Satellites & Bleaching SST Anomaly Product
SST Anomaly Product  |  What is an anomaly?

This chart shows an example of our sea surface temperature anomaly product. Click the image for more information and a larger view of the latest data.

To calculate the SST anomaly, we first needed to know the long-term mean sea surface temperatures. We took almost 10 years of satellite SST measurements, and calculated the mean temperatures in each month for every ocean pixel around the world. These monthly means are called the SST "climatology" and they are available from our website as a separate product. We use them to calculate the twice-weekly SST anomaly, showing where the temperature is different from the normal conditions for that day of the year. An example of our SST anomaly product is shown at the top-right of this page.

Areas in purple to blue mean a negative anomaly; that is, the water temperature is cooler than the mean. Orange to red means a positive anomaly: the temperature is warmer than the mean. The values range from -5 to 5°C. Just like the sea surface temperature product, this SST anomaly has a half-degree spatial resolution (~50km) and it is updated twice each week. We also produce animations of the SST anomaly, for the past 2 to 6 months of data.

The time series graphs for our Virtual Stations also give an indication of whether the SST is above or below the mean, as you will see from this example from the Seychelles:

Remembering that the current SST is shown as the dark blue solid line, you can see that each month's mean temperature for that location is also on the graph as light blue crosses. The months are shown along the bottom of the graph. At this reef location, the mean temperature is highest in April (about 29.5°C) and lowest in July (about 25°C). For these dates during the first half of 2006, you can see that the temperatures in the Seychelles were very close to the long-term mean.

Let's look at what happened in 2005, for that same location (graph on right). Look at the temperature from mid-April until the end of July, and compare to the long-term means in light blue. You can see that the temperature was consistently above the mean for that whole period.

Try our hands-on SST Anomaly exercises to learn more about this product.

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