Measuring Sea Surface Temperature

SST January 2006 average
Figure 1: Average Sea Surface Temperture in January 2006
(Image: University of Leicester)

Sea surface temperature (SST) is one of the parameters we need to measure as accurately as possible, so that we can monitor how the climate is changing and provide data that will help scientists predict how the climate is likely to change in the future.

Until the advent of satellite measurements, all SST measurements were taken in situ, that is by throwing buckets over the side of ships and measuring the temperature with a thermometer, or electronically from buoys either floating freely in the oceans or moored to the ocean bottom.

As you can imagine the SST measurements were patchy in some areas, non-existent in others and variable in accuracy. However, satellite instruments can now give us consistently accurate measurements of SST, which supplement the measurements that continue to be measured from buoys.

Figure 1 shows the average SST as measured by the UK-designed Advanced Along-Track Scanning Radiometer (AATSR) in January 2006. The temperature is measured in Kelvin (1 Kelvin = 1 degree Celsius and 273K = 0 degree C).

The highest temperatures shown in Figure 1 occur in the southern hemisphere tropical regions, as the tilt of the Earth's axis causes the Sun to be overhead these regions around January.

You can the compare the average SSTs in January with those from other times of the year. Just click on the figure you are interested in and a new window will pop up with the new image:

Figure 2 shows the average SST as measured by the AATSR in April 2006. In this image the Indian Ocean, the Atlantic waters off Brazil, the equatorial Pacific and the Pacific coast off Central America are all warming up. The waters around the UK are still quite cold.

Figure 3 shows the average SST as measured by the AATSR in July 2006. The highest temperatures are now in the northern hemisphere tropical regions. The Pacific waters off China are warmer. It is also relatively hot in the Red Sea, the Persian Gulf and the Gulf of California. The warming waters in the northern parts of the oceans provide the energy for hurricanes and typhoons. The waters around the UK are warmer and the Baltic, Mediterranean, Caspian and Black Seas are all warming up as well.

Figure 4 shows the average SST as measured by the AATSR in October 2006. The Red Sea and the Persian Gulf are the warmest areas of water. In the higher latitudes of the northern hemisphere, including the UK, the water is cooling. The Antarctic Ocean contains the most extensive cold water.

A good place to find out more about Sea Surface Temperature measurements is the UK Met Office.

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