PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.  TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Contact:  Mary A. Hardin

FOR IMMEDIATE RELEASE                          November 18, 1996

INGENUITY ALLOWS NASA SCATTEROMETER TO STUDY ICE, RAINFORESTS

     Recent images produced from the NASA Scatterometer (NSCAT) 
are giving scientists new insights into the Antarctic ice sheet 
and the Amazon rainforest after researchers devised ways of using 
the ocean-monitoring instrument to study land and ice.

     The scatterometer's primary function is to study winds over 
the oceans, but a scientist at Brigham Young University (BYU), 
Provo, Utah, has come up with a way of enhancing the resolution 
of  the instrument's radar backscatter to take a detailed look at 
land and ice surfaces as well.

     "A radar scatterometer measures the radar backscattering 
cross-section of the Earth's surface.  Measurements of the 
backscatter over the ocean are used to infer the near-surface 
wind speed and direction, but can also be used over land to study 
ice and vegetation," said Dr. David Long, an NSCAT team member at 
BYU.  "Areas which reflect more microwaves are typically rougher 
and appear brighter in the images than smoother areas which 
reflect less.  The electrical properties of the surface also 
affect the image brightness. This is the first time we've been 
able to provide rapid, global coverage that is both uniform and 
accurate at this resolution."

     The polar regions play a central role in regulating global 
climate, and it is important to accurately record and monitor the 
extent and surface conditions of the Earth's major ice masses, 
according to Long. Scientists are using the Antarctic image to 
understand the effects of the ice pack on the ocean and climate 
systems.  The image shows variations in the ice sheet, as well as 
a "super-iceberg" that broke off the Thwaites ice tongue and is 
now circulating in the sea-ice pack.  

     "Spaceborne radar remote sensors are uniquely well-suited 
for mapping the polar regions since the radar can image the 
surface through clouds and both day and night.    Similarly, 
radars are also useful for vegetation studies because different 
vegetation types and densities have different radar responses," 
Long said. "Tropical rainforests are critical to the climatic 
health of  the Earth and are thought to contain half of all the 
world's species."
     
     The new NSCAT image shows the extent of the tropical 
rainforest.  The false color image is being used by scientists to 
identify types of vegetation on the surface which allows them to 
differentiate between areas of tropical rainforest and regions of  
woodlands and savanna.    

     "This technique of using the scatterometer to study land and 
ice is a great new application of this radar instrument. We can 
get measurements of ice extent for use in
research and as an aid to shipping and we get them accurately and 
frequently under all weather conditions," said Jim Graf, the 
NSCAT Project Manger at JPL. "We can view large-scale vegetation 
changes enabling us to track the processes of desertification and 
deforestation. Data from the NSCAT instrument is extremely 
versatile and can be used to measure short-term changes over the 
oceans and long-term changes over the land and ice."
      
     The scatterometer uses an array of stick-like antennas that 
radiate microwave pulses in the Ku-band across broad regions of 
the Earth's surface.  A small fraction of the  energy in the 
radar pulses is reflected back and captured by NSCAT's antennas.  
At any given time NSCAT's array of six dual beam antennas scans 
two swaths of ocean or land --one on either side of the 
satellite's near-polar, sun-synchronous 800-kilometer (500-mile) 
orbit.  Each swath is 600 kilometers (375 miles) wide.  The 
swaths are separated by a gap of about 350 kilometers (215 miles) 
directly below the satellite, where no data collection is 
possible.

     The scatterometer makes 50-kilometer (30-mile) resolution 
measurements of the wind over the oceans.  This resolution is too 
coarse for most land and ice studies, but through computer 
processing of the data, Long is able to produce images with a 
resolution of 8 kilometers (4.8 miles) or better. "This 
resolution is still coarse when compared with photographs, but it 
is nearly ideal for studying many land and ice processes," Long 
concluded. 

     The NSCAT instrument was launched August 16, 1996, aboard 
Japan's Advanced Earth Observing Satellite (ADEOS).  ADEOS is an 
international global change research mission of the National 
Space Development Agency of Japan (NASDA), which includes 
instruments from the United States, Japan and France and 
investigators from many other countries.  The satellite is a key 
part of an international environmental research effort that 
includes NASA's Mission to Planet Earth (MTPE) program, a long-
term, coordinated research effort to study the Earth as a global 
environmental system.  The goal of MTPE is to develop a better 
scientific understanding of natural environmental changes and to 
distinguish between natural and human-made changes and impacts.

     The Jet Propulsion Laboratory developed, built and manages 
the NSCAT instrument for NASA's Office of Mission to Planet 
Earth, Washington, D.C.

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