Satellites & Bleaching Product Overview
Intro to Our Data Products  |  Data Delivery and Formats

Coral Reef Watch uses satellite data to pinpoint areas where high temperatures put corals at risk for bleaching.

You will learn more about each of these products in the following sections of the tutorial, so don’t worry about the details right now. This is only a brief introduction to the whole Coral Reef Watch product suite.

All of the data we provide are based on satellite measurements of sea surface temperature (SST). Our first data product is simply the SST from all around the world. Next, we compare the current temperature with a long-term mean at each location, to calculate an SST anomaly. That tells us where the SST is warmer or cooler than normal today.

As we said earlier, one thing that is stressful to corals is unusually warm temperature. Specifically, scientists found that corals become stressed if the SST is above the highest summertime mean. Our HotSpot data highlight areas where SST is above the mean value you would expect to see in the warmest month of the year. Coral bleaching risk increases even more if the water temperature stays warm for a long time. We total the HotSpot stress over a twelve-week period to calculate Degree Heating Weeks (DHW). It is this DHW product that can readily pinpoint areas around the world where reefs are at risk for coral bleaching.

All of the Coral Reef Watch data are updated twice each week, so you can always see the current conditions around the globe. We call this "near-real-time" monitoring, because there is only a brief time delay with our products. All of our products are available on the web, completely free for anyone to use: coralreefwatch.noaa.gov/satellite.

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