CRW's twice-weekly 50 km products will update around 2 pm on Mondays and Thursdays (U.S. Eastern Time)
starting from 1 February 2016, using a new 50 km SST analysis.
Click here to see details.
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 NOAA/NESDIS' Office of Satellite and Product Operations (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 Bleaching
Alert Area product presented here outlines the areas where coral bleaching thermal
stress currently reaches various bleaching stress levels, based on our
satellite sea surface temperature (SST) monitoring. The coral bleaching thermal stress
levels are defined in the table below and are based on the current values of the NOAA
CRW operational 50-km
Coral Bleaching HotSpot and
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
50-km DHW 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
50-km 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.
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 50-km
monitoring products, including
Coral Bleaching HotSpot and
derived from our operational
measured by POES
have been very successful in detecting and monitoring the thermal stress that
causes coral bleaching.
Additional description in the 50-km products tutorial.
Technical details on the methodology page and in
Liu et al. 2013.