On Jan. 28, 2017, a DC-8 plane with 25,000 pounds of scientific instruments will take off from California.  In 26 days, it will crisscross the northern and southern hemispheres, touching down in Alaska, Hawaii, Fiji, New Zealand, Chile, Ascension Island, Azores Islands, and Greenland before returning to California. Along the way, scientists on board will sample the atmosphere and analyze for hundreds of chemical species.

When this mission is complete, the world will have for the first time a map of the global distribution of chemical species in the atmosphere as a function of latitude and altitude. The data will help answer unsettled questions about climate change and improve the predictive ability of mathematical models of atmospheric processes.     

School of Earth and Atmospheric Sciences (EAS) Professor and Chair Greg Huey joins the mission in Christchurch, New Zealand, on Feb. 6. He will replace his colleague David Tanner in tending the Georgia Tech scientific payload—a chemical ionization mass spectrometer, which is continuously monitoring levels of peroxyacetyl nitrate (PAN). The compound—a product of the reaction between volatile organic compounds and nitrogen oxides (NOx)—is a good tracer for biomass burning. Monitoring it, Huey says, “lets you trace the chemistry of the atmosphere as you fly along.”

The Georgia Tech team will also collect samples for analysis of brown carbon aerosols, which consist of various organic compounds that absorb light. Brown carbon aerosols may be important because they influence the radiation balance of the planet, just as greenhouse gases do. But little is known about these atmospheric components because few measurements have been made.    

To trap the aerosols, the air inlets to the DC-8 flying laboratory are fitted with filters, which are changed every 15 minutes. When the samples arrive at Georgia Tech, they will be analyzed in the lab of EAS Professor Rodney Weber.

The Georgia Tech team is only one of about a dozen scientific teams on NASA’s Atomic Tomography Mission (ATom) to “study the impact of human-produced air pollution on greenhouse gases and on chemically reactive gases.” Ultimately, ATom’s goal is to find effective ways to slow global warming and improve air quality.

“We’ve never done a trip like this—flying from pole to pole while going through the Atlantic and Pacific basins,” Huey says.  “When put together, the data will give a complete latitudinal picture for the distribution of numerous atmospheric species that can be used to critically test our understanding of emissions, transport, and atmospheric chemistry.

Without global data of this kind, “you don’t understand fully all the sources and sinks of greenhouse gases and aerosols,” Huey says. “If you really want to understand issues such as climate and air quality it is imperative to understand what controls greenhouse gases and oxidants globally.”

Data from ATom will be available to other researchers. For example, atmospheric modelers can use the information to challenge their models. “The only way to have predictive value is by running models,” Huey says. “And you need good data to figure out the chemistry, the emissions, and how those things change with time.” Predictions are nice. But maybe more important, Huey says, “is asking the model what to do if, for example, aerosol is predicted to be high in Atlanta this summer.”

Huey can’t wait to board NASA’s DC-8 flying laboratory. “I’m excited,” he says. “Just getting the data is a unique opportunity. Data like these are very hard to get. You don’t know if this opportunity will ever come again.”