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Published March 7, 2014 | Supplemental Material + Published
Journal Article Open

Emission factor ratios, SOA mass yields, and the impact of vehicular emissions on SOA formation


The underprediction of ambient secondary organic aerosol (SOA) levels by current atmospheric models in urban areas is well established, yet the cause of this underprediction remains elusive. Likewise, the relative contribution of emissions from gasoline- and diesel-fueled vehicles to the formation of SOA is generally unresolved. We investigate the source of these two discrepancies using data from the 2010 CalNex experiment carried out in the Los Angeles Basin (Ryerson et al., 2013). Specifically, we use gas-phase organic mass (GPOM) and CO emission factors in conjunction with measured enhancements in oxygenated organic aerosol (OOA) relative to CO to quantify the significant lack of closure between expected and observed organic aerosol concentrations attributable to fossil-fuel emissions. Two possible conclusions emerge from the analysis to yield consistency with the ambient data: (1) vehicular emissions are not a dominant source of anthropogenic fossil SOA in the Los Angeles Basin, or (2) the ambient SOA mass yields used to determine the SOA formation potential of vehicular emissions are substantially higher than those derived from laboratory chamber studies.

Additional Information

© Author(s) 2014. CC Attribution 3.0 License. Received: 17 September 2013. Published in Atmos. Chem. Phys. Discuss.: 28 October 2013. Revised: 29 January 2014. Accepted: 1 February 2014. Published: 7 March 2014. Published by Copernicus Publications on behalf of the European Geosciences Union. The authors would like to thank R. Bahreini, D. Gentner, A. Chan, A. Goldstein, and two anonymous reviewers for providing valuable comments. This study was supported by NOAA Climate Program Office's AC4 program, award no. NA13OAR4310058. P. L. Hayes and J. L. Jimenez thank CARB 08-309 and 11-305, DOE (BER/ASR) DE-SC0006035, and a CIRES Visiting Fellowship. Edited by: S. A. Nizkorodov

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Supplemental Material - acp-14-2383-2014.xml


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