These views from the Multi-angle Imaging SpectroRadiometer (MISR) illustrate
ice surface textures and cloud-top heights over the Amery Ice Shelf / Lambert
Glacier system in East Antarctica on October 25, 2002.
The left-hand panel is a natural-color view from MISR's downward-looking
(nadir) camera. The center panel is a multi-angular composite from three
MISR cameras, in which color acts as a proxy for angular reflectance
variations related to texture. Here, data from the red-band of MISR's
60º forward-viewing, nadir and 60º backward-viewing cameras are displayed
as red, green and blue, respectively. With this display technique, surfaces
which predominantly exhibit backward-scattering (generally rough surfaces)
appear red/orange, while surfaces which predominantly exhibit
forward-scattering (generally smooth surfaces) appear blue. Textural
variation for both the grounded and sea ice are apparent. The red/orange
pixels in the lower portion of the image correspond with a rough and
crevassed region near the grounding zone, that is, the area where the Lambert
and four other smaller glaciers merge and the ice starts to float as it forms
the Amery Ice Shelf. In the natural-color view, this rough ice is spectrally
blue in color.
Clouds exhibit both forward and backward-scattering properties in the middle
panel and thus appear purple, in distinct contrast with the underlying ice
and snow. An additional multi-angular technique for differentiating clouds
from ice is shown in the right-hand panel, which is a stereoscopically
derived height field retrieved using automated pattern recognition involving
data from multiple MISR cameras. Areas exhibiting insufficient spatial
contrast for stereoscopic retrieval are shown in dark gray. Clouds are
apparent as a result of their heights above the surface terrain. Polar clouds
are an important factor in weather and climate. Inadequate characterization
of cloud properties is currently responsible for large uncertainties in
climate prediction models. Identification of polar clouds, mapping of their
distributions, and retrieval of their heights provide information that will
help to reduce this uncertainty.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth
continuously and every 9 days views the entire Earth between 82 degrees north
and 82 degrees south latitude. These data products were generated from a
portion of the imagery acquired during Terra orbit 15171. The panels cover an
area of 380 kilometers x 984 kilometers, and utilize data from blocks
145 to 151 within World Reference System-2 path 127.
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.
Text acknowledgment: Clare Averill (Acro Service Corporation/Jet Propulsion
Laboratory), Helen A. Fricker (Scripps Institution of Oceanography).
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