Measurements and modeling of urban secondary organic aerosol formation potential as a function of precursor volatility class in the Los Angeles area during summer 2022
Abstract. Urban secondary organic aerosol (SOA) contributes to degraded air quality which can affect human health. Improvements in Los Angeles (LA), CA air quality have mainly plateaued since 2010. In summer 2022, measurements were made to quantify the SOA formation potential (SOA-FP) in ambient LA air. Two oxidation flow reactors (OFRs) ingested ambient air: one was equipped with an electrically conductive polymer inlet that denuded lower volatility species, and the other was run without an inlet. This allowed the separate quantification of SOA-FP from higher vs. lower volatility precursors. To our knowledge these are the first direct measurements of these fractions. Measured ambient SOA was similar and total SOA-FP was lower in 2022 vs. 2010, consistent with higher ambient OH causing greater consumptions of SOA precursors in 2022. The dual-OFR measurements suggest ~31 % of the total SOA-FP is due to compounds with volatilities in the SVOC and lower IVOC ranges. Results are compared to two box models: one based on CRACMM and the other adapted from a recent Caltech publication. CRACMM predicted ambient OA well but underpredicted SOA-FP by about a factor of 2, while the Caltech model underestimated OA and overpredicted SOA-FP by a factor of 2.5. Our study finds terpenoids contribute to, but do not dominate, SOA-FP.
Authors
- Benjamin N. Murphy (ORCID: https://orcid.org/0000-0003-3542-5378)
- J. A. de Gouw (ORCID: https://orcid.org/0000-0002-0385-1826)
- Benjamin C. Schulze (ORCID: https://orcid.org/0000-0002-6405-8872)
- Havala O. T. Pye (ORCID: https://orcid.org/0000-0002-2014-2140)
- Douglas A. Day (ORCID: https://orcid.org/0000-0003-3213-4233)
- Melinda K. Schueneman (ORCID: https://orcid.org/0000-0003-4359-1472)
- Anne V. Handschy (ORCID: https://orcid.org/0000-0003-2537-0019)
- Pedro Campuzano‐Jost (ORCID: https://orcid.org/0000-0003-3930-010X)
- Andrew Ryan Jensen (ORCID: https://orcid.org/0000-0003-0238-2367)
- Kelley C. Barsanti (ORCID: https://orcid.org/0000-0002-6065-8643)
- T. Nash Skipper (ORCID: https://orcid.org/0000-0003-4953-8736)
- Afsara Tasnia (ORCID: https://orcid.org/0000-0002-3048-5083)
- Jose Luis Jimenez (ORCID: https://orcid.org/0000-0001-6203-1847)
- Dongwook Kim (ORCID: https://orcid.org/0000-0002-2172-3588)
- D. Sueper
- Seonsik Yun (ORCID: https://orcid.org/0009-0003-1513-9240)
- Melissa A. Ehrenfels
- Drew B. Blauth
Institutions
- University of California, Riverside (US)
- NSF National Center for Atmospheric Research (US)
- California Institute of Technology (US)
- Environmental Protection Agency (US)
- Norwegian Meteorological Institute (NO)
- Cooperative Institute for Research in Environmental Sciences (US)
- University of Colorado Boulder (US)
- Aerodyne Research (US)
- South Coast Air Quality Management District (US)
- Center for Environmental Research and Technology (US)
- Kalamazoo College (US)
Publication Details
- Journal
- Aerosol Research
- Published
- 2026-10-30
- DOI
- https://doi.org/10.5194/ar-4-517-2026
- Primary Topic
- Atmospheric chemistry and aerosols
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- National Science Foundation
- California Institute of Technology
- Resnick Sustainability Institute for Science, Energy and Sustainability, California Institute of Technology
- Cooperative Institute for Research in Environmental Sciences
- National Oceanic and Atmospheric Administration