Friday, December 11, 2009
Global Team To Improve Predictions About Air Quality and ClimatePITTSBURGH—Carnegie Mellon University's Neil Donahue and Allen Robinson are working with a team of more than 60 scientists, including researchers from the University of Colorado and the NOAA's Cooperative Institute for Research in Environmental Science, to develop a more holistic approach to improving climate and air quality prediction models. Donahue and Robinson are co-authors of a study that appears in the Dec. 11 issue of the journal Science.
Donahue, head of Carnegie Mellon's Center for Atmospheric Particle Studies (CAPS), created a chemical map that provides some of the first clear images of how organic aerosols change once they become part of the atmosphere, while Robinson led an experimental team demonstrating those changes for aerosols emitted from diesel engines and wood fires.
"The atmosphere acts like Dan Aykroyd's Bass-O-Matic. It makes similar looking goop almost no matter what you start with; could be diesel soot, could be wood smoke, could be molecules emitted by trees. Once the atmosphere is done, it all looks the same," said Donahue, an atmospheric chemist.
"The blurring of the emissions of different sources is potentially a very important simplification, which is key to improving air quality and climate models," said Robinson, an engineer whose research focuses on the sources of atmospheric aerosols.
"Atmospheric processing alters the effects of aerosols on climate and human health. It appears to greatly simplify the effect of the aerosols from different sources on cloud formation and rainfall," Robinson said.
Donahue reports that his map tracks two key properties — volatility (the tendency to evaporate) and the oxygen to carbon ratio — that evolve as particles make their way through the atmosphere. "This ratio is important because it is an indicator of how much the organic matter is gaining oxygen and building up on particles floating in the air. The chemical roadmap also can help people predict the ability of the particles to participate in cloud formation," Donahue said.
For more than a decade, Carnegie Mellon researchers have been working to pinpoint the sources and effects of harmful atmospheric particles. Better known as PM2.5, these tiny, almost invisible particles can be breathed more easily into the lungs than larger dust particles and can have adverse effects on human health.
"Pittsburgh suffers from high PM levels, due to a combination of high regional background levels and local emissions, many of them organic," Robinson said. "This new map will help us understand how and when these two sources interact to create local pollutant hot spots."
"This new collaborative effort will take a lot of mystery out of how and where these airborne particles go and how they impact both humans and our climate," said Donahue, whose work focuses on chemical production and transformation of particles in the atmosphere.
The research was funded with grants from the National Science Foundation, the U.S. Department of Energy and the U.S. Environmental Protection Agency. The research team included scientists from more than 30 institutes and international collaborators from England, Switzerland, China, Japan, Mexico, Germany, Sweden and Finland.
By: Chriss Swaney