Analysis of long-range transport effects on PM_2.5 during a short severe haze in Beijing, China

Comprehensively using Inverse Distance Weighted (IDW) analysis, Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, three-dimensional (3D) cluster analysis, Weight Potential Source Concentration Function (WPSCF) analysis and other statistic methods, we mainly studied about the spatio-temporal variation, long-range transport and potential source regions of PM_2.5 in Beijing during a short severe haze from Dec05 to Dec11, 2015. The results showed that the concentration of PM_2.5 decreased from south to north of Beijing. PM_2.5 accumulation in the short-severe haze had high correlation with calm and steady meteorological condition (high relative humidity (RH), low wind speed (WS), low boundary-layer temperature (BLT) and surface air pressure (SAP)). In addition, air-flow in different heights (500 m, 1500 m and 3000 m) had different effects on the haze episode and the air flows at 500 m had the greatest contribution of the air pollution. The potential sources were mainly from the desert in northwest of Beijing and the built-up areas in Jing-Jin-Ji zone. Higher WPSCF values (> 0.7) were mainly distributed in Hebei, west Shandong province (around 0.5) and south Tianjin (around 0.5).