Impact of planetary boundary layer structure on the formation and evolution of air-pollution episodes in Shenyang, Northeast China

Abstract The impact of the planetary boundary layer (PBL) structure on air pollution in Northeast China, where frequently experiences air pollution episodes in autumn and winter, is not well understood due to a lack of observations. In this study, four pollution episodes during autumn and winter of 2016 at Shenyang, a provincial capital city in Northeast China, were examined to investigate the linkage between the PBL structure and air pollution using meteorological sounding data and LiDAR-retrieved profiles of aerosol extinction coefficients. We also conducted a tracer simulation using the Weather Research and Forecasting model with Chemistry (WRF-Chem) to demonstrate the transport and vertical mixing of air pollutants in the PBL. The results indicated that a stable, moist and shallow surface layer ( −1 ) and high relative humidity (>80%) in the PBL enhanced the deterioration of air quality near the surface.