Evolution of Aerosols in the Atmospheric Boundary Layer and Elevated Layers during a Severe, Persistent Haze Episode in a Central China Megacity

Aerosol vertical profiling is crucial to understand the formation mechanism and evolution processes of haze, which have not yet been comprehensively clarified. In this study, we investigated a severe, persistent haze event in Wuhan (30.5° N, 114.4° E), China during 5–18 January 2013 by use polarization lidar, Cimel sun photometer, meteorological datasets, hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model, focusing on time–height aerosols both atmospheric boundary layer (ABL) elevated layers. During period, particle depolarization ratio was 0.05 ± 0.02, fine mode fraction reached 0.91 0.03, indicating particles were rather spherical predominately submicron, that is, anthropogenic nature. Compared with clear columnar aerosol optical depth at 500 nm tripled 1.32 0.31, strongest enhancement concentration occurred from near ground an altitude 1.2 km period. The daytime distribution ABL exhibited distinct pattern under weather. Abundant accumulated below 0.5 morning hours due stable conditions, including strong surface-based inversion (4.4–8.1 °C), late development (from 1000–1100 LT) convective layer, weak wind (<4 m?s?1) lowermost troposphere. afternoon, improved ventilation delivered overall reduction but insufficient eliminate haze. Particularly, residual had 0.29–0.56. It influenced air quality indirectly weakening activities directly through fumigation process around noon, suggesting it may be important element aerosol–ABL interactions consecutive days Our lidar also captured presence layers (EALs) embodying regional/long-range transport. Most EALs observed subside <1.2 exacerbate pollution level. Backward analysis data revealed originated transport pollutants Sichuan Basin, China, dust deserts northwest. They estimated contribute ~19% aerosol-loading, pointing non-negligible role intense episode. results could benefit complete understanding weather forecasting control Wuhan.