Assessing Regional Model Predictions of Wintertime SOA from Aromatic Compounds and Monoterpenes with Precursor-specific Tracers

The Community Multiscale Air Quality (CMAQ) model, with modifications to track precursor-specific SOA, was applied to model SOA formation from aromatic compounds and monoterpenes in Shanghai in November 2018. The modeled total aromatic SOA showed a strong correlation with measured 2,3-dihydroxy-4-ox...

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Bibliographic Details
Published in:Aerosol and Air Quality Research 2021-12, Vol.21 (12), p.1-19+ap1-5-012
Main Authors: Zhang, Jie, He, Xiao, Gao, Yaqin, Zhu, Shuhui, Jing, Shengao, Wang, Hongli, Yu, Jian Zhen, Ying, Qi
Format: Article
Language:English
Subjects:
Acids
Aerosols
Air pollution
Air quality
Aromatic compounds
Chambers
Emissions
Experiments
Gases
Levulinic acid
Monoterpenes
Oxidation
Precursors
Smog
Toluene
Tracers
VOCs
Volatile organic compounds
α-Pinene
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Summary:The Community Multiscale Air Quality (CMAQ) model, with modifications to track precursor-specific SOA, was applied to model SOA formation from aromatic compounds and monoterpenes in Shanghai in November 2018. The modeled total aromatic SOA showed a strong correlation with measured 2,3-dihydroxy-4-oxopentanoic acid (DHOPA) concentrations in the ambient aerosols (R ＞ 0.5 for hourly data and R ＞ 0.75 for daily average data). The ratios of observed DHOPA and modeled aromatic SOA with all components included is around (0.5-1.6) × 10^(-3), lower than the commonly used ratio of 4 × 10^(-3) determined for toluene in a series of smog chamber experiments. This suggests that aromatic SOA could be underestimated when directly using the chamber-derived ratios. The predicted monoterpene SOA shows a stronger correlation with the sum of two α-pinene tracers (α-pinT), pinic acid and 3-MBTCA, with R ＞ 0.6 and R ＞ 0.8 for hourly and daily data, respectively. The α-pinT to modeled monoterpene SOA ratios are 0.13-0.25, which generally match the ratio of 0.168 ± 0.081 reported in chamber studies. However, since the current model does not treat α-pinene and its SOA explicitly, future modeling studies should include a more detailed treatment of monoterpene emissions and reactions to predict SOA from these important precursors and compare with the ambient precursor-specific SOA-tracers.
ISSN:1680-8584
2071-1409
DOI:10.4209/aaqr.210233