MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
Contact: Mary Hardin
FOR IMMEDIATE RELEASEJune 17, 1998
RADAR SYSTEM ABOARD NASA DC-8 AIMS TO UNVEIL THE MYSTERIES OF CLOUD STRUCTURES
In an effort to better understand clouds and how they affect our
environment, a NASA DC-8 aircraft is flying this week carrying an airborne
radar system designed to study the structure of clouds, including cloud
liquid water content.
During the current flights over the southern United States, NASA's
Airborne Cloud Radar is looking at clouds in an attempt to better
understand how clouds warm or cool Earth's atmosphere and how the presence
of clouds influences the world's climate.
"Clouds represent a scientific puzzle that researchers have been trying
to piece together for centuries," said Dr. Fuk Li, the principal
investigator for the cloud radar at NASA's Jet Propulsion Laboratory,
Pasadena, CA. "Scientists still don't know very much about the internal,
vertical structures of clouds, and that leads to uncertainties in weather
and climate predictions. Using the cloud radar, we will be able to study
clouds in a new way that will help us understand their structure like never
before. Once we have the cloud vertical structure information, atmospheric
scientists will have a much better handle on long-term predictions of
weather and climate change."
The cloud radar experiment was installed last month looking downward in
the tail area of the DC-8, based at NASA's Dryden Flight Research Center,
Edwards, CA. The DC-8 then flew to Tinker Air Force Base near Oklahoma
City, OK, the origination point of this series of missions in which the
radar collects cloud data while the plane flies above the clouds.
Scientists will compare these data with measurements taken by satellite
and ground-based sensors, including the Department of Energy's Southern
Great Plains Cloud and Radiation Testbed, a series of instruments spread
across north central Oklahoma and south central Kansas.
The radar, taking vertical measurements of the clouds from above,
operates at 94 gigahertz, making it sensitive to cloud particles. The
instrument transmits radar energy, which bounces off the cloud particles
and is reflected back towards the aircraft. The radar measurements will be
combined with information provided by other sensors to help analyze the
properties of the clouds observed.
This experiment has flown twice before aboard the DC-8 while still
under development. The DC-8's unique features make it an ideal platform
for examining cloud structures, according to DC-8 mission manager Chris
Jennison of Dryden.
"The DC-8 was selected because it is the only aircraft that is capable
of this mission in terms of altitude, speed, range and capacity for
carrying scientists onboard. Since scientists can fly on the aircraft,
they can operate their experiments themselves," Jennison said.
This Airborne Cloud Radar flight series is expected to total 20 flight
hours. The experiment is designed to test several hypotheses and
techniques related to satellite remote sensing of extensive, long-lasting,
non-precipitating layers of cloud in the middle and upper troposphere --
atmosphere up to about 11 kilometers (seven miles) from Earth's surface.
It is expected that this instrument will be used in upcoming field
experiments to better understand cloud-climate processes. One such planned
experiment is the Tropical Cirrus Experiment called CRYSTAL planned for
2001. Eventually this instrument will be flown on satellite platforms
designed to observe Earth's climate processes from space.
The Jet Propulsion Laboratory, a division of the California Institute
of Technology, developed the Airborne Cloud Radar in conjunction with the
University of Massachusetts, Amherst; Colorado State University, Ft.
Collins; and Pennsylvania State University, Philadelphia.
The Airborne Cloud Radar is part of NASA's Earth Science enterprise, a
long-term research program designed to study Earth's land, oceans,
atmosphere, ice and life as a total integrated system.
Note to Editors: A NASA TV video file about the airborne cloud radar
will air at 9 a.m., 12 noon, 3 p.m., 6 p.m. and 9 p.m. Pacific Daylight
Time on Wednesday, June 17. NASA TV is carried on GE-2, transponder 9C at
85 degrees west longitude, with vertical polarization, frequency 3880.0
megahertz, audio 6.8 megahertz.