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The successful launch of the Jason-2 altimetry satellite complements the constellation of satellites currently in flight. Overview of current and future altimetry applications.

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Thanks to satellite oceanography, mankind is just about beginning to understand the ocean machine, which has a decisive influence on the environment and the climate. The successful launch, on 20th June 2008, of the Jason-2 altimetry satellite complements the constellation of satellites currently in flight, initiated with ERS-1 and Topex/Poseidon in 1992 and then continued with Jason-1 and Envisat in 2002. Jason-2 comes at a perfect time to combine all these data and provide a resolution that is ideal for mapping the ocean, and for modelling smaller-scale phenomena. For the first time, an altimetry satellite will have a profile of the altitudes of the areas flown over, in its embedded memory. Coupled with the Doris location system, Jason-2's altimeter is able to anticipate topographical contrasts and calculate the return time of the radar echo more accurately, defining land/water transitions more rapidly and thus yielding greater amounts of data near coasts or over continental waters.

This column on "Altimetry applications in videos" produced by Cnes on the occasion of the Jason-2 launch, traces the many fields where this technique is involved: <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>El Niño, the mean sea level (<link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>its rising, <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>Venice), the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>ocean circulation, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>Mediterranean Sea, <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>operational oceanography, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>oil spills, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>maritime transport and safety, <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>biology, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>fishing management, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>tsunamis, the <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>monitoring hurricanes, hydrology (<link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>Aral Sea, <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>lake Chad, <link http: www.aviso.oceanobs.com en news-storage news-detail _top external-link-new-window>rivers).

Tomorrow still other applications will be possible. The physical models of the ocean - temperature, salinity and currents- will be associated with biological models to better simulate the behaviour of living species and practise a sustainable management of marine resources. The sea is also a wide source of a renewable energy. People have long known the hydro-electric potential of the tides, of the swell and of the different currents. Today we are discovering the possibilities of the offshore wind and the ocean geothermal energy. The renewable energy production from the ocean will require huge investments which could be optimized thanks to the knowledge provided by altimetry. Altimetry is destined for having good times ahead.