The NOAA Coral Reef Watch (CRW) daily 5-km satellite Bleaching Alert Area (7-day maximum) 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.

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

The coral bleaching thermal stress levels of the daily 5-km Bleaching Alert Area (7-day maximum) product are defined in the table below and are based on the current values of CRW's 5-km Coral Bleaching HotSpot and Degree Heating Week (DHW) products.

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 5-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 5-km DHW product for information on the accumulated thermal stress during the past 12 weeks.

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