Satellites & Bleaching

50-km Products Overview

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Intro to Our 50-km Data Products  |  Data Delivery and Formats
Coral Reef Watch products

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 50-km products in the following sections of the tutorial, so don't worry about the details right now. This is only a brief introduction to Coral Reef Watch's heritage suite of 50-km products.

All of the data we provide are based on satellite measurements of sea surface temperature (SST). Our first 50-km data product is simply the SST measured 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 noted previously, 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 product 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 the Degree Heating Week (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 50-km data products 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 50-km products. All of our 50-km products are available on the Coral Reef Watch website, completely free for anyone to use. Of note, the 50-km products discussed in this tutorial are produced in "operational" status, meaning the products are supported and delivered by NOAA/NESDIS on a 24-hour/7-day basis, permitting almost constant global monitoring of environmental conditions that can cause coral bleaching.

**Note: as of February 17, 2015, we are now featuring next-generation, daily 5-km coral bleaching products on the Coral Reef Watch website. We still provide complete access on the website to the heritage suite of operational twice-weekly 50-km products, described in this tutorial, at:**

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