PROGRAM TITLE: TOPEX/Poseidon ACTIVITY STREAM: Integrative Modeling and Prediction SCIENCE ELEMENT:Climate and Hydrologic Systems Global Observing Systems Biogeochemical Dynamics Solar Influences Data and Information Management NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SCIENTIFIC MERIT: TOPEX/Poseidon (launched August 10, 1992), a joint U.S. and French mission, is providing scientists with a detailed, global description of the ocean's topography and currents. Radar altimeters on-board TOPEX/Poseidon are measuring the sea-surface height with an unprecedented accuracy of 3 cm from which can be calculated the speed and direction of ocean currents. Researchers will use these data to develop models for extended weather and climate prediction, global ocean tides, local and global sea-surface variations, and study the interaction between the oceans and the earth's atmosphere. The study of ocean circulation as it is affected by the rotation of the earth and winds which not only drive the ocean surface currents but raise the sea level downwind will provide more insight into the speed and direction of ocean currents. These currents provide global transport for warm and cold water which effect the global climate. An example of this is El Nino which is a transport of warm Asian waters eastward towards South America; the effects of which have been devastating. More reliable prediction of such events can be had through improved knowledge of the ocean circulation. STAKEHOLDERS: TOPEX/Poseidon is a joint U.S. NASA and French CNES mission. It is a core element of the WOCE and TOGA measurement programs. POLICY RELEVANCE: Primary: Climate change and global warming. Seasonal and Interannual Prediction i.e. ,Predicting extreme anomalies such as El Nino. Secondary: International Cooperation Ecological Change and Biodiversity PROGRAM CONTACTS:Michael Van Woert, Program Scientist Office of Mission to Planet Earth NASA Headquarters, Code YS Washington, D.C. 20546 tel: 202-488-5150 fax: 202-479-2613 Patricia K. Liggett, Program Advisor Office of Mission to Planet Earth NASA Headquarters, Code YDO Washington, D.C. 20546 tel: 202-358-0755 fax: 202-358-3098