1995-5    FOR RELEASE: March 15-22, 1995

Contact:  Joan Vandiver Frisch
UCAR Media Relations
(303) 497-8607; Fax 303-497-8610
E-mail:  jfrisch@ucar.edu

Project contacts:  
Michael Exner, GPS/MET program manager, 303-497-2601, 
exner@ucar.edu
Randolph Ware, director, UNAVCO, 303-497-8005, ware@ucar.edu
Y. William Kuo, NCAR scientist, 303-497-8910, kuo@ucar.edu

Revolution in Atmospheric Monitoring Could Improve 
Weather Forecasts, Measure Global Warming

BOULDER--This spring (date to be announced), a Pegasus rocket borne 
into the sky by plane from California's Vandenberg Air Force Base will 
launch a small research satellite into low-earth orbit.  If this proof of 
concept goes well, the satellite's modest secondary payload, a shoe box-
sized radio receiver, could lead to a revolution in the collection of weather 
data worldwide and in detection of early stages of global warming caused 
by the buildup of greenhouse gases. 
 
The National Science Foundation (NSF), Federal Aviation 
Administration, National Oceanic and Atmospheric Administration, and 
National Aeronautics and Space Administration are backing the test 
project with $3.3 million over three years.  Scientific participants are the 
University NAVSTAR Consortium (UNAVCO) and the National Center 
for Atmospheric Research (NCAR), both sponsored by NSF and based in 
Boulder, Colorado; NASA's Jet Propulsion Laboratory (JPL); and the 
University of Arizona.  NASA is sponsoring the satellite's primary
payload, a lightning-mapping device. UNAVCO director Randolph Ware 
is principal investigator.

Benjamin Herman, an atmospheric scientist at the University of Arizona, 
says, "If this works, the wealth of high-resolution data that will be 
available for studying climate change and for weather forecasting will be 
tremendous.  This would be a very economical way of getting global 
weather and climate data with a time and space resolution that is 
undreamed of today with current systems." 

Called GPS/MET, the orbiting receiver will use radio signals from the U.S.
Air Force's 24 Global Positioning System (GPS) satellites to gather
meteorological data around the globe.  The small receiver will catch the 
radio beams 500 times a day as the GPS satellites rise and set at the earth's
horizon.  Starting from the top of the earth's atmosphere, the signals slow 
down and bend as they pass through lower, denser layers of air-just as 
light waves are refracted as they pass through a glass of water.  For those 
relying  on GPS signals as a navigational aid or for measuring tiny 
motions in the earth's crust, the refraction has been a distracting "noise" 
that must be removed to determine the satellites' true position.  Recently, 
however, scientists realized that this noise might be converted to highly 
accurate temperature and humidity data-a valuable signal for 
meteorologists and climatologists.  

Applications include better weather forecasts, especially over the oceans
where data are now scarce.  The Air Transport Association attributes a loss 
of at least $4 billion annually in the United States to weather-related 
aircraft delays.  Since commercial transoceanic flights are increasing at 
twice the rate of domestic flights, better short-term forecasts over the 
oceans could result in increased capacity and safety for the airline industry.  
Improved forecasts over land could save lives and property threatened by 
floods, tornadoes, drought, and other disasters.  The new data-gathering 
system could also allow scientists to track climate warming by detecting 
changes in stratospheric temperatures and global water vapor, a powerful 
greenhouse gas.  All this comes with a price tag well below the cost of 
current systems.  According to GPS program manager Michael Exner, "A 
constellation of 50 to 100 GPS microsatellites, each small enough to be 
carried by one person, could provide real-time global data for about the 
cost of one conventional weather satellite, including launch costs."

JPL and Stanford University first used radio occultation in the 1970s and
1980s on the Mariner and Voyager missions to measure atmospheric 
properties of Mars, Venus, and Neptune.  GPS/MET is the first test of the 
technique's usefulness in studying the earth's atmosphere.  

Besides Ware, Exner, and Herman, the experiment's investigators are Y.
William Kuo of NCAR, Thomas Meehan of JPL, and Christian Rocken of 
UNAVCO.  Orbital Sciences Corporation is responsible for the launch 
vehicle, satellite, and operations.  Allen Osborne Associates helped 
develop the GPS receiver for the test.  NCAR and UNAVCO are managed 
by the University Corporation for Atmospheric Research under 
sponsorship by the National Science Foundation.

-The End-


Note to the media:  Please contact Laura Ayres at Orbital Sciences 
Corporation (tel. 703-406-5528, e-mail layre@orbital.com) for press kit, 
video footage, photos, and slides.  Regarding access to live satellite link, 
contact Janet Chihocky at OSC (703-406-5525) or at Vandenberg Air Force 
Base the week of the launch (805-734-0312).

Note: The L1011 will release the Pegasus rocket at 12 kilometers (8 miles) 
altitude.

Writer:  Anatta, UCAR Communications