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Published May 20, 2010 | Supplemental Material + Published
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Organic aerosol components observed in Northern Hemispheric datasets from Aerosol Mass Spectrometry


In this study we compile and present results from the factor analysis of 43 Aerosol Mass Spectrometer (AMS) datasets (27 of the datasets are reanalyzed in this work). The components from all sites, when taken together, provide a holistic overview of Northern Hemisphere organic aerosol (OA) and its evolution in the atmosphere. At most sites, the OA can be separated into oxygenated OA (OOA), hydrocarbon-like OA (HOA), and sometimes other components such as biomass burning OA (BBOA). We focus on the OOA components in this work. In many analyses, the OOA can be further deconvolved into low-volatility OOA (LV-OOA) and semi-volatile OOA (SV-OOA). Differences in the mass spectra of these components are characterized in terms of the two main ions m/z 44 (CO₂⁺) and m/z 43 (mostly C₂H₃O⁺), which are used to develop a new mass spectral diagnostic for following the aging of OA components in the atmosphere. The LV-OOA component spectra have higher f₄₄ (ratio of m/z 44 to total signal in the component mass spectrum) and lower f₄₃ (ratio of m/z 43 to total signal in the component mass spectrum) than SV-OOA. A wide range of f44 and O:C ratios are observed for both LV-OOA (0.17±0.04, 0.73±0.14) and SV-OOA (0.07±0.04, 0.35±0.14) components, reflecting the fact that there is a continuum of OOA properties in ambient aerosol. The OOA components (OOA, LV-OOA, and SV-OOA) from all sites cluster within a well-defined triangular region in the f₄₄ vs. f₄₃ space, which can be used as a standardized means for comparing and characterizing any OOA components (laboratory or ambient) observed with the AMS. Examination of the OOA components in this triangular space indicates that OOA component spectra become increasingly similar to each other and to fulvic acid and HULIS sample spectra as f₄₄ (a surrogate for O:C and an indicator of photochemical aging) increases. This indicates that ambient OA converges towards highly aged LV-OOA with atmospheric oxidation. The common features of the transformation between SV-OOA and LV-OOA at multiple sites potentially enable a simplified description of the oxidation of OA in the atmosphere. Comparison of laboratory SOA data with ambient OOA indicates that laboratory SOA are more similar to SV-OOA and rarely become as oxidized as ambient LV-OOA, likely due to the higher loadings employed in the experiments and/or limited oxidant exposure in most chamber experiments.

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© Author(s) 2010. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 27 November 2009. Published in Atmos. Chem. Phys. Discuss.: 23 December 2009. Revised: 14 April 2010. Accepted: 29 April 2010. Published: 20 May 2010. Aerodyne Research acknowledges the following funding for various field campaigns: ICARTT (NOAA NA05OAR4310102); NEAQS (NOAA AB133R04SE0480, NOAA RA1330-02-SE-015O); MILARGO (DOE DE-FGOZO5ER63982, NSF ATM-0528170). Y. Rudich and J. L. Jimenez acknowledge the financial support of the USA-Israel bi-national science foundation (BSF grant #2008146). I. M. Ulbrich, K. S. Docherty, P. F. DeCarlo, and J. L. Jimenez are grateful for funding from NOAA NA08OAR4310565, NSF ATM-0919189 and DOE DEFG0208ER64627. Q. Zhang acknowledges the support from the Department of Energy's Atmospheric Science Program (Office of Science, BER), Grant no. DEFG02-08ER64627. The authors would like to acknowledge U. Baltensperger, P. J. Ziemann, and L. M. Russell for helpful discussions. We acknowledge the contributions of the following individuals to recently published datasets included in Lanz et al. (2009): Crete (G. J. Engelhart, C. Mohr, and E. Kostenidou); Grenoble (O. Favez, C. George, and B. D'Anna); Rhine Valley (C. Mohr and S. Weimer). We also thank the many other research groups and individuals who contributed datasets included in this work (individual publications are acknowledged in the Tables S1 and S2 in the supplementary material: http://www.atmos-chem-phys.net/10/4625/2010/ acp-10-4625-2010-supplement.pdf. Edited by: T. Hoffmann.

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Published - Ng2010p10458Atmos_Chem_Phys.pdf

Supplemental Material - acp-10-4625-2010-supplement.pdf


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