Chris Rink
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RELEASE : 09-082
09-082: In Chilean Desert, NASA Makes New Observations of Atmosphere
HAMPTON, Va. -- A group of NASA scientists and engineers are in the midst of an unusual field campaign in one of the world's driest places to learn more about how water vapor controls the climate of the planet.

The team from NASA's Langley Research Center in Hampton, Va., are in the Atacama Desert in Chile, using a new instrument to observe a band of infrared radiation activity of the atmosphere that is thought to account for half of all Earth's cooling emissions to space but has not been thoroughly explored. These measurements will allow a better understanding of water vapor's influence on climate and temperature the atmosphere and better predictions of Earth's climate.

The instrument, Far-Infrared Spectroscopy of the Troposphere (FIRST), measures what is called the "far infrared" portion of the electromagnetic spectrum. This part of the spectrum reveals to scientists how water vapor is absorbing or emitting radiation through Earth's greenhouse effect. Measurements made in the far infrared are key to refining science's basic understanding of the greenhouse effect and the feedbacks associated with man-made impacts on the climate. Studying the far infrared will also illuminate the role of high-altitude, heat-trapping cirrus clouds in climate.

"We are interested in water vapor at and above 17,000 feet (5,182 m) (above sea level) because the far-infrared emission from water vapor at that altitude is an important control on the energy balance of the atmosphere," said Marty Mlynczak, the principal investigator for FIRST and a senior research scientist at Langley.

Most infrared sensors currently operating cannot measure water vapor emissions in the far infrared, neither from space nor from the ground. The Langley-designed FIRST instrument is one of only four sensors worldwide that can capture water vapor emissions in the far infrared -- defined by the FIRST team as wavelengths between 15 and 100 micrometers.

The site in the Atacama Desert -- at 17,500 feet (5,334 m), about equal to the Mt. Everest base camp -- was chosen because the air is so dry, the far-infrared emission from moisture in the air can be directly observed with FIRST.

Scientists believe that far-infrared water vapor emissions to space account for about half of the Earth's natural cooling mechanism. But because technological obstacles have prevented it, this has never been thoroughly measured from satellites in space, the way most major climate factors are. In large-scale climate prediction models, theoretical calculations of this effect take the place of direct observations. Measurements are needed to validate the theory.

The campaign is also presenting an interesting test for the researchers conducting the research. The customized shipping container outfitted to house the instrument on a mountaintop includes supplemental oxygen. Spending long days at higher than 17,000 feet (5,182 m) required the additional oxygen to prevent altitude sickness and to keep minds sharp.

Rotating teams from Langley's Science and Systems Engineering directorates and Utah State University -- whose Space Dynamics Laboratory built the FIRST instrument to Langley's specs -- are spending weeks at a time in Chile. The first team arrived in late July and began measurements in mid-August. The campaign will last until late October. Lodging is at a base camp at about 8,000 feet (2,438 m), requiring a daily round trip of about three hours on mountain roads to get to and back from the research site. FIRST has been operating well and taking measurements that compare favorably with other prototype far-infrared instruments.

Building on the success of this campaign, Langley hopes to include a similar instrument on the Climate Absolute Refractivity and Reflectivity Observatory (CLARREO) mission. CLARREO, set to launch in 2016, will be the first space-borne mission to measure the Earth's radiation budget in the full infrared spectrum. These measurements will give policymakers and lawmakers data about the climate with unprecedented accuracy. FIRST is an important step toward that goal.

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