Rivers of Ice
Antarctica, which has a surface that is 97 percent ice, covers an area larger
than the United States and Mexico combined. Until recently, large swaths
of the continent remained unmapped. New technology has finally made it
possible to produce a complete, highly detailed map.
What does the new map reveal about the world’s iciest continent?
I
n 1995, NASA launched the
Canadian satellite RADARSAT. One
of many goals set for RADARSAT was
the collecting of images for a new
map of Antarctica. Unlike those
satellites that depend on sunlight to
illuminate the surface they are
imaging, RADARSAT provides its own
microwave illumination, and its radar
signals can penetrate the dense cloud
cover that often shrouds parts of
Antarctica. RADARSAT captured a
complete set of images of Antarctica
in just 18 days. A previous, less
accurate satellite-image map took
years to complete.
Some of the most intriguing
features shown on the map are the
ice streams that slice through the
Antarctic ice sheet. The map reveals
just how immense some of these
riverlike glaciers are—up to
800 kilometers in length and up to
50 kilometers wide. Ice streams move
along at the very speedy clip of about
900 meters per year. The ice streams
are 100 times faster than the ice
sheet they cut through. Like conveyor
belts, they transport snow and ice
from the continent’s interior to the
sea. Scientists estimate that one ice
stream moves about 80 cubic
THE RECOVERY GLACIER, one of the principal channels composing
the East Antarctic ice stream shown below, reaches more than
800 kilometers into the continent’s interior.
ANTARCTICA is shown in a radar image
obtained from the RADARSAT satellite.
kilometers of ice each year—enough
to bury the borough of Manhattan
under nearly a kilometer of ice.
Scientists are currently trying to
determine what role ice streams play
in the advance and retreat of the
West Antarctic ice sheet and why
they sometimes slow down and even
flow backward. One theory suggests
they play a regulatory role—keeping
the ice sheet from growing so large
that it would collapse under its own
weight.
Extension
RESEARCH ACTIVITY
RADARSAT’s technology has
allowed researchers to gather more
information about Antarctica than
ever before possible. What are
some other ways RADARSAT could
be used to study Antarctica? What
would you like to know about
Antarctica?
CLASSZONE.COM
Learn more about Antarctic
research.
Keycode: ES1503
Chapter 15 Glaciers
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