Studies of cirrus clouds by some 150 scientists may lead to improved
forecasts of future climate change.

Beginning next summer, scientists from NASA, other government agencies,
academia and industry will investigate cirrus clouds in Florida with the
objective of reducing uncertainties in forecasts of the Earth’s future
climate. The project focuses on studies of high, tropical cirrus clouds.
These clouds are composed of tiny ice crystals that float at altitudes from
20,000 feet (6,067 meters) to 55,000 feet (16,683 meters). Scientists will
take measurements from a variety of aircraft and ground instruments for
four to six weeks beginning in July. Analysis and reporting of the data are
expected to take about two years.

“Our objective is to find out how ice clouds affect global warming,” said
Eric Jensen, project mission scientist based at NASA Ames Research Center
in the heart of California’s Silicon Valley. “The combination of
measurements and computer modeling studies will improve our understanding
of how cirrus may change in response to climate change,” he said. “For
example, as the surface heats up and thunderstorms become more intense,
will larger, thicker cirrus clouds be formed?”

“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

The effort is called the Cirrus Regional Study of Tropical Anvils and
Cirrus Layers – Florida Area Cirrus Experiment (CRYSTAL-FACE). Participants
include researchers from various NASA centers including Ames; Goddard Space
Flight Center, Greenbelt, Md.; Langley Research Center, Hampton, Va.; and
Jet Propulsion Laboratory, Pasadena, Calif. Other participating researchers
are from the National Oceanic and Atmospheric Administration, the National
Center for Atmospheric Research, Boulder, Colo.; and various universities
and companies. For a complete list of participants, please consult the
project website at

A major scientific goal is to use cloud measurements from aircraft to
calibrate cloud readings from satellites so characteristics of clouds can
be observed more accurately from the higher altitudes of orbiting
spacecraft. Better-calibrated satellite observations of clouds will result
in better large-scale measurements of clouds because satellites can see
huge areas of the globe at once. These satellite cloud readings will enable
scientists to make more accurate regional and global cirrus cloud computer
models that should reduce the uncertainty of climate change predictions,
Jensen said.

“We anticipate flights will mostly be over southern Florida, and
occasionally we will sample clouds over the ocean,” Jensen said.

Six aircraft types will carry instruments to measure cirrus clouds. The
high-flying ER-2 (similar to a U-2), based at NASA Dryden Flight Research
Center, Edwards, Calif., will conduct remote sensing of cirrus clouds and
environmental conditions. Scientists will compare the ER-2 instrument
readings with similar satellite measurements.

The Proteus aircraft from NASA Goddard’s Wallops Flight Facility, Wallops
Island, Va., also will be making remote-sensing observations of cirrus
clouds and environmental conditions.

The WB-57 aircraft based at NASA Johnson Space Center, Houston, will be
making in situ measurements of cirrus clouds and environmental conditions.
A Citation aircraft from the University of North Dakota will make in situ
measurements in the lower parts of cirrus ‘anvils.’ An anvil is an
extensive ice cloud that forms at the tops of deep thunderstorm clouds.

In addition, P-3 aircraft will use airborne radar to measure cloud
structure and intensity. A Twin Otter airplane from the Center for
Interdisciplinary Remotely Piloted Aircraft Studies, which is part of the
Naval Postgraduate School and is based at the Navy Airport near Fort Ord,
Calif., will make in situ measurements of aerosols and take other readings.
Ground-based instruments in the study include radar and other instruments.

Satellites included in the study will be GOES, Terra, Tropical Rainfall
Measuring Mission and the Aqua satellite currently scheduled for launch
next year.

In addition to Jensen, other scientists from NASA Ames will take part in
the CRYSTAL-FACE project. They include Andrew Ackerman and Katja Drdla,
Jensen’s co-investigators who are working on cirrus cloud computer
modeling. Peter Pilewskie of Ames and his colleagues will use instruments
on the ER-2 and Twin Otter aircraft to measure trapping of heat and
reflection of sunlight by clouds. Max Loewenstein’s experiment includes
measurements of carbon monoxide and methane. Paul Bui and others from Ames
are responsible for measurements from the WB-57 and ER-2 aircraft of
temperature, pressure and winds. Henry Selkirk and Leonhard Pfister are
studying development and movement of cirrus clouds. Selkirk and Pfister
also are helping with meteorological support.

Project manager Michael Craig of the Ames Earth Science Project Office is
in charge of the field campaign for NASA.