The Earth Observer

July/August 1996, Vol. 8, No. 4

Ocean Winds and Ozone to be Measured by U.S. Instruments Aboard Japanese Earth Observation Satellite

- Douglas Isbell, Headquarters, Washington, DC. (Phone: 202/358-1753)
- Allen Kenitzer, Goddard Space Flight Center, Greenbelt, MD. (Phone: 301/286-8955)
- Mary Hardin, Jet Propulsion Laboratory, Pasadena, CA. (Phone: 818/354-5011)
- Patricia Viets, NOAA/National Environmental Satellite, Data, and Information Service, Suitland, MD. (Phone: 301/457-5005)
- Hideo Hasegawa/Hiroyuki Ikenono, National Space Development Agency of Japan, Tokyo (Phone: 81-3-5470-4127)

Japan's Advanced Earth Observing Satellite (ADEOS) is carrying the NASA Scatterometer (NSCAT) and Total Ozone Mapping Spectrometer (TOMS) instruments, designed to measure global ocean surface winds and atmospheric ozone content, as par t of an international climate change research mission that began with the ADEOS launch from Tanegashima Space Center in Japan on August 17.

"ADEOS is the first in a series of major collaborative efforts between NASA and the National Space Development Agency of Japan in the area of Earth remote sensing," said William Townsend, Acting Associate Administrator for NASA's Office of Mission to Plan et Earth. "As such, it is a superb example of increasing international cooperation between the United States and other spacefaring nations of the world in generating a better understanding of our planet and its complex climate."

Taking advantage of the natural reflection, or "backscattering," of radar pulses by wind-driven ripples in ocean waves, NSCAT will make 190,000 measurements per day of the speed and direction of winds within about 1.5 inches of the ocean surface. These wi nds directly affect the turbulent exchanges of heat, moisture, and greenhouse gases between the atmosphere and the ocean. These air-sea exchanges, in turn, help determine regional weather patterns and shape global climate.

"NASA researchers will use the data to understand the interface between the Earth's two great fluids: the oceans and the atmosphere," said Jim Graf, NSCAT project manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. "Understanding and characterizing this interface is critical to better scientific understanding of global warming, the El Niño phenomenon, and other studies of the Earth as a total system. In addition, seafaring organizations that transport goods and passengers across the oceans can use the data from NSCAT to steer their ships more safely and economically."

Covering more than 90 percent of the globe every two days, NSCAT will provide more than 100 times the amount of ocean wind information currently available from ship reports, according to Graf. Since NSCAT is a radar instrument, it is capable of taking dat a day and night, regardless of sunlight or weather conditions.

The launch of a TOMS sensor aboard ADEOS will help extend the unique data set of global total column ozone measurements begun by a TOMS carried aboard NASA's Nimbus-7 satellite in 1978. "TOMS/ADEOS will continue this global mapping, while the NASA TOMS Ea rth Probe satellite, launched into a lower orbit in July, will compensate for cloud-covered regions and provide higher-resolution measurements of tropospheric aerosols and pollutants," said Phil Sabelhaus, manager of the Total Ozone Mapping Spectrometer P roject at NASA's Goddard Space Flight Center, Greenbelt, MD.

Data from both NSCAT and TOMS/ADEOS "will be very valuable to the National Weather Service," said Susan Zevin, Deputy Director for the National Weather Service, an agency of the National Oceanic and Atmospheric Administration. The ocean surface wind measu rements, used in numerical models, will help local weather forecasters more accurately predict the path and intensity of hurricanes, winter storms, and other weather systems that form over the oceans. The ozone data will be used by the National Weather Se rvice to monitor volcanic ash in the atmosphere to improve aviation safety, and to help generate a daily forecast of ultraviolet exposure levels to help reduce peoples' overexposure to the Sun's rays. Other science instruments on ADEOS provided by agencies in Japan and France will study ocean chlorophyll production and ocean temperature, land vegetation distribution, the vertical profile of atmospheric gases such as carbon dioxide, methane, and water v apor, and the polarization and direction of solar energy reflected by the Earth.