50-km Bleaching Alert Area
Data Formats Available
All of our
satellite data products are available on Google Earth.
and downloadable animated GIF files from OSPO.
HDF data files
Raw data in
Hierarchical Data Format (HDF), with free NOAA viewing software.
The NOAA Coral Reef Watch (CRW) twice-weekly 50-km satellite Coral Bleaching
Alert Area product presented here outlines the areas where bleaching thermal
stress currently reaches various bleaching stress levels, based on our
satellite sea surface temperature monitoring. The bleaching thermal stress
levels are defined in the table below based on the current values of the NOAA
CRW coral bleaching
Degree Heating Week (DHW)
Potential Bleaching Intensity
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
Please note that locations with a current status of Bleaching Watch or No Stress
recently may have been exposed to thermal stress. Although these two levels
classify the current thermal stress condition, they do not take into account
the recent stress history that is measured by the
Degree Heating Week product.
When the instantaneous thermal stress during the
current twice-weekly time period drops to a Bleaching Watch or No Stress level
from a previously higher level, this product does not present any information
on accumulated thermal stress during the past 12 weeks up to the previous
twice-weekly period. Hence, a coral reef that is at Alert Level 2 one week may drop
to Bleaching Watch or No Stress the following week. Please refer to CRW's
Degree Heating Week (DHW) product for information on the accumulated thermal stress during the
past 12 weeks.
This product is updated twice-weekly on every Monday morning and Thursday morning,
U.S. Eastern Time. CRW's
methodology web page
and Liu et al. 2013
provide detailed information about CRW products.
NOAA Coral Reef Watch (CRW)
has been providing near-real-time global 50-km (0.5 by 0.5-degree spatial
resolution precisely) satellite monitoring of thermal stress that causes
mass coral bleaching
to the U.S. and international coral reef communities since 1997. Our operational
monitoring products, including
Degree Heating Week (DHW),
derived from our operational
measured by POES
have been very successful in detecting and monitoring the thermal stress that
causes coral bleaching.
Product description in the tutorial.
Technical details on the methodology page and in
Liu et al. 2013.