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July 16, 2002
LOOKING AT CLOUDS FROM ALL SIDES NOW
NASA-led research of cirrus clouds by more than 450
scientists could lead to improved forecasts of future climate
change -- forecasts of your weather today, tomorrow and years
into the future.
This month, NASA is conducting a field campaign in southern
Florida to investigate high tropical cirrus clouds composed
of tiny ice crystals. Researchers hope to determine how these
clouds form, how they limit the amount of sunlight reaching
the surface of the Earth and how they trap heat rising from
the surface and lower atmosphere. This key information will
provide data that will markedly improve our understanding of
these cloud systems, and thereby improve the computer models
used to forecast global climate change and its regional
impacts.
High, tropical cirrus clouds are made up of tiny ice crystals
that float at altitudes from 20,000 feet to 60,000 feet.
The campaign includes deployment of six aircraft over two
surface sites ranging in altitude from near surface to 70,000
feet. A modeling team is supporting flight planning,
preliminary data analysis to help validate the instruments'
integrity, and subsequent modeling and analysis with the goal
of developing a more complete understanding of these cloud
systems.
The aircraft will sample air flowing into and being processed
by the cloud systems and will evaluate the composition and
structure of the resulting cirrus clouds. One of the six
aircraft, the NASA ER-2, will serve as a remote sensing
platform to support satellite measurements and to extract
details of the cloud structures.
Recent observations from NASA's Terra satellite, with
improved sensitivity to detect cirrus cloud systems, suggest
that cirrus are present more than expected both temporally
and spatially across the planet. Cirrus may act to warm or
cool the planet and the tendency toward warming or cooling
depends on the extent, duration, thickness and location of
the clouds.
Satellite observations can assess the extent of cirrus. Field
campaigns, when coupled with concurrent satellite
observations, allow development of a detailed understanding
of the evolution of these cloud systems and verification of
satellite-deduced cirrus characteristics.
"Our objective is to find out how ice clouds affect global
warming and climate change," said Eric Jensen, project
mission scientist at NASA Ames Research Center, Moffett
Field, Calif. "The combination of measurements and computer-
modeling studies will improve our understanding of how cirrus
clouds may change in response to other aspects of climate
change," he explained. "For example, if the Earth's surface
heats up and thunderstorms become more intense, will larger,
thicker cirrus clouds be formed? How might these regional
climate events affect the bigger picture?"
"Clouds are the largest source of uncertainty in computerized
global climate models," Jensen said. "We want to measure the
ice crystal sizes, cloud optical depths and the heating or
cooling of the Earth's surface caused by tropical cirrus
clouds, particularly those generated by intense storms."
Optical depth is a measure of the visual or optical thickness
of a cloud.
The effort is called the Cirrus Regional Study of Tropical
Anvils and Cirrus Layers - Florida Area Cirrus Experiment
(CRYSTAL-FACE). Partner government organizations include the
National Oceanic and Atmospheric Administration, National
Science Foundation, the Department of Defense Office of Naval
Research and the Air Force, and the Department of Energy. The
Naval Air Facility, Key West, Fla., is hosting the aircraft
for this research effort.
This research is part of NASA's Earth Science Enterprise, a
long-term research effort that utilizes the unique vantage
point of space to view our home planet to better understand
and protect life here, while exploring for life in the
universe. CRYSTAL-FACE will support data validation of NASA
satellite investigations, including EOS Terra and Aqua
satellite missions and the Tropical Rainfall Measurement
Mission.
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Contacts:
David E. Steitz
Headquarters, Washington
(Phone: 202/358-1730)
John Bluck
Ames Research Center, Moffett Field, Calif.
(Phone: 650/604-5026)
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Wispy High, Thin Cirrus Clouds
During July in southern Florida, scientists from
NASA's Goddard Space Flight Center,
Greenbelt, Md. will join others to investigate
high tropical cirrus clouds like those shown in
this picture from the Space Shuttle Endeavor.
Cirrus clouds, sometimes called "mare's tails"
are composed of tiny ice crystals. The
researchers hope to determine how the clouds
form, how they limit the amount of sunlight
reaching the surface of the Earth and how
they trap heat rising from the surface and
lower atmosphere. This key information will
help improve computer programs that forecast
global climate change.
Credit: Space Shuttle Endeavour on July 1,
1993 (STS-57)
Cirrus Clouds and a Sun Dog
A bright "Sun Dog" lingers amidst these wispy
cirrus clouds floating over Sanibel Island,
Florida. A Sun Dog a bright spot to the left or
right of the Sun, created when sunlight is
refracted off of the ice crystals in the cirrus
clouds. Courtesy: Mike Phelps, Storm
Photographer
NASA WB-57 Flies for CRYSTAL-FACE Mission
The NASA Johnson Space Center (JSC) in
Houston, Texas is the home of the NASA
WB-57 High Altitude Research Program. Two
fully operational WB-57 aircraft are based near
JSC at Ellington Field. Both aircraft have been
flying research missions since the early
1960's, and continue to be an asset to the
scientific community with professional, reliable,
customer-oriented service designed to meet all
scientific objectives. Credit: NASA
NASA's ER-2 Flying in the CRYSTAL-FACE Mission
The ER-2 is a civilian version of the Air Force's
U2-S reconnaissance platform. These
high-altitude aircraft are used as platforms for
investigations that cannot be accomplished by
sensor platforms of the private sector. Aircraft
and spacecraft have proven to be excellent
platforms for remote and in situ sensing. The
ER-2, flying at the edge of space, can scan
shorelines, measure water levels, help fight
forest fires, profile the atmosphere, assess
flood damage, and sample the stratosphere.
Credit: NASA
Related Links
Crystal Face Project website
Educational and classroom materials
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