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U Meteorologist in CloudSat Mission

April 18, 2006 — University of Utah meteorologist Gerald “Jay” Mace plans to be at Vandenberg Air Force Base, Calif., at 4:02 a.m. MDT this Friday April 21 when a pair of NASA satellites are launched to study Earth’s clouds and aerosol haze and learn more about how they affect global warming.

Mace is a member of the science team for one of the satellites, named CloudSat. It is scheduled for launch on a Boeing Delta II rocket along with CALIPSO, which stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations.

As is the case with all space launches, delays are possible, and Mace plans to stay at Vandenberg until a launch occurs.

According to the National Aeronautics and Space Administration: “CALIPSO and CloudSat will provide new perspectives on Earth’s clouds and aerosols, answering questions about how they form, evolve and affect water supply, climate, weather and air quality. They will be launched into an orbit where they will fly just 15 seconds apart as members of NASA’s ‘A-Train,’ a constellation of several Earth-observing satellites.”

NASA says the CALIPSO satellite will separate from the rocket 62 minutes after liftoff, while CloudSat will separate 96 minutes after launch.

Mace says CloudSat contains a single instrument, “a special radar that provides for the first time the vertical structure of clouds. Unlike typical weather satellites that see only the tops of clouds by sensing either scattered sunlight or infrared radiation (which people sense as heat), CloudSat will send down a beam of energy (like that used in your microwave oven) and measure how much of that energy is reflected back to the antenna.”

“In this way, we will be able to determine how clouds are put together – like how much condensed water is in clouds and how big the particles are. This information will allow us to understand how clouds interact with the climate system.”

Clouds both trap heat near Earth’s surface and reflect heat from sunlight, but the net effect is that “clouds are known to slightly cool the climate system,” Mace says. “Slight changes in this delicate balance could either offset or enhance global warming. CloudSat and CALIPSO will allow us to monitor these effects and help improve the ability of climate models to predict climate change.”

CALIPSO will carry a laser radar, known as a lidar. “CALIPSO has essentially the same goals as CloudSat, but it will use a green laser beam to sense the clouds, unlike CloudSat’s microwave beam,” says Mace.

CloudSat, CALIPSO and the rest of the “A-Train” satellites will orbit Earth’s poles and repeat the same orbit every 16 days. Mace says the coordinated measurements “will revolutionize our understanding of clouds in the Earth climate system.”

“My involvement with this project goes back to the original attempts at acquiring funding about 10 years ago,” says Mace, who developed the computer software that will be used to analyze raw data from CloudSat, identify clouds in that data and produce the basic cloud measurements from CloudSat data. The software also will merge CloudSat data with data from the other satellites.

Mace says he and other scientists expect to get the first glimpse of data from CloudSat and CALIPSO four to six weeks after they are launched, once they have caught up with other satellites in the “A-Train.”

For more about CloudSat, see:

For more about CALIPSO, see:

Other satellites flying in close formation with CloudSat and CALIPSO include Aura, Parasol and OCO. For more information on the “A-Train” of satellites, see: