TOPEX Outreach
Altimeter Measurements


The state of the art radar altimetery satellite in use today is a joint venture between the National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory (JPL) and the Centre National d'Etudes Spatiales (CNES). The satellite is called TOPEX/POSEIDON and its primary science objective is to improve our understanding of global ocean circulation and determine how this relates to, and interacts with, earth's atmosphere.

The altimeter is to provide levels of precision previously unobtainable in global sea level measurements. Movement of water in the sea on spatial scales exceeding ~30 km and temporal scales exceeding ~1 day are manifested by deflections of the sea surface; that is, by changes in mean sea level associated with the strength and direction ofthe flow. This change in topography varies from the 1 meter increase in mean sea level in 100 km over the Gulf Stream to a 10 cm change over 1000 km over an El Niño event in the tropical Pacific. Given the strength of the sea surface topography signature, one caninfer the magnitude and direction of the oceanic water movement.

Altimeter Calibration


Last Modified: Fri Jan 22, 1999