TOPEX/POSEIDON Precise Orbit Ephemerides

The oceans play a fundamental role in maintaining a life-sustaining
climate on Earth by transporting an enormous amount of heat through
their large scale circulation systems. Understanding the role that the
ocean circulation plays in climate change is the main goal of the
TOPEX/POSEIDON mission, a cooperative project between the United
States' National Aeronautics and Space Administration (NASA) and the
French Space Agency, Centre National d'Etudes Spatiales (CNES).
TOPEX/POSEIDON uses advanced satellite radar altimetry, a microwave
radiometer and very precise tracking systems (DORIS, laser
retroreflector and an experimental GPS receiver) to make very precise
and accurate observations of sea level -altimeter accuracy better than
2 centimeters, orbit accuracy better than 3 centimeters- for three
(nominally) to five (expected) years. The orbit, satellite bus and
payload instruments are optimized to measure sea level, to map
basin-wide variations of currents, and to monitor the effects of the
currents such as the Gulf Stream, on global climate change. Altimeter
measurements also allow scientists to study ocean tides and waves,
marine geophysics and winds. Launched by Ariane on August 10, 1992,
TOPEX/POSEIDON is a core element of the international World Ocean
Circulation Experiment (WOCE) and Tropical Ocean and Global Atmosphere
(TOGA) measurement programs. Analysis of the satellite altimetry data,
together with WOCE and TOGA ocean measurements, yields major advances
in our quantitative understanding of the ocean circulation and its
climate. TOPEX/POSEIDON lays the foundation for long term ocean
monitoring from space.

They are TOPEX/POSEIDON Precise Orbit Ephemerides (POEs) produced by
CNES and they are TOPEX/POSEIDON Precise Orbit Ephemerides (POEs)
produced by NASA. Both products are re-formatted and made available -
one file per entity - to users by AVISO and JPL/PODAAC. The POEs are
distributed on CD-ROMs (ISO 9660). Each CD-ROM contains two ten-day
repeat-cycles of data : Merged GDRs, crossover files and CNES and NASA
orbit ephemerides. They are swath data and no images. Waveform data
are not included in the GDR-Ms.

CD-ROMs are being produced and are available as the data are
processed. They are disseminated systematically to TOPEX/POSEIDON
Principal Investigators and Co-Investigators. User handbooks - one for
the CD-ROM, one for the data products - are distributed with the first
CD-ROM. For more information, you can connect to the AVISO World Wide
Web server or contact either one of the investigators, the AVISO data
center or the AVISO technical contact.