Chemical Boundary Layer and Its Impact on Air Pollution in Northern China
Xin Huang, Jiantao Huang, Chuanhua Ren, Jiaping Wang, Hongyue Wang, Jiandong Wang, Hao Yu, Jing Chen, Jian Gao, Aijun Ding
Abstract
Planetary boundary layer (PBL) meteorology plays a vital role in air pollution, which has drawn increasing attention due to its adverse eco-environmental impacts. Although recent observational studies suggested the vertical heterogeneity of pollutants in the PBL, the overall picture illustrating the structure of the chemistry is still not fully understood, especially for polluted regions in China. Here, wintertime observations of main gaseous and particulate pollutants together with aerosol components and ground-based lidar remote sensing, as well as model simulations, are integrated to better understand the chemical process related to PBL evolution. We find that the turbulent motion does shape chemistry stratification in the PBL, reflected especially by a steep ozone drop near the surface due to a strong titration effect. Furthermore, enhanced secondary production, like sulfate and nitrate aerosols, in the upper PBL and residual layer substantially contributes to near-surface haze pollution through vertical mixing. This work sheds more light on the chemical PBL and highlights the importance of understanding pollution with a vertical perspective.