Lidar- and UAV-Based Vertical Observation of Spring Ozone and Particulate Matter in Nanjing, China

The rapid urbanization in China is accompanied by increasingly serious air pollution. Particulate matter and ozone are the main air pollutants, and the study of their vertical distribution and correlation plays an important role in the synergistic air pollution control. In this study, we performed Lidar- and UAV-based observations in spring in Nanjing, China. The average concentrations of surface ozone and PM2.5 during the observation period are 87.78 mu g m(-3) and 43.48 mu g m(-3), respectively. Vertically, ozone reaches a maximum in the upper boundary layer, while the aerosol extinction coefficient decreases with height. Generally, ozone and aerosol are negatively correlated below 650 m. The correlation coefficient increases with altitude and reaches a maximum of 0.379 at 1875 m. Within the boundary layer, ozone and aerosols are negatively correlated on days with particulate pollution (PM2.5 > 35 mu g m(-3)), while on clean days they are positively correlated. Above the boundary layer, the correlation coefficient is usually positive, regardless of the presence of particulate pollution. The UAV study compensates for Lidar detections below 500 m. We found that ozone concentration is higher in the upper layers than in the near-surface layers, and that ozone depletion is faster in the near-surface layers after sunset.

Automated summary

The rapid urbanization in China has led to increasingly serious air pollution. In this study, observations using Lidar and UAV were conducted in Nanjing during spring to study the vertical distribution and correlation of ozone and particulate matter. The results showed that ozone concentration is highest in the upper boundary layer, while aerosol extinction coefficient decreases with height. Below 650 m, ozone and aerosol are negatively correlated, while above the boundary layer, they are usually positively correlated, regardless of the presence of particulate pollution.