Life on Earth would be impossible without the oceans. They are a vital element in maintaining the Earth's balance, and cover 70% of the planet's surface.

The turbulent oceans undergo constant variations due to the effect of the wind and air pressure on their surface, the exchange of energy with the land and ice, and the Earth’s rotation. They exchange heat with the atmosphere, thus influencing the planet's climate.

From ancient times, humankind has sought to unveil the mysteries of these phenomena. The earliest sailors amassed information about the currents, winds and temperatures. In the 17th century these practices began to adopt a more scientific approach, with the advent of the first oceanographic expeditions.

Joint French and US development of the experimental Topex/Poseidon programme in 1992 marked a turning point in the study of ocean movements. Altimetric observations made by Topex/Poseidon during the 13 years of its mission life, revealed valuable information about ocean dynamics that could not be obtained using Earth-bound methods.

These analyses of the sea's topography, wave heights and winds made it possible to model oceanic phenomena, leading to major scientific applications. The Jason satellites are now continuing the ocean-observing mission initiated by Topex/Poseidon .

^{Last updated: February 2007}