April 28, 2006

NASA Launches Climate Satellites

By Irene Klotz

CAPE CANAVERAL, Florida -- NASA on Friday launched two research satellites to help scientists refine computer models that forecast the weather and chart global climate change.

CloudSat and CALIPSO blasted off aboard an unmanned Delta rocket from Vandenberg Air Force Base in California at 6:02 a.m. EDT (1002 GMT) after a week of delays for weather and technical issues. The Boeing-built booster originally had been slated to fly last year, but a machinists' strike forced several months of delays.

CloudSat has powerful radar instruments to peer deep into the structure of clouds and map their water content. Although only about 1 percent of Earth's water is held in clouds, it plays a crucial role in the planet's weather, scientists working on the mission said.

"CloudSat will answer basic questions about how rain and snow are produced by clouds, how rain and snow are distributed worldwide, and how clouds affect the Earth's climate," principal investigator Graeme Stephens of Colorado State University said.

Using instruments 1,000 times more powerful than common meteorology radar CloudSat was designed to render three-dimensional maps of clouds that will identify the location and form of water molecules.

Complementary and virtually simultaneous studies by sister probe CALIPSO will pinpoint aerosol particles and track how they interact with clouds and move through the atmosphere. CALIPSO is an acronym for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations.

Aerosols are formed by natural phenomena like forest fires and human activity such as driving cars. Aerosols are considered a key factor in understanding why the planet is growing warmer and if anything can be done to stem or reverse the change.

Computer models predict average surface temperatures on Earth will increase between 3.5 degrees Celsius and 9 degrees F over the next 100 years.

The uncertainty stems from the role clouds play in moderating heat. Aerosols in the clouds can either cool the planet by reflecting solar energy back into space, or increase temperatures by trapping heat in the atmosphere.

"We need to understand the aerosol effect on climate because it counteracts the effects of greenhouse gases," said CALIPSO principal investigator David Winker of NASA's Langley Research Center in Hampton, Virginia.