Abstract
Abstract. The ozone weekend effect (OWE) was first investigated in the metropolitan area of Beijing–Tianjin–Hebei (BTH), China, using in situ measurements from the Atmospheric Environment Monitoring Network from July 2009 to August 2011. The results indicate that there is an obvious weekly periodical variation in the surface ozone concentration. There is a lower ozone concentration from Wednesday to Friday (weekday) and a higher concentration from Saturday to Monday (weekend) at all the locations of the study. NOx also displays a weekly cycle, with the maximum level occurring on weekdays and the minimum level on weekends, especially later on Sunday night and early Monday morning. This pattern may be responsible for the higher concentration of ozone on weekends. Additionally, the vertical variations in O3 and NOx from the 8 m, 47 m, 120 m and 280 m observation platforms on the 325 m Beijing meteorological tower displayed obvious weekly cycles that corresponded to the surface results. A smaller decrease in volatile organic compounds (VOCs; using CO as a proxy) and much lower NOx concentrations on the weekend may lead to higher VOC / NOx ratio, which can enhance the ozone production efficiency in VOC-limited regime areas. Additionally, a clear weekly cycle in the fine aerosol concentration was observed, with maximum values occurring on weekdays and minimum values occurring on weekends. Higher concentrations of aerosol on weekdays can reduce the UV radiation flux by scattering or absorbing, which leads to a decrease in the ozone production efficiency. A significant weekly cycle in UV radiation, consistent with the aerosol concentration, was discovered at the Beijing meteorological tower site (BJT), validating the assumption. A comprehensive understanding of the ozone weekend effect in the BTH area can provide deep insights into controlling photochemical pollution.
Highlights
Surface ozone (O3), as a main secondary air pollutant, has caused great concern due to its adverse effects on human health and vegetation (NRC, 1991)
O3 is predominantly produced through the photochemical oxidation of non-methane volatile organic compounds (NMVOCs) and carbon monoxide (CO) in the presence of nitrogen oxides (Fishman and Crutzen, 1978; Seinfeld and Pandis, 1998)
The surface ozone concentration in urban areas tends to be higher on weekends than on weekdays despite the lower concentration of ozone precursors (NOx and volatile organic compounds (VOCs))
Summary
Surface ozone (O3), as a main secondary air pollutant, has caused great concern due to its adverse effects on human health and vegetation (NRC, 1991). The ozone weekend effect (OWE) is a phenomenon that was first reported in the 1970s (Cleveland et al, 1974; Lebron, 1975; Levitt and Chock, 1976; Karl, 1978). In this phenomenon, the surface ozone concentration in urban areas tends to be higher on weekends than on weekdays despite the lower concentration of ozone precursors (NOx and volatile organic compounds (VOCs)). An appropriate understanding of the OWE may provide insights into the effectiveness of control strategies for ozone pollution, because these plans typically focus on reducing the emission of ozone precursors. The size of thme peoainstusrteanmdsefnortsthoe fmNagnOit,udNe OofxO,WCEOat, ePacMh 1si0te,(apnadrtthieclbelusewliniethstaanedrsofo-r prdo2yv4inncaimal bicouendqauryi.valent diameters of less than 10 μm) and PM2.5 (particles with aerodynamic equivalent diameters of less than 2.5 μm) were recorded to study the causes of the OWE, in addition to relevant data for ultraviolet radiation that were collected at the Beijing meteorological tower site (BJT)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
