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NSF PR 01-68 - August 16, 2001
Media contact:
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Cheryl Dybas, NSF
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(703) 292-8070
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cdybas@nsf.gov
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Anatta, UCAR
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(303) 497-8604
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anatta@ucar.edu
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Program contact:
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Cliff Jacobs, NSF
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(703) 292-8521
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cjacobs@nsf.gov
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This material is available primarily
for archival purposes. Telephone numbers
or other contact information may be out
of date; please see current contact information
at media
contacts.
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Scientists Delve into the Icy Hearts of Hurricanes
(Images available at: ftp://ftp.ucar.edu/communications)
Despite its tropical origin, the upper two-thirds of
a typical hurricane is made up largely of ice. This
month scientists from the National Center for Atmospheric
Research (NCAR) in Boulder, Colorado, are bringing
unique cloudprofiling instruments into this mysterious
upper realm in a project to help improve hurricane
forecasting and modeling. Supporting NCAR’s participation
are the National Science Foundation (NSF) and NASA.
CAMEX-4, the fourth Convection And Moisture Experiment
(CAMEX), is the first of its kind for the U.S. Weather
Research Program (USWRP), a multi-agency effort to
reduce the destructive impact nationwide of disastrous
weather, particularly hurricanes.
Scientists aboard NASA's DC-8 and ER-2 research aircraft
homebased at Jacksonville (Fla.) Naval Air Station
will join satellites and other sensors to analyze
the structure and impact of hurricanes at sea and
as they hit land. The project runs from August 16
to 24 September.
"CAMEX addresses one of the most challenging forecast
problems, hurricane landfall," says Cliff Jacobs,
program director in NSF's division of atmospheric
sciences, which is funding the research. "This experiment
is particularly important because of the collaboration
on a high priority research area of the interagency
USWRP."
NCAR's Andrew Heymsfield, one of the principal investigators,
will fly seven instruments aboard the DC-8 to get
the clearest-ever picture of frozen and condensed
water within a hurricane. "A hurricane might extend
60,000 feet high, but only the bottom 15,000 feet
is in the rain phase. The upper 45,000 feet or so
is usually ice particles," explains Heymsfield, "and
that’s what we’re going to be looking at."
The huge swirls of white cloud evident on hurricane
satellite photos consist mainly of ice crystals. As
water vapor freezes to form ice, it releases vast
amounts of latent heat, which "helps to drive hurricanes,"
Heymsfield says. "You need to get the ice phase going
to really intensify the hurricane." Typical hurricane-hunting
flights operate below 20,000 feet, so they obtain
only limited information on ice content.
Heymsfield's instruments will fly as high as 43,000
feet aboard the DC-8. A sophisticated cloud particle
imager shines a tiny laser beam on an array of photo
diodes. Ice crystals passing in front of the laser
leave a shadow on the array. The resulting photos,
taken 40 times each second, show the crystal structure
in fine detail. Heymsfield has taken the imager into
cirrus clouds, but this will be its first foray into
a hurricane. With the help of other sensors that measure
overall moisture, Heymsfield and colleagues will study
how much water a hurricane deposits in its upper levels
and how much dry air it pulls down into the calm,
clear eye.
"For better forecasts of hurricane landfall and intensification,
we need to know how much ice is transported into the
upper two-thirds of a hurricane," says Heymsfield.
NSF is an independent federal agency which supports
fundamental research and education across all fields
of science and engineering, with an annual budget
of about $4.5 billion. NSF funds reach all 50 states,
through grants to about 1,800 universities and institutions
nationwide. Each year, NSF receives about 30,000 competitive
requests for funding, and makes about 10,000 new funding
awards.
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