Impact of boundary-layer anticyclonic weather system on regional air quality

Based on a Lagrangian particle dispersion model FLEXPART 3-D in conjunction with a Weather Research and Forecasting (WRF) model, this study analyzed the synoptic patterns of the three sections (i.e. front, center, and rear) of a slow-moving anticyclonic weather system that took place during April 22–30, 2002 in northern China. The impacts of anticyclone on regional air quality were also revealed through simulating the transport trajectories of PM10 particles in the anticyclone. The findings indicate that PM10 pollutant transport process within the anticyclone showed the following characteristics: (a) the frontal pressure field played a strong role in removing pollutants from a high concentration zone located before the front, (b) the central part of anticyclone with an evident isobaric pressure field tended to create a pollutant accumulation process, and (c) the rear of the anticyclone system with a southerly warmer advection in the pressure gradient zone formed a stable channel for transporting pollutants. By using air pressure data and PM10 concentration measurements, the quantitative relationship between pressure variability and PM10 variation in different sections of the anticyclone was established. A linear relationship was assumed between PM10 variation per unit area in the mixing layer and pressure variation within a time interval, and different sections of the anticyclone were associated with different linear regression equations. A parameter called PM10 variation rate was then put forward, which could be easily applied for regional air pollution control and management.