Secondary Organic Aerosol Formation:
Chamber Study and Model Development

This page updated November 8, 2012

ARB Research Seminar

Friday, December 14, 2012
10:00 am, PST
Byron Sher Auditorium, Second Floor
1001 "I" Street, Sacramento

This event is being Webcast, click here to view
Webcast viewers: Please send your questions during broadcast to: auditorium@calepa.ca.gov
Presentation will be available at this link:

William P. L. Carter, Ph.D.
Air Pollution Research Center and the
College of Engineering-Center for Environmental Research and Technology
University of California, Riverside

An experimental and mechanism development study was carried out to enhance the recently developed SAPRC-11 gas phase aromatic mechanism so it can predict secondary organic aerosol (SOA) formation from the atmospheric reactions of aromatic hydrocarbons. This phase of the project covered dry conditions and 300K. A total of 158 dual reactor chamber experiments were carried out using the UCR-EPA environmental chamber, and their results were combined with previous data from this chamber to provide a database of 315 separate reactor irradiations for mechanism evaluation. A total of 14 representative aromatic compounds and 7 representative phenolic compounds were studied with varying reactant and NOx levels, and in some cases with different light sources and other added reactants. Methods were developed and evaluated to represent gas-particle partitioning, nucleation, and chamber effects when modeling the experiments. Alternative mechanisms were examined and SOA yield and gas-particle partitioning parameters were optimized to simulate the available chamber data. The model simulated most of the data without large biases but with larger run-to-run variability in model performance than observed in ozone mechanism evaluations, and potential evaluation problems were observed for some compounds. It is concluded that this new mechanism reflects the current state of the science.

William P. L. Carter, Ph.D., holds a joint emeritus appointment at the Air Pollution Research Center and the College of Engineering-Center for Environmental Research and Technology (CE-CERT) at the University of California, Riverside. Dr. Carter's research concerns the gas-phase atmospheric reactions of volatile organic compounds (VOCs) and the assessment of ozone and other impacts of VOCs in the atmosphere. This includes developing chemical mechanisms for airshed models, conducting environmental chamber experiments to evaluate and improve these mechanisms, and utilizing them in airshed models to develop ozone reactivity scales for VOCs. Chemical mechanisms he developed are used in airshed models for a number of research and regulatory applications. Ozone reactivity scales he developed have been incorporated into ARB’s VOC emissions control regulations.

For information on this Seminar please contact:
Ralph Propper at (916) 323-1535 or send email to: rpropper@arb.ca.gov

For information on this Series please contact:
Peter Mathews at (916) 323-8711 or send email to: pmathews@arb.ca.gov

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