These views of the Russian Arctic were acquired by NASA's Multi-angle
Imaging SpectroRadiometer (MISR) instrument on July 11, 2004, when the
brief arctic summer had transformed the frozen tundra and the thousands of
lakes, channels, and rivers of the Lena Delta into a fertile wetland, and
when the usual blanket of thick snow had melted from the vast plains and
taiga forests. This set of three images cover an area in the northern part
of the Eastern Siberian Sakha Republic. The Olenek River wends northeast
from the bottom of the images to the upper left, and the top portions of
the images are dominated by the delta into which the mighty Lena River
empties when it reaches the Laptev Sea. At left is a natural color image
from MISR's nadir (vertical-viewing) camera, in which the rivers appear
murky due to the presence of sediment, and photosynthetically-active
vegetation appears green. The center image is also from MISR's nadir
camera, but is a false color view in which the predominant red color is due
to the brightness of vegetation at near-infrared wavelengths. The
most photosynthetically active parts of this area are the Lena Delta, in
the lower half of the image, and throughout the great stretch of land that
curves across the Olenek River and extends northeast beyond the relatively
barren ranges of the Volyoi mountains (the pale tan-colored area to the
right of image center).
The right-hand image is a multi-angle false-color view made from the red
band data of the 60º backward, nadir, and 60º forward cameras, displayed as
red, green and blue, respectively. Water appears blue in this image because
sun glitter makes smooth, wet surfaces look brighter at the forward
camera's view angle. Much of the landscape and many low clouds appear
purple since these surfaces are both forward and backward scattering, and
clouds that are further from the surface appear in a different spot for
each view angle, creating a rainbow-like appearance. However, the vegetated
region that is darker green in the natural color nadir image, also appears
to exhibit a faint greenish hue in the multi-angle composite. A possible
explanation for this subtle green effect is that the taiga forest trees (or
dwarf-shrubs) are not too dense here. Since the the nadir camera is more
likly to observe any gaps between the trees or shrubs, and since the
vegetation is not as bright (in the red band) as the underlying soil or
surface, the brighter underlying surface results in an area that is
relatively brighter at the nadir view angle. Accurate maps of vegetation
structural units are an essential part of understanding the seasonal
exchanges of energy and water at the Earth's surface, and of preserving the
biodiversity in these regions.
The Multiangle Imaging SpectroRadiometer observes the daylit Earth
continuously and every 9 days views the entire globe between 82° north and
82° south latitude. These data products were generated from a portion of the
imagery acquired during Terra orbit 24273. The panels cover an area of
about 230 kilometers x 420 kilometers, and utilize data from blocks
30 to 34 within World Reference System-2 path 134.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra
satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
JPL is a division of the California Institute of Technology.