Atmos. Chem. Phys. Discuss., 9, 6739-6785, 2009
www.atmos-chem-phys-discuss.net/9/6739/2009/
doi:10.5194/acpd-9-6739-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site
J. G. Slowik1,3, A. Vlasenko1,3, M. McGuire2,3, G. J. Evans2,3, and J. P. D. Abbatt1,3
1Department of Chemistry, University of Toronto, Toronto, Canada
2Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Canada
3Southern Ontario Centre for Atmospheric Aerosol Research, University of Toronto, Toronto, Canada

Abstract. During the winter component of the SPORT (Seasonal Particle Observations in the Region of Toronto) field campaign, particulate non-refractory chemical composition and concentration of selected volatile organic compounds (VOCs) were measured by an Aerodyne time-of-flight aerosol mass spectrometer (AMS) and a proton transfer reaction-mass spectrometer (PTR-MS), respectively. Sampling was performed in downtown Toronto ~15 m from a major road. The mass spectra from the AMS and PTR-MS were combined into a unified dataset, which was analyzed using positive matrix factorization (PMF). The two instruments were given equal weight in the PMF analysis by application of a scaling factor to the uncertainties of each instrument. A residual based metric, Δesc, was used to evaluate the relative weight. The PMF analysis yielded a 5-factor solution that included factors characteristic of regional transport, local traffic emissions, charbroiling, and oxidative processing. The unified dataset provides information on particle and VOC sources and atmospheric processing that cannot be obtained from the datasets of the individual instruments, such as apportionment of oxygenated VOCs to direct emission sources vs. secondary reaction products, improved correlation of oxygenated aerosol factors with photochemical age, and increased detail regarding the composition of oxygenated organic aerosol factors. This analysis represents the first application of PMF to a unified AMS/PTR-MS dataset.

Citation: Slowik, J. G., Vlasenko, A., McGuire, M., Evans, G. J., and Abbatt, J. P. D.: Simultaneous factor analysis of organic particle and gas mass spectra: AMS and PTR-MS measurements at an urban site, Atmos. Chem. Phys. Discuss., 9, 6739-6785, doi:10.5194/acpd-9-6739-2009, 2009.
 
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