Identification of the atmospheric boundary layer structure through vertical distribution of PM_2.5 obtained by unmanned aerial vehicle measurements

Variations in the atmospheric boundary layer (ABL) structure present a close relationship with the vertical diffusion of air pollutants. However, the effect of the ABL structure on the vertical distribution of air pollutants is rarely investigated in detail, especially through in-situ measurement. In this study, from November 26th to December 20th, 2017, an unmanned aerial vehicle (UAV) outfitted with sensors was used to monitor meteorological factors and pollutants concentrations (including PM_2.5, O_3, and BC) in the suburbs of Shanghai. According to the vertical profiles of PM_2.5 concentrations, the gradient and the lidar backscatter methods were used to determine the parameters of the ABL structure. Results indicate that the maximum height of the atmospheric boundary layer occurred at noon exceeding 1000 m, and the maximum thickness of the atmospheric entrainment layer occurred at twilight exceeding 360 m during the field campaign. Additionally, the relationships between the structure of ABL and pollutant concentrations were analyzed and quantified. In contrast to the height of the ABL, the concentrations of ground-level aerosol pollutants show a stronger correlation with the thickness of the atmospheric entrainment layer. It also confirms that the entrainment flux ratio was an important factor affecting ground-level ozone concentrations. In summary, the in-situ measurements can provide experimental support for modeling the ABL structure and provide insights for the control of aerosol pollution.