北京大气O3与NOx的变化特征

Characteristics of atmospheric O_3 and NO_x concentrations in the urban area

以2004年8月—2005年7月北京市区近地层大气中臭氧(O3)和氮氧化物(NOx)体积分数观测资料,研究了北京大气中O3和NOx体积分数的变化特征。研究表明:北京市O3体积分数较高,并呈季节性波动,大气光化学污染以夏季最为严重。受太阳紫外辐射和城市交通的影响,城市O3体积分数呈单峰型分布,并在午后15:00出现峰值,造成大气强氧化性。NO2的光解速率夏季最大,在正午出现日最大值。受城市车流量变化的影响,周末NOx体积分数高于工作日,O3体积分数周末与工作日白天差异较小,而夜晚O3体积分数工作日高于周末。

Based on the observational data of near surface O3 and NOx concentrations in the urban area of Beijing from August 2004 to July 2005, the variation characteristics of O3 and NOx concentrations were analyzed. The results showed that O3 pollution was very serious, and O3 concentrations fluctuated periodically .The photochemical pollution in Beijing was most serious in summer. Peak O3 concentrations in Beijing often appear about 15：00 in the early afternoon, which caused by＇solar radiation and the vehicular traffic. Strong oxidation capacity appears. The highest photolysis rate coefficient of NO2O3） appears in summer. The greatest J3 in daytime appears at noon. Owing to changes of traffic in urban, NOx concentrations on weekends were higher than weekdays. Variations of O3 concentrations in daytime in weekend were a little different from weekdays, but O3 concentrations in night on weekends were lower than weekdays.