Satellite altimeter data have been used for the study of equatorially trapped waves since the launch of the Seasat satellite. After Seasat, the U.S. Navy Geodetic Satellite (Geosat) altimeter mission operated for nearly 5 years (from March 1985 to January 1990) and generated—in time span—an unprecedented sea level record from space.
Currently, the U.S.-French TOPEX/Poseidon satellite and the European ERS-1 satellite are operating in their orbits. Both satellites produce more accurate sea level data with improved altimeters on board. Application of satellite altimeter data to the studies of equatorially trapped waves has yielded some new information which has not been available previously [e.g., Miller etal., 1988; Delcroixetal, 1991; White and Tai, 1992].