An artist’s rendering of NASA's Orbiting Carbon Observatory (OCO)-2, which studies the global movement of carbon dioxide. (JPL / NASA)

NASA has its head in the clouds this year. Literally.

The space agency is kicking off five global projects designed to study how the earth’s atmosphere influences climate change.

One of those projects is a study of greenhouse gases over the eastern part of the United States, with a little help from Washington-area contractors.

Scientists think they understand what causes the emission of greenhouse gases such as carbon dioxide and methane, but they know little about the movement of these gases in the earth’s atmosphere, said Amin Nehrir, a research and instrument scientist at NASA’s Langley Research Center in Hampton, Va. The basic aim of the project, a collaboration between Langley and a team led by Kenneth Davis, a Penn State University professor, is to track their flow.

NASA awarded McLean-based Exelis a $3.5 million contract last week to modify a laser instrument so it can collect carbon dioxide measurements, making it the latest local contractor to contribute to the space agency’s carbon studies efforts.

Dulles-based Orbital Sciences launched NASA’s Orbiting Carbon Observatory into space last summer and runs its daily operations. The satellite studies the global movement of carbon dioxide from its higher perch in space. Part of the Langley team’s work is to evaluate the sensitivity of the observatory’s instruments as it performs its mission, Nehrir said.

Science Systems and Applications, a Lanham-based small business, received a contract worth up to $210 million last fall to support the development of instruments that can measure carbon levels on land and in the air.

For aerospace and defense contractor Exelis, which spun off its services unit into a new company named Vectrus last year, the NASA project is part of a strategic shift into more climate and environmental work, said Eric Webster, vice president of the company’s weather systems business.

Climate projects made up less than 1 percent of sales for the company’s geospatial division in 2013. Now, they makes up more than 15 percent of sales, according to Exelis.

The NASA contract is also a testing ground for Exelis’ laser instrument, said Webster. Eventually, scientists hope to use it in space for global readings, he said.

“Before the laser technology goes into space, it has to prove itself on ground and air applications,” he said.

What makes the atmospheric carbon project different, said Nehrir, is that it is one of the first large-scale field experiments aimed solely at understanding the behavior of greenhouse gases,without a chemistry or astronomy component.

A group of scientists plan to board two planes and conduct multiple field flights over Virginia’s Wallops Island; Shreveport, La.; and Sioux City, Iowa.

Those locations were chosen because they contain major sources of carbon dioxide, including cities and power plants, as well as “sinks,” which are natural systems that absorb carbon dioxide, such as the Appalachian mountains, Nehrir said.

Scientists plan to conduct the research over different seasons, and through fair and adverse weather conditions.

When the experiment is over, NASA’s goal is to improve existing greenhouse gas emission models and eventually, inform climate-change policy making, he said.