Comprehensive study of regional haze in the North China Plain with synergistic measurement from multiple mobile vehicle-based lidars and a lidar network.

Recently, haze pollution has emerged as a regional characteristic that needs to be monitored and mitigated sensibly in China, particularly in the North China Plain (NCP). Clarifying the distribution and source characteristics of haze is necessary to better understand its formation mechanism on a regional scale. In this study, a comprehensive study of regional haze using synergistic measurement from multiple mobile vehicle-based lidars, a ground-based lidar network, and in suit instruments is presented. To investigate the distribution and source characteristics of regional haze in the NCP during the winter of 2017, simultaneous measurements of aerosol under different wind conditions are conducted. The regional distribution characteristics of the aerosol were observed using three sets of mobile vehicle-based lidars, and the source characteristics were achieved using an analysis of transport flux (with the ground-based lidar network and the WRF-Chem model). High aerosol extinction was observed on the southwest pathway under a southern wind. Backward trajectories also indicated that the air masses at 500 m were primarily from the southwest. The transport flux at the boundary of Beijing (BJ) and Baoding (BD) on the southwest pathway was calculated. Below 500 m, the transport flux from BD to BJ was positive under a southern wind and negative under a northern wind. In addition to the transport layer below 500 m, an upper transport layer was observed both on November 6, 2017 and January 15, 2018. The upper transport layer from 500 m to 1500 m on November 6, 2017 was obviously noticeable, which decreased dramatically with a maximum transport flux of 539.53 μg m2 s. The significant transport layer at 1250 m with a maximum flux of 614.93 μg m2 s was observed on January 15, 2018, while it had no impact on the ground because it had not yet fallen.