资源环境科技发展态势分析平台

Profiles of the ozone (O-3) concentration and meteorological parameters were measured with tethered balloons at two rural sites (the Zhuozhou and Gucheng stations) in the summer of 2012 and 2013 to investigate the interaction of morning residual layer (RL) O-3 and mixing layer (ML) O-3. Results revealed that O-3 from the previous day or surrounding transport will be stored in the RL and made significant impact on surface O-3 via downward mixing during transition hours (06:00 LT-10:00 LT). More O-3 was stored in the RL, the higher base concentration for O-3 pollution was existed. Generally, the downward mixing and photochemical reaction jointly contribute to the surface O-3 variation and horizontal transport of O-3 will further enhance this impact. Sometimes, even though the meteorological condition is unchanged, surface O-3 concentration could still be gradually accumulated via O-3 carried over from the preceding day. Impact of this downward mixing process was usually the greatest from 8: 00-10: 00 LT. Concentration of the O-3 carried over from the previous day can be as high as 76.8 ppb. Compared with local photochemical production, the RL O-3 could contribute more than 50% to the surface O-3 during transition hours. As a result, morning RL O-3 significantly influence the ML O-3 in rural areas of the North China Plain. Understanding of this mechanism will contribute to the experiment study and the improvement of air quality model.