JET PROPULSION LABORATORY

CALIFORNIA INSTITUTE OF TECHNOLOGY

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011

PHOTO CAPTION P-43924

April 16, 1994

Mammoth land cover map

These two images were created using data from the Spaceborne

Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR).

The image on the left is a false-color composite of the Mammoth

Mountain area in California's Sierra Nevada Mountains centered at

37.6 degrees north, 119.0 degrees west. It was acquired onboard

space shuttle Endeavour on its 67th orbit on April 13, 1994. In

the image on the left, red is C-band HV-polarization, green is C-

band HH-polarization and blue is the ratio of C-band VV-

polarization to C-band HV-polarization. On the right is a

classification map of the surface features which was developed by

SIR-C/X-SAR science team members at the University of California,

Santa Barbara. The area is about 23 by 46 kilometers (14 by 29

miles). In the classification image, the colors represent the

following surfaces:

White snow

Red frozen lake, covered by snow

Brown bare ground

Blue lake (open water)

Yellow short vegetation (mainly brush)

Green sparse forest

Dark green dense forest

Maps like this one are helpful to scientists studying snow

wettness and snow water equivelent in the snow pack. Across the

globe, over major portions of the middle and high latitudes, and

at high elevations in the tropical latitudes, snow and alpine

glaciers are the largest contributors to run-off in rivers and to

ground-water recharge. Snow hydrologists are using radar in an

attempt to estimate both the quantity of water held by seasonal

snow packs and the timing of snow melt. Snow and ice also play

important roles in regional climates; understanding the processes

in seasonal snow cover is also important for studies of the

chemical balance of alpine drainage basins. SIR-C/X-SAR is a

powerful tool because it is sensitive to most snow pack

conditions and is less influenced by weather conditions than

other remote sensing instruments, such as the Landsat satellite.

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Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar

(SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The

radars illuminate Earth with microwaves allowing detailed

observations at any time, regardless of weather or sunlight

conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band

(24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency

data will be used by the international scientific community to

better understand the global environment and how it is changing.

The SIR-C/X-SAR data, complemented by aircraft and ground

studies, will give scientists clearer insights into those

environmental changes which are caused by nature and those

changes which are induced by human activity. SIR-C was developed

by NASA's Jet Propulsion Laboratory. X-SAR was developed by the

Dornier and Alenia Spazio companies for the German space agency,

Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the

Italian space agency, Agenzia Spaziale Italiana (ASI), with the

Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v. (DLR),

the major partner in science, operations and data processing of

X-SAR.

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