JET PROPULSION LABORATORY

CALIFORNIA INSTITUTE OF TECHNOLOGY

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

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

PHOTO CAPTION P-43886

April 11, 1994

This is a false-color composite of Prince Albert, Canada,

centered at 53.91 north latitude and 104.69 west longitude. This

image was acquired by the Spaceborne Imaging Radar C/X-Band

Synthetic Aperture Radar (SIR-C/X-SAR) aboard space shuttle

Endeavour on its 20th orbit. The area is located 40 kilometers

(25 miles) north and 30 kilometers (20 miles) east of the town of

Prince Albert in the Saskatchewan province of Canada. The image

covers the area east of the Candle lake, between gravel surface

highways 120 and 106 and west of 106. The area in the middle of

the image covers the entire Nipawin (Narrow Hills) provincial

park. The look angle of the radar is 30 degrees and the size of

the image is approximately 20 kilometers by 50 kilometers (12 by

30 miles). The image was produced by using only the L-band. The

three polarization channels HH, HV and VV are illustrated by red,

green and blue respectively. The changes in the intensity of

each color are related to various surface conditions such as

variations in forest stands, frozen or thawed condition of the

surface, disturbances (fire and deforestation), and areas of

regrowth. Most of the dark areas in the image are the ice-

covered lakes in the region. The dark area on the top right

corner of the image is the white Gull Lake north of the

intersection of highway 120 and 913. The right middle part of

the image shows Lake Ispuchaw and Lower Fishing Lake. The

deforested areas are also shown by dark areas in the image.

Since most of the logging practice at the Prince Albert area is

around the major highways, the deforested areas can be easily

detected as small geometrically shaped dark regions along the

roads.

At the time of the SIR-C/X-SAR overpass a major part of the

forest is either frozen or undergoing the spring thaw. The L-

band HH shows a high return in the jack pine forest. The reddish

areas in the image are old jack pine forest, 12 to 17 meters (40

to 55 feet) in height and 60 to 75 years old. The orange-

greenish areas are young jack pine trees, 3 to 5 meters (10 to 16

feet) in height and 11 to 16 years old. The green areas are due

to the relative high intensity of the HV channel which is

strongly correlated with the amount of biomass. L-band HV

channel shows the biomass variations over the entire region.

Most of the green areas, when compared to the forest cover maps

are identified as black spruce trees. The dark blue and dark

purple colors show recently harvested or regrowth areas

respectively.

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).

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