Reduced Aerosol Uptake of Hydroperoxyl Radical May Increase the Sensitivity of Ozone Production to Volatile Organic Compounds

A multiphase chemical kinetic box model (PKU-MARK) was constructed to numerically drive the hydroperoxyl radical (HO 2 ) uptake coefficients (γ HO 2 ) using observation data from a comprehensive summer field campaign in rural China. The associated multiphase chemistry mechanism of HO 2 uptake was investigated. The chemical and physical features of aerosol particles were explicitly considered in the simulations. The importance of transition metals in HO 2 heterogeneous processes was confirmed by a heterogeneous flux investigation. Heterogeneous processes were proposed to have impacts on the ozone sensitivity regime, which can be separated into either “nitrogen oxides (NO x ) limited” (peroxyl radical self-reaction dominates the chain termination step) or “volatile organic compounds (VOCs) limited” (the OH + NO 2 reaction dominates). In this study, while the HO 2 heterogeneous process could not change the ozone sensitivity regime classification in a single day, it could decrease net ozone production rates to 6 ppbV h –1, particularly in the morning of the “VOCs limited” period. The impacts of aerosols on ozone production sensitivity were further analyzed to demonstrate the potential tensions between particle and ozone control strategies in high-aerosol loading areas. Effective reduction of VOCs while applying the particle control strategy may be a viable solution that requires further investigation.