Round-the-world mission puts greenhouse gases in laser focus

zondlo-laser.jpgA new version of the laser system will test for ammonia, a major pollutant produced by farming. 

zondlo-on-plane.jpgMark Zondlo chased an airplane last fall from Alaska to New Zealand. Zondlo, an assistant professor of civil and environmental engineering, took commercial flights to follow a National Science Foundation aircraft that collected data on how humans are changing climate. Laserbased sensors mounted on the aircraft measured water vapor to see if pollutants change the degree of cloudiness.

zondlo-airplaine_cropped.jpgMark Zondlo, an assistant professor of civil and environmental engineering, studied the effects of pollution on rainfall by sending a laser-based sensor from the North to the South Pole atop an airplane (in Alaska, above).

"The largest uncertainties in climate involve human-generated aerosols in clouds," said Zondlo, over the phone from an Alaskan airport. "They could make it warmer or colder. We're not sure."

Zondlo developed the sensors with colleagues at Mid-infrared Technologies for Health and the Environment (MIRTHE), a Princeton-based center focused on using lasers to measure minute quantities of gases. He's working on a new sensor with Princeton graduate student David Miller to measure ammonia, a gas produced primarily by farming. By repeatedly bouncing a beam through air between two mirrors, the sensor allows for ultra-sensitive measurements.

"Almost all aerosol particles contain ammonia," Zondlo said, before flying to New Zealand, where he boarded the research aircraft bound for Antarctica. "But it's really hard to measure because you're looking for one molecule of ammonia among a trillion molecules of air. We can do that with these multiple-pass sensors."