Vertical distribution characteristics of aerosol particles over the Guanzhong Plain

Haze pollution occurs frequently in Xi'an-centerd Guanzhong Plain (GZP) in winter. In this study, a vehicle-based lidar system was used for monitoring the vertical distribution of aerosol particulates during a typical winter haze episode over GZP. Fixed-point lidar observations were combined with field observations of particle charging in Xi'an city to investigate the distribution of atmospheric particles and the process of formation of particulate pollution. Mobile lidar observations were conducted over three navigation routes in Xi'an and its neighboring cities to investigate the origin and transport of aerosol particles, and meteorological interactions over GZP. The results demonstrated that local emissions were the main cause of near-surface particulate pollution. Fluctuations in humidity promoted particle charging and enhanced particle growth. Polluted dust particles entrained by air mass could be transported from the northwest to high-altitude areas of Xi'an. Mobile lidar observations showed that aerosol particles in the Xi'an-Xianyang area exhibited a clear vertically stratified structure under 1900 m height; there was only one aerosol layer concentrated within 900 m from the ground in Baoji and the near-ground extinction coefficient was relatively high. A larger aerosol optical depth (AOD) was observed in Xi'an-Xianyang than in Baoji, indicating that AOD could be affected by the elevated aerosol layers within the boundary layer. The combined methods of fixed and mobile lidar measurements, and satellite information can be applied in other regions and supply detailed information for air quality models. •Ground-based fixed and mobile lidar measurements integrated with satellite data were analyzed.•Vehicle-based mobile lidar system examined the transport and distribution of aerosol particles.•AOD could be affected by the presence of elevated aerosol layers within the boundary layer.