Russia's Volga River is the largest river system in Europe, draining
over 1.3 million square kilometers of catchment area into the
Caspian Sea. The brackish Caspian is Earth's largest landlocked
water body, and its isolation from the world's oceans has enabled the
preservation of several unique animal and plant species. The Volga
provides most of the Caspian's fresh water and nutrients, and also
discharges large amounts of sediment and industrial waste
into the relatively shallow northern part of the sea. These images
of the region were captured by the Multi-angle Imaging
SpectroRadiometer on October 5, 2001, during Terra orbit 9567.
Each image represents an area of approximately 275 kilometers x
376 kilometers.
The left-hand image is from MISR's nadir (vertical-viewing) camera,
and shows how light is reflected at red, green, and blue wavelengths.
The right-hand image is a false color composite of red-band imagery
from MISR's 60-degree backward, nadir, and 60-degree forward-viewing
cameras, displayed as red, green, and blue, respectively. Here,
color variations indicate how light is reflected at different angles
of view. Water appears blue in the right-hand image, for example,
because sun glitter makes smooth, wet surfaces look brighter at the
forward camera's view angle. The rougher-textured vegetated wetlands
near the coast exhibit preferential backscattering, and consequently
appear reddish. A small cloud near the center of the delta separates
into red, green, and blue components due to geometric parallax
associated with its elevation above the surface.
Other notable features within the images include several linear
features located near the Volga Delta shoreline. These long,
thin lines are artificially maintained shipping channels, dredged
to depths of at least 2 meters. The crescent-shaped Kulaly Island,
also known as Seal Island, is visible near the right-hand edge of
the images.
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.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
|
