Coral Reef "Degree Heating Weeks"

Most Recent 2 Months Animation
(Western Hemisphere)
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Western Hemisphere Pacific Ocean Eastern Hemisphere
  • 2 Months
  • 4 Months
  • 6 Months
  • 2 Months
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    • Description

    Charts of Degree Heating Weeks (DHWs) are an experimental product, based on satellite data, designed to indicate the length of time that coral reefs experience thermal stress as shown in our Coral Bleaching HotSpot Charts. Presented at this site are animations of our 12 week DHW accumulations created using weekly means and presented for the last several months (2, 4, or 6 months) in both hemispheres.

    One DHW is equivalent to one week of sea surface temperature one degree Celsius warmer than the expected summer-time maximum (Mean Monthly Maximum or MMM). Two DHWs are equivalent to two weeks at one degree above the MMM OR one week of two degrees above the MMM. These charts (produced biweekly at a 50km resolution based on satellite data) are being used to estimate the accumulated thermal stress that often results in bleaching. We recognize that a single stress parameter such as thermal stress may not have the ability to force bleaching events in some areas without other factors (low winds, high solar irradiance, etc.) simultaneously amplifying the thermal stress. In an effort to formulate the full suite of stressors acting in concert to force bleaching, and their thresholds for particular areas, we have implemented a coral bleaching reporting form for your scientific input. Presented at this site are animations of our 12 week DHW accumulations created bi-weekly and presented for the last 2,4,6 months in both hemispheres.

    A coral reef team of the National Environmental Satellite, Data, and Information Service (NESDIS) generates these coral reef bleaching monitoring products. The team comprises scientists from the Marine Applications Science Team (MAST) in Oceanic Research and Applications Division (ORAD) of Office of research and Applications (ORA) and from the Product Systems Branch (PSB) of the Information Processing Division (IPD) of the Office of Satellite Data Processing and Distribution (OSDPD) within NESDIS.


    For more information about satellite coral bleaching studies, please contact
    coralreefwatch@noaa.gov

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    Last revision: 26 July 2006
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