Constraining nucleation, condensation, and chemistry in oxidation flow reactors using size-distribution measurements and aerosol microphysical modeling

• Published in: Atmospheric chemistry and physics 2018-08, Vol.18 (16), p.12433-12460
• Main Authors: Hodshire, Anna L, Palm, Brett B, Alexander, M. Lizabeth, Bian, Qijing, Campuzano-Jost, Pedro, Cross, Eben S, Day, Douglas A, de Sá, Suzane S, Guenther, Alex B, Hansel, Armin, Hunter, James F, Jud, Werner, Karl, Thomas, Kim, Saewung, Kroll, Jesse H, Park, Jeong-Hoo, Peng, Zhe, Seco, Roger, Smith, James N, Jimenez, Jose L, Pierce, Jeffrey R
• Format: Article
• Language: English
• Subjects: Accommodation; Accommodation coefficient; Aerosols; Ageing; Aging; Atmospheric models; Atmospheric nucleation; Chemical evolution; Chemical properties; Computer simulation; Condensation; Condensation (Physics); Constants; Diffusion; Dye dispersion; Dynamics; Environmental aspects; Equivalence; Evolution; Fragmentation; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Isoprene; Meteorological research; Microphysics; Modelling; Monoterpenes; Natural history; Nucleation; Organic chemistry; Organic compounds; Oxidation; Oxidation-reduction reactions; Oxidizing agents; Particle diffusion; Particle formation; Particle size distribution; Rate constants; Reactors; Secondary aerosols; Size distribution; Studies; Sulfuric acid; Sulphuric acid; Terpenes; Uptake; Volatility
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-18-12433-2018

Oxidation flow reactors (OFRs) allow the concentration of a given atmospheric oxidant to be increased beyond ambient levels in order to study secondary organic aerosol (SOA) formation and aging over varying periods of equivalent aging by that oxidant. Previous studies have used these reactors to determine the bulk OA mass and chemical evolution. To our knowledge, no OFR study has focused on the interpretation of the evolving aerosol size distributions. In this study, we use size-distribution measurements of the OFR and an aerosol microphysics model to learn about size-dependent processes in the OFR. Specifically, we use OFR exposures between 0.09 and 0.9 equivalent days of OH aging from the 2011 BEACHON-RoMBAS and GoAmazon2014/5 field campaigns. We use simulations in the TOMAS (TwO-Moment Aerosol Sectional) microphysics box model to constrain the following parameters in the OFR: (1) the rate constant of gas-phase functionalization reactions of organic compounds with OH, (2) the rate constant of gas-phase fragmentation reactions of organic compounds with OH, (3) the reactive uptake coefficient for heterogeneous fragmentation reactions with OH, (4) the nucleation rate constants for three different nucleation schemes, and (5) an effective accommodation coefficient that accounts for possible particle diffusion limitations of particles larger than 60 nm in diameter.