[Distribution Characteristics of Near Surface Ozone Volume Fraction in Shanxi Province Based on Atmospheric Composition Observation Network].

Based on the continuous data of O， NO， NO， and NO and the meteorological data from March 2019 to February 2020 at six atmospheric composition observation stations in Shanxi Province， the characteristics and influence factors of O volume fractions were studied using statistical analysis and backward trajectory analysis. The results showed that O volume fractions were generally higher from April to September and lower from October to the following March. During the study period， O pollution represented by （MDA8O）， i.e.， the maximum daily 8-h average of O volume fractions， was the most serious at the Jincheng and Linfen stations in the south of Shanxi， followed by that in the Wutaishan， Shuozhou， and Datong stations in the north， with the least pollution occurring at the Taiyuan station in the middle. There were differences between the urban and alpine stations， although their seasonal O volume fractions were both summer > spring > autumn > winter. O volume fractions at the urban station were usually lower than those at the alpine station； O at the urban station might have been influenced by photochemical reactions with precursor NO； however， this was not the main source of high O at the alpine station. The peak and valley values appeared at 15：00 and 06：00， respectively， at the urban station， whereas they appeared at 20：00 and 10：00， respectively， at the alpine station， representing diametrically opposite diurnal variation patterns. Further， the daily amplitude of O at the urban station was much larger than that at the alpine station. For urban stations specifically， temperature was the most important meteorological factor affecting O volume fraction， compared with sunlight hours， precipitation， and total cloud cover. The NO volume fraction in the daytime affected the daily amplitude of O； although the photochemical generation potential of O at the Taiyuan station was good， the O volume fractions were the lowest among urban stations due to strong NO titration. The higher O corresponded to lower NO in which NO was dominant， and the higher NO was largely composed of NO， under which conditions O would be depleted completely. The surface wind that affected O volume fractions of all stations primarily came from the southeast， south， and southwest， and specific wind speed led to the increase in O volume fraction. The geographical situation of the station would cause the difference in the transport of atmospheric pollutants， whereas the horizontal transmissions of high O from the North China Plain and Fenwei Plain were likely to be the common reason for the increase in O volume fraction in Shanxi.