ARB Research Seminar

This page updated June 19, 2013

Source Apportionment of Airborne Particulate Matter Using a Mechanistic Air Quality Model

Michael J. Kleeman, Ph.D., Department of Civil and Environmental Engineering, University of California, Davis

May 21, 2001
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA


Particulate matter in a typical urban atmosphere originates from many different man-made and natural sources. Some of these sources directly emit primary particles while others release precursor gases that react to form secondary particulate matter. Faced with this complexity, decision makers need tools that clearly show the relationship between emissions sources and ambient particle concentrations. Traditional methods for source apportionment identify the contribution that sources make to airborne particle concentrations using statistical techniques to analyze the variation of airborne particle composition. Statistical source apportionment methods can be applied to a broad range of problems because they do not require detailed knowledge about meteorology or emissions inventories, but the resolution of statistical techniques is limited (8-10 sources) and these techniques cannot evaluate the response of airborne particle concentrations to emissions changes. Recently, a source-oriented mechanistic air quality model has been developed that directly tracks particle emissions from different sources through a full photochemical air quality model with aerosol processes. This new model can predict the contribution that thousands of different sources make to airborne particle concentrations in an urban atmosphere. The mechanistic source-apportionment model does not rely on tracers for source-differentiation and so the contribution from identical sources at different locations also can be quantified. The ability of the source-oriented external mixture model to identify different features of the airborne particle size and composition distribution will be illustrated through application to Southern California.

Speaker Biography

Michael J. Kleeman is an Assistant Professor of the Department of Civil and Environmental Engineering at the University of California, Davis. His main interests are the study of urban and regional air quality problems with an emphasis on the size and composition of atmospheric particles and gas-to-particle conversion processes. Professor Kleeman's research program balances experiment, theory, and modeling to approach air quality problems from multiple directions. Current projects include the development of a source-oriented external mixture model for application in central California, and an evaluation of the impact that climate change will have on urban / regional PM2.5 concentrations.

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