Two new data sets from the U.S. Navy's Geodetic Satellite (Geosat) have been produced by the National Oceanic and Atmospheric Administration's (NOAA's) National Ocean Service. Both were derived principally from classified data collected during the 18-month geodetic mission (April 1985–September 1986). Designed and built by the Johns Hopkins University Applied Physics Laboratory, the Geosat radar altimeter measured global sea level with a precision of 3 cm.
The first data set consists of approximately 44-million crossover differences (sea-level differences at ground track intersections). These include the initial 18-month period and the first year of the subsequent exact repeat mission, enabling computation of the continuous 30-month sea level time series spanning the two missions. Thirty-six 6250-bpi magnetic tapes organized in 18 ocean regions document the Geosat crossover differences.