Radiative and heterogeneous chemical effects of aerosols on ozone and inorganic aerosols over East Asia.

Currently, many challenges are faced in simulating ozone(O 3 ), sulfate(SO 4 2 − ), and nitrate(NO 3 − ) concentrations over East Asia, particularly the overestimation of surface O 3 and NO 3 − concentrations and underestimation of the SO 4 2 − concentration during haze episodes. In this study, we examined the radiative and heterogeneous chemical effects of aerosols by incorporating recently reported mechanisms, including self-amplifying SO 4 2 − formation, dinitrogen pentoxide (N 2 O 5 ) hydrolysis, and a heterogeneous reaction converting gaseous nitric acid (HNO 3 ) to nitric oxide (NO x ), into a Nested Air Quality Prediction Modeling System. Uptakes by aerosols can be computed through a simple parameterization that is dependent on the aerosol core and shell species, shell thickness, and amount of aerosol liquid water. In this study, a 1-year simulation was conducted for 2013. The updated model successfully reproduced the seasonal and daily observations of O 3 , fine particulate matter, SO 4 2 − , and NO 3 − concentrations in East Asia. Our results revealed that heterogeneous reactions reduced more surface O 3 concentrations (10–20 ppbv) in the polluted regions of East China than did perturbations in photolysis frequencies from aerosols, effectively again improving the comparison between simulations and observations. Oxidation of SO 2 by NO 2 on wet aerosols significantly enhanced SO 4 2 − formation, with sulfate covering approximately ~ 30–60% of total sulfate concentrations in North China Plain during haze days in winter. The uptake of reactive nitrogen species on aerosols effectively reduced NO 3 − concentrations and successfully balanced the NO x /HNO 3 chemistry in the models. We recommended that larger reductions of gaseous precursors should be considered in China to achieve the national air quality objective. The results show that surface O 3 concentrations over East China will increase if the emission of aerosols is reduced without corresponding reductions in O 3 precursors. [ABSTRACT FROM AUTHOR]