Characteristics of chemical composition and role of meteorological factors during heavy aerosol pollution episodes in northern Beijing area in autumn and winter of 2015

AbstractHeavy aerosol pollution episodes (HPEs) usually start from late autumn and become more serious in winter in Beijing and its vicinity (BIV). In this study, we examine the reasons for the formation and change of HPEs in the areas of northern BIV. The size-resolved chemical components of PM1 and meteorological conditions were investigated during HPEs in autumn and winter of 2015. Stable regional atmosphere and higher atmospheric condensation processes associated with southerly and lower speed wind led to the formation of HPEs. After the start of these HPEs, the concentration of fine particles increased more than twice in several hours. ~80% of the ‘explosive’ growth in PM mass can be considered as a positive feedback of meteorological factors that come from even more stable atmosphere and larger condensation rate of water vapour, which was derived from the interaction between formed aerosol pollution and the meteorological factors within boundary layer. Nitrate was the largest fraction of PM1 in autu...