Satellites have already revolutionized oceanography, and soon they will do the same for hydrology -- the study of water on land. The French/U.S. Surface Water and Ocean Topography (SWOT) mission will be at the forefront, carrying an innovative interferometer dubbed KaRin that marks a break with today's technologies.

dam you notes that these changes show the value the world scientific community places on the ocean altimetry program. "The measurement is so important, and the technology is fully demonstrated," he said. "In the long haul, ocean altimetry is an international commitment."

Abstract

Jason, the successor to the TOPEX/POSEIDON (T/P) mission, has been designed to continue seamlessly the decade-long altimetric sea level record initiated by T/P. Intersatellite calibration has determined the relative bias to an accuracy of 1.6 mm rms. Tide gauge calibration of the T/P record during its original mission shows a drift of −0.1 ± 0.4 mm/year. The tide gauge calibration of 20 months of nominal Jason data indicates a drift of −5.7 ± 1.0 mm/year, which may be attributable to errors in the orbit ephemeris and the Jason Microwave Radiometer. The analysis of T/P and Jason altimeter data over the past decade has resulted in a determination of global mean sea level change of +2.8 ± 0.4 mm/year.