This illustration features images of southern California and
southwestern Nevada acquired on January 3, 2001 (Terra orbit 5569),
and includes data from three of MISR's nine cameras. The San Joaquin
Valley, which comprises the southern extent of California's Central
Valley, covers much of the viewed area. Also visible are several of
the Channel Islands near the bottom, and Mono and Walker Lakes, which
stand out as darker patches near the top center, especially in the
vertical and backward oblique images. Near the lower right of each
image is the Los Angeles Basin, with the distinctive chevron shape of
the Mojave Desert to its north.
The Central Valley is a well-irrigated and richly productive
agricultural area situated between the Coast Range and the snow-capped
Sierra Nevadas. During the winter, the region is noted for its hazy
overcasts and a low, thick ground fog known as the Tule. Owing to the
effects of the atmosphere on reflected sunlight, dramatic differences
in the MISR images are apparent as the angle of view changes. An area
of thick, white fog in the San Joaquin Valley is visible in all three
of the images. However, the pervasive haze that fills most of the
valley is only slightly visible in the vertical view. At the oblique
angles, the haze is highly distinguishable against the land surface
background, particularly in the forward-viewing direction. Just above
image center, the forward view also reveals bluish-tinged plumes near
Lava Butte in Sequoia National Forest, where the National Interagency
Coordination Center reported an active forest fire.
The changing surface visibility in the multi-angle data allows us to
derive the amount of atmospheric haze. In the lower right quadrant is a
map of haze amount determined from automated processing of the MISR
imagery. Low amounts of haze are shown in blue, and a variation in hue
through shades of green, yellow, and red indicates progressively larger
amounts of airborne particulates. Due to the topographically complex
terrain, no results are obtained over the Sierra Nevada and Coastal
mountains and these areas are shown in black. However, the enhanced
haziness of the San Joaquin Valley is evident in this derived product.
Within the yellow pixels, the Sun would look about 40% dimmer to an
observer on the ground in comparison to its brightness on a much
clearer day.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
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