Both single and multi-angle views of the breakup of the
northern section of the Larsen B ice shelf are shown in this
image pair from the Multi-angle Imaging SpectroRadiometer.
The Larsen B ice shelf collapsed and broke away from the
Antarctic Peninsula during February and March, 2002 -- a
progression observed by Terra's Moderate-resolution Imaging
SpectroRadiometer (MODIS) and analyzed at the University
of Colorado's National Snow and Ice Data Center. The collapse
is thought to have been accelerated by warm summer temperatures
which caused meltwater to fill crevasses along the landward side
of the Larsen shelf, leading to intensified pressures within the
sheet structure.
In the left-hand view, spectral variations across the scene are
highlighted by using near-infrared, red and blue data from
MISR's nadir (vertical-viewing) camera. Here, the ice within the
disintegrating ice shelf appears vibrant blue. Water has an
intrinsic blue color due to the selective absorption of longer
wavelengths such as red and infrared, and the translucent properties
of ice within the collapsing shelf enables this absorption to be
observed. The use of the near-infrared band within this false-color
composite accentuates the effect. Light brownish streaks across
the splintering sheet can also be discerned, and probably indicate
regions where rocks and morainal debris were exposed from the
interior of the shelf.
On the right, data from three different view angles and
only one color channel were combined to create a multi-angle
composite. This image displays red-band data from MISR's 46-degree
forward, nadir, and 46-degree backward-viewing cameras as red,
green and blue, respectively. Here, the disintegrating ice shelf
and the rough crevasses of glaciers appear orange. In contrast
to the spectral composite, which provides information on the
chemical composition of water ice, the colors in the right-hand
image represent properties related to its physical nature.
Because vertical protrusions or depressions within textured surfaces
appear brighter on their illuminated faces, the orange color in the
multi-angle composite suggests a macroscopically rough ice surface.
Low clouds in the multi-angle view appear purple due to their
ability to both forward scatter and backward scatter sunlight. Higher
clouds and mountainous terrain are subject to geometric parallax which
splits the imagery into spatially separated components, and their
unusual appearance is an artifact of this effect.
These views were acquired on March 7, 2002, during Terra orbit 11798.
Each image represents an area of approximately 149 kilometers x
186 kilometers.
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.
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