Preprints
https://doi.org/10.5194/acp-2021-1002
https://doi.org/10.5194/acp-2021-1002
 
13 Jan 2022
13 Jan 2022
Status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

Secondary Organic Aerosol Formation via Multiphase Reaction of Hydrocarbons in Urban Atmospheres Using the CAMx Model Integrated with the UNIPAR model

Zechen Yu1, Myoseon Jang1, Soontae Kim2, Kyuwon Son2, Sanghee Han1, Azad Madhu1, and Jinsoo Park3 Zechen Yu et al.
  • 1Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
  • 2Department of Environmental and Safety Engineering, Ajou University, Suwon, South Korea
  • 3Air Quality Research Division, National Institute of Environmental Research, Environmental Research Complex, Incheon, South Korea

Abstract. The prediction of Secondary Organic Aerosol (SOA) in regional scales is traditionally performed by using gas-particle partitioning models. In the presence of inorganic salted wet aerosols, aqueous reactions of semivolatile organic compounds can also significantly contribute to SOA formation. The UNIfied Partitioning-Aerosol phase Reaction (UNIPAR) model utilizes explicit gas chemistry to better predict SOA mass from multiphase reactions. In this work, the UNIPAR model was incorporated with the Comprehensive Air Quality Model with Extensions (CAMx) to predict the ambient concentration of organic matter (OM) in urban atmospheres during the Korean-United States Air Quality (2016 KORUS-AQ) campaign. The SOA mass predicted with the CAMx-UNIPAR model changed with varying levels of humidity and emissions and in turn, has the potential to improve the accuracy of OM simulations. The CAMx-UNIPAR model significantly improved the simulation of SOA formation under the wet condition, which often occurred during the KORUS-AQ campaign, through the consideration of aqueous reactions of reactive organic species and gas-aqueous partitioning. The contribution of aromatic SOA to total OM was significant during the low-level transport/haze period (24–31 May 2016) because aromatic oxygenated products are hydrophilic and reactive in aqueous aerosols. The OM mass predicted with the CAMx-UNIPAR model was compared with that predicted with the CAMx model integrated with the conventional two product model (SOAP). Based on estimated statistical parameters to predict OM mass, the performance of CAMx-UNIPAR was noticeably better than the conventional CAMx model although both SOA models underestimated OM compared to observed values, possibly due to missing precursor hydrocarbons such as sesquiterpenes, alkanes, and intermediate VOCs. The CAMx-UNIPAR model simulation suggested that in the urban areas of South Korea, terpene and anthropogenic emissions significantly contribute to SOA formation while isoprene SOA minimally impacts SOA formation.

Zechen Yu et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-1002', Anonymous Referee #1, 28 Feb 2022
    • AC1: 'Reply on RC1', Myoseon Jang, 18 Apr 2022
  • RC2: 'Comment on acp-2021-1002', Anonymous Referee #2, 23 Mar 2022
    • AC2: 'Reply on RC2', Myoseon Jang, 18 Apr 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-1002', Anonymous Referee #1, 28 Feb 2022
    • AC1: 'Reply on RC1', Myoseon Jang, 18 Apr 2022
  • RC2: 'Comment on acp-2021-1002', Anonymous Referee #2, 23 Mar 2022
    • AC2: 'Reply on RC2', Myoseon Jang, 18 Apr 2022

Zechen Yu et al.

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Short summary
The UNIPAR model was incorporated with the CAMx model to predict the ambient concentration of organic matter in urban atmospheres during the KORUS-AQ campaign. The CAMx-UNIPAR model significantly improved the simulation of SOA formation under the wet aerosol condition through the consideration of aqueous reactions of reactive organic species and gas-aqueous partitioning into the wet inorganic aerosol.
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