Laboratory for Satellite Altimetry / Sea level rise

Satellite altimetry web sites

General altimetry information

• CLS has created a tutorial on satellite radar altimetry is available at www.altimetry.info.
• The Jet Propulsion Laboratory's Ocean Surface Topography from Space web site has information about the altimetry missions TOPEX/Poseidon, Jason-1, and Jason-2 as well the science and applications of ocean altimetry.
• AVISO/Altimetry is the French Active Archive Data Center for multi-satellite altimeter missions responsible for post-processing, analyzing, archiving and distributing altimetry data for CNES (Centre National d'Etudes Spatiales), the French Space Agency.

Current missions

• Jason-1 is successor to the TOPEX/Poseidon mission which is designed to ensure the continuity of TOPEX/Poseidon-class measurements. (Launched: December 2001)
• GFO (GEOSAT Follow-On) site maintained by the NOAA Laboratory for Satellite Altimetry. The GFO program is the Navy's initiative to develop an operational series of radar altimeter satellites to maintain continuous ocean observation from the GEOSAT Exact Repeat Orbit. (Launched: 1998)
• ENVISAT (ENVIronment SATellite), the European Space Agency's third major remote sensing effort, a successor of the European Remote-Sensing satellites. It is primarily a research-oriented mission, carrying essentially pre-operational instruments for monitoring and studying the Earth's environment. (Launched: March 2002)
• ERS-2, ESA's second European Remote-Sensing satellite, is largely identical to ERS-1. ERS-2 has been operating without gyroscopes since February 2001, resulting in some degradation of the data provided by the instruments. Because its tape drive failed on June 2003, data are now only available when the satellite is within visibility of a ground station. (Launched: April 1995.)

Future missions

• OSTM/Jason-2, the Ocean Surface Topography Mission on the Jason-2 satellite, is a joint effort by four organizations to continue the TOPEX/Poseidon and Jason-1 sea surface height record. The four mission participants are the U.S. National Oceanic and Atmospheric Administration (NOAA), the U.S. National Aeronautics and Space Administration (NASA), France’s Centre National d’Etudes Spatiales (CNES), and the European Meteorological Satellite Organisation (EUMETSAT). The Jason-2 satellite is scheduled to be launched in June 2008.
• Cryosat-2, an altimetry satellite built by the European Space Agency and dedicated to polar observation, is scheduled to be launched in March 2009. Its primary instrument, a Synthetic Aperture Radar (SAR), will determine variations in the thickness of Earth's continental ice sheets and marine ice cover. In addition to the SAR, Cryosat-2 will carry a nadir-pointing altimeter, which will operate over the ocean for validation purposes. Because the mission will not include a radiometer, direct radiometric corrections will not be possible. Dynamic topography data of medium quality, but from a new orbit, may therefore be available during the three-and-a half-year mission.

Past missions

• Seasat was the first JPL mission to study Earth using imaging radar specifically designed to observe the ocean. (Launched: 1978)
• Geosat (GEOdetic SATellite) was a dedicated US Navy military oceanographic satellite designed to obtain closely spaced, precise mapping of the earth's geoid over the ocean. (Launched: 1985)
• ERS-1 was the first ESA satellite devoted to remote sensing to carry a radar altimeter. ERS-1 had various mission phases using 3-day, 35-day, and 336-day repeat cycles. The 336-day mission (Geodetic Mission) allowed for accurate mapping of the Earth's bathymetry and geoid over the ocean. ERS-1 failed on March 10, 2000. (Launched: July 1991.)
• TOPEX/Poseidon, launched in 1992, was a joint venture between CNES and NASA to map ocean surface topography. While a 3-year prime mission was planned, with a 5-year store of expendables, TOPEX/Poseidon operated for thirteen years. (Launched: 1992)