Five years in orbit for Jason-1

Image of the month - December 2006

Jason-1 (Credits Cnes/Nasa)

Five years ago, on December 7, 2001, Jason-1 (Cnes/Nasa) was put on orbit by a Delta II rocket from the Vandenberg base, in California. This launch marked the end of a story, begun in 1993 with the decision of the mission, and the start of a new one, which is still ongoing.
Since this date, the harvest of results is continue, with in particular:

  • long-term studies (mean sea level measurements, monitoring of phenomena taking place during 10 years or more,...), for which Jason-1 took over from Topex/Poseidon. Those studies also showed phenomena yet unobserved (for example, the warm eddies tendency to go towards the Equators, and of the cold eddies towards the pole; see the Image of the Month of May 2005: Warm and cold eddies part ways)
Map of sea level trends between 1993 and 2005, from Topex/Poseidon and Jason-1, and the variations over this period in four different regions. The available 13 years are not yet sufficient to determine a long-term trend of ocean change. (Credits JPL)

Moreover, during the September 2002-October 2005, the fact that four altimetric satellites were working at the same time (Topex/Poseidon, ERS-2 then Envisat, GFO et Jason-1), on different but complementary orbits, showed the interest of such a constellation for a better space and time coverage (Four satellites to watch over the Mediterranean), including for ocean forecasting accuracy (Several altimetry satellites for ocean forecasts)

Today, several studies are done about data enhancement near the coast (Closer to the coasts). Use of altimetry data to better understand the path of migrating marine animals is beginning (The impact of currents: a long way to paddle home for a green turtle). Applications take advantages of the comparison of the measurements done at the two frequencies available on the altimeter (rain rater, measurements over ice, over solid land...). Altimetric measurements are more and more associated to other data, to better take into account the ocean under all its aspects.

Tomorrow, Jason-2 will take over, with an even better accuracy, especially near the coasts, in partnership with Eumetsat and Noaa in addition to Cnes and Nasa. Continuing this series of measurements is more than ever necessary, with Jason-2, and with other satellites.

See also:

Websites on this subject: