Evolution of boundary layer ozone in Shijiazhuang, a suburban site on the North China Plain

The structure of the boundary layer affects the evolution of ozone (O-3), and research into this structure will provide important insights for understanding photochemical pollution. In this study, we conducted a one-month observation (from June 15 to July 14, 2016) of the boundary layer meteorological factors as well as O-3 and its precursors in Luancheng County, Shijiazhuang (37 degrees 53'N, 114 degrees 38'E). Our research showed that photochemical pollution in Shijiazhuang is serious, and the mean hourly maximum and mean 8-hr maximum O-3 concentrations are 97.9 +/- 26.1 and 84.4 +/- 22.4 ppbV, respectively. Meteorological factors play a significant role in the formation of O-3. High temperatures and southeasterly winds lead to elevated O-3 values, and at moderate relative humidity (40%-50%) and medium boundary layer heights (1200-1500 m), O-3 production sensitivity occurred in the transitional region between volatile organic compounds (VOC) and nitrogen oxides (NOx) limitations, and the O-3 concentration was the highest. The vertical profiles of O-3 were also measured by a tethered balloon. The results showed that a large amount of O-3 was stored in the residual layer, and the concentration was positively correlated with the O-3 concentration measured the previous day. During the daytime of the following day, the contribution of O-3 stored in the residual layer to the boundary layer reached 27% +/- 7% on average. (c) 2019 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.