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Coral Reef Watch Satellite Bleaching Alert System


Current list of available reef sites

The NOAA Coral Reef Watch (CRW) Satellite Bleaching Alert (SBA) system is an automated, free e-mail system designed to monitor and alert users to thermal stress conducive to coral bleaching, as detected by the CRW global satellite near-real-time monitoring products. It automatically delivers up-to-date information on the change of Bleaching Alert status of local coral reef environments to reef managers, scientists, and other interested individuals. The SBA is a convenient data delivery system that allows critical information about coral bleaching thermal stress to reach a user's e-mail account immediately, without the user having to manually check the CRW website for updated information. The SBA was launched in July 2005 as a companion, operational product for the 24 operational Virtual Stations. In March 2013, this system was expanded to include 227 Virtual Stations.

An automated e-mail is sent to a subscriber when the level of coral bleaching thermal stress changes (see table below) at the Virtual Stations to which the user subscribes. The thermal stress status is evaluated twice-weekly. A sample of the SBA message can be viewed here. All of the information that is normally found on the Coral Bleaching Virtual Stations webpage is included in the SBA emails. Also included are internet links to time series graphs and global/regional images, and previous bleaching alert levels experienced at the affected Station. The bleaching thermal stress levels are defined in the table below based on the current values on the NOAA CRW Coral Bleaching HotSpot and Degree Heating Weeks (DHW) products.

Stress Level
    Potential Bleaching Intensity
No Stress
Bleaching Watch
Bleaching Warning
Bleaching Alert Level 1
Bleaching Alert Level 2
HotSpot <= 0
0 < HotSpot < 1
1 <= HotSpot and 0 < DHW < 4
1 <= HotSpot and 4 <= DHW < 8
1 <= HotSpot and 8 <= DHW
No Bleaching
Possible Bleaching
Bleaching Likely
Mortality Likely

To receive automated e-mail alerts for any of the 227 Virtual Stations, follow the link "Subscribe to Satellite Bleaching Alerts" at the top of this page. Once a subscription is added to the e-mail alert system, a user can view and alter selection(s) or unsubscribe from the e-mail list through the same subscription portal.

If you subscribed to the previous operational SBA system with 24 Virtual Stations, these stations still remain in the current list of 227 Virtual Stations, but the names are slightly different. Changes to the previous 24 Virtual Station names can be viewed here.

If at any time you would like to unsubscribe from the automated e-mail alert service, please visit the unsubscription page.

Detailed Description of Satellite Bleaching Alert System
CRW Operational Twice-weekly 50 km Product Suite

Reports of coral bleaching (including observations of no bleaching) are greatly appreciated. Bleaching observations can be entered into the NOAA/ReefBase collaborative online bleaching report form.

Should you have any questions or feedback on the Satellite Bleaching Alert (SBA) system, please e-mail

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Last Modified October 29, 2013 (kh)