The Cross-Border Transport of PM2.5 from the Southeast Asian Biomass Burning Emissions and Its Impact on Air Pollution in Yunnan Plateau, Southwest China

Southeast Asia is one of the largest biomass burning (BB) regions in world, and air pollutants generated by this BB have an important impact on pollution southern China. However, mechanism cross-border transport to neighboring yet be understood. Based MODIS remote sensing products conventional observation data meteorology environment, WRF-Chem FLEXPART-WRF models were used simulate a typical PM2.5 episode that occurred during 24–26 March 2017 analyze over Yunnan Plateau (YP) southwest During episode, conjunction with flourishing activities Indo-China Peninsula (ICP) Asia, driven southwesterly winds prevailing from ICP YP, was observed along pathway lifting plateau topography YP. proximity sources ICP, YP divided into source region (SR) receptor (RR) for transport, negative positive correlation coefficients (R) between concentrations wind speeds, respectively, presented, indicating different impacts emissions two regions. XSBN Kunming, representative SR RR sites border hinterland distinct mechanisms enhance pollution. The site mainly affected local accumulation stagnant meteorological conditions, whereas dominated regional strong vertical mixing. It revealed large contributions lift lower altitudes higher PM2.5. Moreover, decrease increase distance, reflecting role distance source–receptor areas change.