Rapid extreme particulate pollution during cold frontal passage over central China

Large-scale air activity is a key factor that deteriorates air quality in highly polluted regions, but how aerosol-meteorology interacts during cold frontal passage and how it feedbacks to the formation and removal of par-ticulate pollution is remained to be studied. This study utilizes observations and the coupled WRF-Chem model to explore the quick formation and removal of severe particulate pollution over central China. Parallel experiments were designed to study the influence of aerosol-meteorology interactions and wet scavenging effects. Results revealed a dynamic-driven enhancement followed by a thermodynamic-driven enhancement of the surface fine particulate pollution (PM2.5) in the pre-frontal zone. Under influence of the large-scale air activities, the pol-lutants were transported from the highly polluted adjacent regions to the local, and accumulated within a short time. The increase of the regional ambient aerosol reduced solar radiation that reaches the ground, and increased the stability of the boundary layer, thus further leading to an increase in surface particulate pollution. In the pre -frontal region, the increased ground PM2.5 concentration can be high up to 20 mu g/m3. Also, terrain played important role in the deterioration of the regional air quality by providing favorable environments to build up a pre-frontal dynamic structure and pollutant transport path.