A measurement and model study on ozone characteristics in marine air at a remote island station and its interaction with urban ozone air quality in Shanghai, China

Abstract

Abstract. To understand the characteristics and changes of baseline ozone (O3) in oceanic air in eastern China, a 6-year measurement of O3 concentration was conducted from 1 January 2012 to 15 September 2017 at a remote offshore station located on Sheshan Island (SSI) near the megacity of Shanghai. The observed monthly mean O3 concentrations at SSI ranged from 33.4 to 61.4 ppbv during the study period, which were about 80 % and 12 % higher, respectively, than those measured at downtown and rural sites in Shanghai. Compared to the remarkable O3 increases observed at urban and rural sites in Shanghai, observed O3 concentrations at SSI exhibited statistically insignificant increasing changes (1.12 ppbv yr−1, α>0.10) during the observation period, suggesting less impacts of anthropogenic emissions on O3 levels in oceanic air. In addition, an insignificant decreasing change (−0.72 ppbv yr−1, α>0.10) was detected in O3 concentrations at SSI in September and October when the influence of regional transport was minimum throughout the year, providing a good proxy to study the baseline oxidation capacity of the oceanic atmosphere. City plumes from Shanghai usually carried higher levels of NOx, resulting in decreased O3 concentrations at SSI during southwesterly and westerly winds. However, In MAM (March–May) and JJA (June–August), due to the enhanced production of oxygenated volatile organic compounds, O3 could be continuously produced during daytime in aged city plumes, resulting in elevated O3 concentrations transported to SSI. The impacts of the offshore O3 on O3 levels in Shanghai are quantified during an easterly wind dominant episode (1–30 September 2014) using the WRF-Chem model (Weather Research and Forecasting model coupled with Chemistry). Sensitivity results suggest that O3 in the oceanic air inflows can lead to 20 %–30 % increases in urban O3 concentrations, which should be crucially considered in dealing with urban O3 pollution in large coastal cities like Shanghai.

Response of the ozone-related health burden in Europe to changes in local anthropogenic emissions of ozone precursors

“…Thus, tracing the response of O 3 pollution to emission changes is of extraordinary importance for designing effective environmental policies. Approaches to identify which emissions contribute most to O 3 are mostly based on chemical transport models (CTMs), which either tag precursor emissions from particular source categories or regions [8,9], perturb certain emissions to quantify their contributions [10][11][12], or employ instrumented versions of the CTM to calculate first or second order O 3 sensitivities [13]. Such methods have been applied to investigate the response of O 3 -related health impacts to emission changes in previous studies [14].…”

Exploring ozone formation rules and concentration response to the change of precursors based on artificial neural network simulation in a typical industrial park

“…It is generally recognized that volatile organic compounds (VOCs) and nitrogen oxides (NO X ) are the two dominant precursors [ 4 ]. However, the secondary photochemical conversion of VOCs and NO X are nonlinear and influenced by several spatial-temporal heterogeneity factors [ 1 , 5 ], as well as complex affection from meteorological factors [ 6 , 7 ]. Consequently, the underlying mechanisms governing O 3 pollution remain unclear.…”

Meteorological factor contributions to the seesaw concentration pattern between PM2.5 and O3 in Shanghai

“…Thus, the increase in water vapor can lead to a decrease in surface ozone concentrations (Camalier et al, 2007;He et al, 2017).Pollutant distributions are strongly affected by the wind field (Chen et al, 2020). PM 2.5 concentrations typically decrease by an order of magnitude between polluted regions and the diluting background air, whereas for ozone concentrations may actually increase or decrease, affected by upwind regions (Jacob and Winner, 2009;Gu et al, 2020b). Precipitation decreases both PM 2.5 and O 3 concentrations via wet removal (Shan et al, 2008).…”