Organization: National Aeronautics and Space Administration (NASA)

Research Title: TOPEX/POSEIDON Ocean Topography Experiment

Funding Level (millions of dollars):

FY94 33.7
FY95 31.2
FY96 17.3

Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Subcommittee (100%)
(b) Environmental Issue: Natural variability (75%) Global change: exploratory research with broad focus not primarily in another category (25%)
(c) Research Activity: System structure and function: Observation (100%);

Organizational Component:
Data and Information Systems Division
Office of Mission to Planet Earth
NASA Headquarters
Washington, DC 20546

Point of Contact:
George Komar
Phone: 202-358-0246

Research Goals:
The oceans are the thermal memory of the climate system. Our climate would be dramatically cooler if heat were not transported by the ocean from the tropics to polar latitudes. To understand our climate system, information is needed on the large- scale ocean circulation and how it changes with time. TOPEX/POSEIDON, which measures changes in sea level height, a direct measure of the ocean circulation, is designed to provide data critical to improving our understanding of the role that the ocean play in climate change. In addition, global sea level rise is an anticipate response to greenhouse gas induced global warming. With careful analysis of the TOPEX/POSEIDON data, it is hoped that it will be possible to precisely measure the anticipated several millimeter per year change in sea level.

Research Description:
Radar altimeters onboard TOPEX/POSEIDON are measuring sea-surface height with an unprecedented accuracy of 3 cm from which the large-scale ocean circulation can be calculated. Researchers will use these data to develop models for extended weather and climate prediction, global ocean tides, local and global sea level sea surface height variations, and the study of the interaction between the Earth's atmosphere. A diverse set of global and regional studies are currently underway by the NASA/CNES science team to analyze the first two years of data from the mission. One striking example is the observation of Kelvin waves in the TOPEX/POSEIDON data, which are associated with the onset of the El Niño phenomena.

Program Interfaces:
The Physical Oceanography Program of the Physical Climate Branch is an integral part of Mission to Planet Earth program which is addressing climate change issues through a coordinated effort with other federal agencies in the US. Global Change Research Program (USGCRP) and internationally through bilateral and multilateral agreements with the space agencies of other countries and agencies such as the U.N. World meteorological Organization, World Climate Research program (WCRP). Specifically, this mission is part of the NASA contribution to the World Ocean Circulation Experiment (WOCE) and the Tropical Ocean Global Atmosphere (TOGA) programs.

Program Milestones:
Selection of science team 1987. Launched August 1992. Extended mission begins August 1995.

Policy Payoffs:
These data can be used to observe interannual variability such as El Niño. Improved predictions resulting from incorporating these data into predictive models could potentially save billions of dollars in property and resource loss. In addition, it is hoped that in the future these data can be used for observing changes in global sea level, which could have a significant impact on coastal planning and development.