Daily Global 5km Satellite Coral Bleaching Heat Stress Alert Area
(Version 3.1, released August 1, 2018, experimental product)
Global Bleaching Alert Area 7-Day Maximum image
Current Daily Variables:  Alert Area (7-day max) 
Regional Images:  45ns | Global | East | West | Pac. | Ind. | S.Atl. | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
Animations (30d):  45ns | Global | East | West | Pac. | Ind. | S.Atl. | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
Animations (90d):  45ns | Global | East | West | Pac. | Ind. | S.Atl. | Coral Triangle [big] | Caribbean [big] | Florida | Hawaii | GBR
Year-to-date Maximum: -----
Year-to-date Minimum: ----- ----- ----- -----
Year-to-date Mean: ----- ----- ----- -----

Click on map above to zoom to small 60 x 40-degree tiles; use drop-down menu below to view larger 60 x 40-degree tiles.     
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Large 60 x 40-degree tiles (by hemisphere, updated daily):  



The NOAA Coral Reef Watch (CRW) daily global 5km satellite Bleaching Alert Area (7-day maximum) product presented here outlines the areas where coral bleaching heat stress currently reaches various levels, based on our satellite sea surface temperature (SST) monitoring.

SST variability is often considerably higher at the much finer 5km spatial and daily temporal resolutions, when compared with CRW's heritage operational twice-weekly 50km (0.5-degree) monitoring product suite. Due to resulting day-to-day fluctuations between stress levels in highly-variable locations, the single-day 5km Bleaching Alert Area product does not consistently and adequately identify potentially harmful heat stress levels, especially with regard to accumulated heat stress impacts. Rather than requiring users to examine the single-day 5km Bleaching Alert Area product over several days, a 7-day maximum Bleaching Alert Area composite product, updated daily, was introduced in the Version 2 product suite and is maintained here in Version 3.1. (Evolution of CRW's daily global 5km product suites can be found here.) This 7-day composite product shows the maximum stress level that a satellite pixel has experienced during the most recent seven (7) consecutive days. Data and images are dated on the last day of the 7-day period. Notably, it is compatible with CRW's operational 50km twice-weekly Bleaching Alert Area product, as the 50km Bleaching Alert Area is based on a half-week (3 or 4 days) composite of 50km SSTs (but with much less SST variability due to its much coarser spatial resolution).

Even though the daily global 5km Bleaching Alert Area (7-day maximum) composite product is presented here, the coral bleaching heat stress levels defined in the table below are for the daily global single-day 5km Bleaching Alert Area product. The heat stress level at a 5km satellite data grid, on any day, is based on CRW's daily global 5km Coral Bleaching HotSpot and Degree Heating Week (DHW) products for that day. The daily global 5km Bleaching Alert Area (7-day maximum) composite product therefore is the maximum value of the seven, consecutive, daily global single-day 5km Bleaching Alert Area values in the data grid that end on the date shown in the image.

Stress Level
    Definition
    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

Note that locations with a current status of Bleaching Watch or No Stress recently may have been exposed to heat stress. While these two levels classify the current heat stress condition, they do not take into account recent stress history that is measured by the daily global 5km DHW. When the instantaneous heat 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 heat 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 daily global 5km DHW product for information on accumulated heat stress during the past 12 weeks.

This product is updated each afternoon at about 13:30 U.S. Eastern Time.

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