近年来，大气污染物排放大量增加，包括地面臭氧污染在内的空气污染备受关注。作为二次污染物的臭氧主要来自于高度非线性的对流层光化学过程，两大关键因素是臭氧前体物和太阳辐射（特别是紫外辐射）。目前大部分的研究工作主要基于地面观测。然而，臭氧前体物和紫外辐射有明显的垂直变化，从而使得臭氧光化学过程在垂直方向上存在着差异，而人类活动排放到边界层内的大量气溶胶通过对紫外辐射的影响又进一步增加了该问题的复杂性。因此，认识边界层臭氧光化学机制特别是气溶胶污染条件下的臭氧光化学，需要相关的垂直特征观测分析。 本项目计划以系留气艇为观测平台开展垂直观测，结合地面观测系统进行加强观测，获取臭氧及其前体物的垂直分布特征，分析边界层内臭氧光化学的垂直特性，评估臭氧前体物对臭氧产生的贡献在不同高度上的差异，在此基础上初步探讨气溶胶对臭氧光化学过程垂直特征的影响和由此带来的对地面臭氧污染过程的影响。

Great concerns have recently been raised about air pollution such as ozone pollution, due to the significant increase of air pollutant emissions. As a secondary gas pollutant, tropospheric ozone is mainly produced from the highly nonlinear photochemical process, in which ozone precursors and solar radiation (especially ultraviolet radiation) are the two critical factors. Current studies of the ozone problem are mostly based upon surface measurements. However, vertical distributions of ozone precursors and ultraviolet radiation could lead to differences in the vertical characteristics of ozone photochemistry. Analysis regarding such issues is further complicated by effects of anthropogenic aerosols emitted into the planetary boundary layer on ultraviolet radiation. Thus, vertical measurements of ozone and its precursors are of great importance to advancing our understanding of ozone photochemistry within the planetary boundary layer, especially under aerosol pollution conditions. An intensive field campaign will be carried out during this project, including vertical measurements of ozone and its precursors using a tethered balloon system, also together with in-situ surface measurements. Vertical distributions of ozone and its precursors will be obtained. The vertical characteristics of ozone photochemistry will be analyzed. The contributions of different ozone precursors to ozone photochemical production at different heights will be estimated. Impacts of aerosols on the vertical characteristics of ozone photochemistry and its influences on surface ozone pollution wil be briefly investigated.