New Instrument May Hold the Key to Climate Studies

Glennis Nagel

As scientists around the world study the affect of atmospheric aerosols on climate, a new instrument developed on the UNK campus may hold the key.

Dr. Jon Thompson, associate professor of chemistry, and three chemistry students have developed an instrument that is able to measure both light extinction and scattering by atmospheric aerosols simultaneously on the same volume of air.

Until now, researchers have had to use two separate instruments to take the measurements independent of one another.

“This is a problem since small differences in temperature, relative humidity, or sample transfer line losses can lead to significant measurement errors,” Dr. Thompson said.

“Atmospheric aerosols are of scientific interest owing to their ability to degrade visibility, affect human health, and alter the earth’s radiative balance by scattering and absorbing incoming solar radiation,” Dr. Thompson said.

“While highly uncertain, current estimates suggest the aerosol direct and indirect effects may partially offset the warming influence of greenhouse gases,” Dr. Thompson said. “Further refinement of these estimates will be aided in part by application of this improved measurement technology for determining light extinction and scattering by atmospheric particulate matter.”

The research, which was made possible by a two-year, $152,000 grant from the National Science Foundation’s Atmospheric Sciences and Physical and Dynamic Meteorology Divisions, is being published this month in the peer-reviewed journal “Optics Express.”

“Three undergraduate chemistry students were directly involved in the design, construction and initial testing of the new instrument,” Dr. Thompson said. The three students are Nick Barta of Raymond, Danielle Policarpio of Kearney and Rick DuVall of Omaha. The three have been involved with development of the instrument over the past year. Last summer, Policarpio incorporated her work on the project into the Summer Student Research Program, while Barta and DuVall worked with support from the NSF grant.

One common source of atmospheric aerosols, Dr. Thompson noted, is the combustion of coal to generate electricity.

“The combustion of coal results in sulfur dioxide gas, which then reacts in the atmosphere to make particulates,” he said. He also noted the absorptive affects of soot created by trucks and busses.

“On average, we don’t have as much particulate matter in the air in Nebraska as they have in other parts of the country–particularly the southeast,” he said.

However, last Fourth of July, while many were thinking of picnics and barbecues, Dr. Thompson was thinking about air quality. He used the new instrument to measure particulates by sampling air through a window on the north side of Bruner Hall of Science.

The instrument was able to detect the particulate pollution produced by the various fireworks that had been shot off in the area.

The particulates dispersed in the atmosphere are believed to result in temperature changes and alteration of precipitation patterns.

Dr. Thompson noted that climate modelers want to study absorption of light by aerosol particles and how it relates to the changes in precipitation patterns.

“The instrument could be used for that purpose” he said.

Already, he and his students are working on refining the current instrument to improve its abilities to measure aerosols in air samples.

“One problem we have is that it takes 30 minutes to flush out the instrument with a new sample,” he said. “We need to improve that.”

“One thing I would like to do would be to participate in field studies using the new instrument,” he said. He’s currently planning collaborative measurements with a faculty member at Colorado State University in the coming months.

“You can come up with a ton of new ideas for field studies geographically close,” he concluded.