NOAA Coral Reef Watch will discontinue all operational twice-weekly 50km satellite coral bleaching heat stress monitoring products in April 2020.

These products are being replaced with higher resolution daily 5km satellite products.

Archived 50km data and images will still be available at If you need any assistance, please contact


50-km Virtual Stations

Operational Virtual Stations System (227 Stations)

Google Maps Interface
images 50-km Regional Virtual Stations
Access to the Google Maps page zoomed in to regions of interest.
text summary All 50-km stations and products
Virtual Stations list, with links to time series graphs and data.
text summary Current Status Summary
Text file that lists the current alerts and heat stress status for all 50-km Virtual Stations.
text summary 50-km Station Locations
Text file that gives the latitude and longitude of each station.
e-mail alerts E-mail Alerts (5-km products)
Sign up online for free Satellite Bleaching Alert e-mails (now for the 5-km product suite) that warn of bleaching conditions.

(More stations may be added based on user requests.)

Along with the global data that Coral Reef Watch (CRW) offers, we also focus in on some representative coral reef locations around the world. We call these "Virtual Stations". A Virtual Station is like having a temperature sensor in the water next to a reef, but it is completely based on satellite remote sensing measurements. Users can access time-series graphs and data at 50-km resolution for each Station and sign up for free automated e-mails that alert subscribers when conditions are conducive to coral bleaching. All of these products are updated twice a week.

CRW released its first 24 50-km Virtual Stations around the world as an experimental system in 2000; that system became operational in 2003, ensuring support and delivery of the 24 50-km Virtual Stations by NOAA on a 24-hour/7-day basis. On March 14, 2013, CRW upgraded and expanded its Operational Virtual Stations System to include 227 50-km Virtual Stations. Those 227 50-km Stations were initially developed as an experimental system in April 2011. The original 24 50-km Stations still remain in the 227-Station system, but some of their names have been slightly changed. Changes to the previous 24 Virtual Station names can be viewed here.

The automated operational Satellite Bleaching Alert (SBA) e-mail system is part of CRW's Operational Virtual Stations System. The first operational SBA system was launched in July 2005 as a companion to the 24 50-km Virtual Stations. On March 14, 2013, CRW upgraded and expanded the SBA system to include 227 50-km Virtual Stations. A sample of the SBA message can be viewed here. Details on the SBA e-mail system and how to subscribe to free e-mail alerts can be accessed here.

Product description in the tutorial.
Technical details on the methodology page and in Liu et al. 2013.