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TOPEX/Poseidon: Perspectives on an Ocean Planet

- Tides

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tides

Tides are the natural rise and fall of sea level due to pulls of gravity between the Sun, earth and Moon. The orbit of TOPEX/Poseidon was especially chosen to permit the satellite to measure the solar and lunar tides.

A significant accomplishment of TOPEX/Poseidon is that data from the satellite have been used by the Science Team to produce the most accurate global maps of tides. As a result, tides can now be predicted everywhere in the deep ocean with an accuracy of 2 centimeters.

This level of accuracy is necessary to understand many oceanic and geodetic processes: tides are important for navigation especially in coastal regions; tides slow up the rotation of the moon around the earth, and cause the moon to keep the same face toward the earth; the weight of the tides depresses the sea floor, disrupting measurements of gravity on land; and finally, tides change the orbits of artificial satellites, such as the Hubble Space Telescope and TOPEX/Poseidon.

Once TOPEX/Poseidon measurements of sea level have been corrected for the influences of tides, the data are used for the study of ocean circulation.