Most previous O 3 simulations were based only on gaseous phase photochemistry.However,some aerosol-related processes,namely,heterogeneous reactions occurring on the aerosol surface and photolysis rate alternated by aerosol radiative influence,may affect O 3 photochemistry under high aerosol loads.A three-dimensional air quality model,Models-3/Community Multi-scale Air Quality-Model of Aerosol Dynamics,Reaction,Ionization,and Dissolution,was employed to simulate the effects of the above-mentioned processes on O 3 formation under typical high O 3 episodes in Beijing during summer.Five heterogeneous reactions,i.e.,NO 2,NO 3,N 2 O 5,HO 2,and O 3,were individually investigated to elucidate their effects on O 3 formation.The results showed that the heterogeneous reactions significantly affected O 3 formation in the urban plume.NO 2 heterogeneous reaction increased O 3 to 90 ppb,while HO 2 heterogeneous reaction decreased O 3 to 33 ppb.In addition,O 3 heterogeneous loss decreased O 3 to 31 ppb.The effects of NO 2,NO 3,and N 2 O 5 heterogeneous reactions showed opposite O 3 concentration changes between the urban and extra-urban areas because of the response of the reactions to the two types of O 3 formation regimes.When the aerosol radiative influence was included,the photolysis rate decreased and O 3 decreased significantly to 73 ppb O 3.The two aerosol-related processes should be considered in the study of O 3 formation because high aerosol concentration is a ubiquitous phenomenon that affects the urban-and regional air quality in China.
