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Published August 13, 2015 | Published + Supplemental Material
Journal Article Open

Multi-generational oxidation model to simulate secondary organic aerosol in a 3-D air quality model


Multi-generational gas-phase oxidation of organic vapors can influence the abundance, composition and properties of secondary organic aerosol (SOA). Only recently have SOA models been developed that explicitly represent multi-generational SOA formation. In this work, we integrated the statistical oxidation model (SOM) into SAPRC-11 to simulate the multi-generational oxidation and gas/particle partitioning of SOA in the regional UCD/CIT (University of California, Davis/California Institute of Technology) air quality model. In the SOM, evolution of organic vapors by reaction with the hydroxyl radical is defined by (1) the number of oxygen atoms added per reaction, (2) the decrease in volatility upon addition of an oxygen atom and (3) the probability that a given reaction leads to fragmentation of the organic molecule. These SOM parameter values were fit to laboratory smog chamber data for each precursor/compound class. SOM was installed in the UCD/CIT model, which simulated air quality over 2-week periods in the South Coast Air Basin of California and the eastern United States. For the regions and episodes tested, the two-product SOA model and SOM produce similar SOA concentrations but a modestly different SOA chemical composition. Predictions of the oxygen-to-carbon ratio qualitatively agree with those measured globally using aerosol mass spectrometers. Overall, the implementation of the SOM in a 3-D model provides a comprehensive framework to simulate the atmospheric evolution of organic aerosol.

Additional Information

© 2015 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 4 February 2015 – Published in Geosci. Model Dev. Discuss.: 20 February 2015; Revised: 22 May 2015 – Accepted: 15 July 2015 – Published: 13 August 2015. The authors thank William Carter for useful discussions regarding SAPRC-11. This work was supported by the California Air Resources Board under contract 12-312. Although this work was funded by the CARB, the statements and conclusions are those of the authors and not necessarily those of the CARB.

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Published - gmd-8-2553-2015.pdf

Supplemental Material - gmd-8-2553-2015-supplement.pdf


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