PC Media 4/PC MEDIA CD04.iso/nasa/sc-alber.txt

Text File | 1995-02-23 | 4KB | 71 lines

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109.  TELEPHONE: [phone]

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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