Jason-1 – Measuring Ocean Topography From Space

Caitlin Dempsey


Jason-1 is a satellite to be jointly operated by NASA and CNES (Centre National d’Etudes Spatiales), the French space agency. Scheduled for launch no earlier than September 15th of this year, Jason-1 will work in tandem with TOPEX/Poseidon, a U.S.-French satellite in operation since 1992. TOPEX/Poseidon marked its ninth anniversary in orbit on August 10th, 2001.

Graphical depiction of Jason-1 in space. Courtesy of NASA/JPL/Caltech.

Once it reaches its final orbit, Jason 1 will assume the flight path of TOPEX/Poseidon, which will move into a parallel orbit. Both satellites will circle Earth every 112 minutes at an altitude of about 1,330 kilometers.

Graphical depiction of the parallel paths the TOPEX/Poseidon and Jason-1 satellites will take. Image courtesy of NASA/JPL/Caltech.

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The focus of both satellites is to take measurements of the topography of the ocean surface. TOPEX/Poseidon measured the ocean’s surface topography to an accuracy of 4.2 centimeters. According to the Jason-1’s fact sheet, the goal is to obtain at least a 2.5 centimeter accuracy surface topography. Ongoing data collected from these satellites is used to map ocean currents, understand ocean circulation, measure changes in sea level and contribute to refining predictive global climate models (GCMs). With data from both TOPEX/Poseidon and Jason-1, researchers hope to provide better forecasting of climatic events such as El Niño.

Sample image from TOPEX/Poseidon showing oceanic temperature patterns. Courtesy of NASA/JPL/Caltech.

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About the author
Caitlin Dempsey
Caitlin Dempsey is the editor of Geography Realm and holds a master's degree in Geography from UCLA as well as a Master of Library and Information Science (MLIS) from SJSU.