Analysis of Different-Scales Circulation Patterns and Boundary Layer Structure of PM2.5 Heavy Pollutions in Beijing during Winter

The most immediate external objective of urban heavy haze pollution incidents was the weather conditions in addition to the internal reason of emission sources. Based on horizonal and vertical particulate matter (PM) data, conventional and encryption automatic meterological station data, and wind profiler data, the analysis of the influence of changes of different scales circulation patterns and boundary layer structure on the formation, accumulation, and dissipation of heavy pollutions of PM2.5 in Beijing during 21-28 February 2013 was presented. The results showed that, under the control of low or high weak pressure, the gathering of the southwest local wind, southeast transport wind, and north mountain wind, with clockwise wind shears in boundary layer, tended to bring on growth spurts of fine PM. Otherwise, the main cause of long time and steady growth of pollutions was the control of uniform pressure and near-surface south transport wind with high-level steady northwest wind. In addition, the key meteorlogical factor was near-surface low wind, high humidity, and maintaining a temperature inversion to promote and sustain the growth of regional haze pollution. A northwest wind in front of high pressure was a direct external power to disperse pollutions.