daily.
The NOAA Coral Reef Watch daily 5-km satellite Degree Heating Week (DHW) product monitors accumulated thermal stress that can lead to coral bleaching and subsequent death. The product's color scale ranges from 0 to 20℃-weeks. It is directly related to the timing and intensity of coral bleaching.
The DHW accumulates daily Coral Bleaching HotSpot values, for the previous 12-weeks, that meet or exceed 1℃ above the maximum monthly mean (MMM) temperataure (or the warmest of the twelve monthly mean temperatures in the climatology) for all known coral reef locations worldwide. As an example, for a coral reef area where the HotSpot was either 1℃ above the MMM for two weeks OR 2 ℃ above the MMM for one week during the preceding 12-week period, its DHW value would be the same, 2℃-weeks.
Significant coral bleaching usually occurs when the DHW value reaches 4℃-weeks. By the time the DHW reaches 8℃-weeks, widespread bleaching is likely and significant mortality can be expected.
The NOAA Coral Reef Watch program's satellite data provide current reef environmental conditions to quickly identify areas at risk for coral bleaching, a phenomenon where corals lose the symbiotic algae that give them their distinctive colors. If a coral is severely bleached, disease, partial mortality and/or death become likely.
Continuous monitoring of sea surface temperature (SST) at global scales provides resource managers, researchers and other stakeholders with tools to understand and better manage the complex interactions on a reef that lead to coral bleaching. When bleaching conditions occur, NOAA Coral Reef Watch's satellite (and modeled) tools are used to trigger bleaching response plans and support appropriate management decisions.
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