NASA Mission Will Look at Clouds From Both Sides

“I’ve looked at clouds from both sides now, from up and
down and still somehow
It’s clouds’ illusions I recall. I really don’t know clouds
at all…”

So laments Joni Mitchell’s classic song, “Both Sides Now,”
appropriate words as NASA prepares for a mission that should
remove much of the mystery from those “rows and flows of
angel hair” that so affect Earth’s weather and climate, yet
are so misunderstood.

CloudSat, the most advanced radar designed to measure the
properties of clouds, will provide the first global
measurements of cloud thickness, height, water and ice
content, and a wide range of precipitation data linked to
cloud development. The Earth System Science Pathfinder
Mission is expected to improve weather forecasting and
advance our understanding of key climate processes during
its two-year design lifetime. CloudSat is planned for launch
in 2004 aboard a Boeing Delta rocket from Vandenberg Air
Force Base, Calif. The Jet Propulsion Laboratory (JPL),
Pasadena, Calif., manages the mission for NASA’s Earth
Explorers Program Office at the Goddard Space Flight Center,
Greenbelt, Md.

“Despite the fundamental role of clouds in climate and
weather, there is much we do not know about them,” said
CloudSat Principal Investigator Dr. Graeme Stephens of
Colorado State University’s Department of Atmospheric
Science, Fort Collins, Colo. “The lack of understanding of
cloud feedback is widely acknowledged in the scientific
community to be a major obstacle confronting credible
prediction of climate change. CloudSat aims to provide
observations necessary to greatly advance understanding of
climate issues,” he said.

Stephens and Co-Principal Investigator Dr. Deborah Vane of
JPL discuss the necessity of CloudSat’s measurements in the
current Bulletin of the American Meteorological Society “The
vertical profiles of global cloud properties provided by
CloudSat will fill a critical gap in the understanding of
how clouds affect climate, uncovering new knowledge about
clouds and precipitation, and the connection of clouds to
the large-scale motions of Earth’s atmosphere,” Vane said.

CloudSat will help researchers in numerous disciplines. It
will provide better understanding of climate processes by
supporting new, detailed investigations of how clouds
determine Earth’s energy balance; how the Earth responds to
the incoming solar energy that fuels the climate system.

It will improve weather prediction models by measuring cloud
properties from the top of the atmosphere to Earth’s
surface, filling in a gap in existing and planned space
observational systems. CloudSat’s radar can penetrate thick
cloud systems, providing information to increase the
accuracy of severe storm, hurricane and flood warnings.
CloudSat will improve water resource management by linking
climate conditions such as El Nino to hydrological processes
that affect drought, severe weather and water supply
availability. The mission will also develop advanced
technologies, including high-power radar sources, methods of
radar signal transmission within spacecraft, and integrated
geophysical retrieval algorithms.

CloudSat will fly in orbital formation with NASA’s Aqua and
Aura satellites, the French Space Agency’s (CNES) PARASOL
satellite, and the NASA-CNES CALIPSO satellite. Its radar
measurements will overlap those of the other satellites. It
will be the first time five research satellites fly
together. The precision of the radar overlap creates a
unique multi-satellite observing system, providing
unsurpassed information about the role of clouds in weather
and climate.

Colorado State’s Stephens conceived CloudSat. JPL, with the
Canadian Space Agency, developed the mission’s first-ever
space borne millimeter wavelength profiling radar, which
measures the altitude and physical properties of clouds.
Ball Aerospace, Boulder, Colo., is building the spacecraft.
The U.S. Air Force will operate CloudSat on-orbit and
deliver raw data to the Cooperative Institute for Research
in the Atmosphere at Colorado State, which will process the
data for the scientific community, civilian and military
weather forecast agencies. The U.S. Department of Energy and
an international team of scientists will provide independent
verification of the radar performance through its
Atmospheric Radiation Measurement Program.

NASA’s Earth Science Enterprise is dedicated to
understanding the Earth as an integrated system and applying
Earth system science to improve prediction of climate,
weather, and natural hazards using the vantage point of
space. This mandate is part of NASA’s overall mission to
understand and protect our home planet. The California
Institute of Technology in Pasadena manages JPL for NASA.