Abstract. Anthropogenic fossil fuel (FF) combustion, biomass burning (BB) and desert
dust are the main sources of air pollutants around the globe but are particularly
intensive and important for air quality in Asia in spring. In this study, we
investigate the vertical distribution, transport characteristics, source
contribution and meteorological feedback of these aerosols in a unique
pollution episode that occurred in eastern Asia based on various measurement data
and modeling methods. In this episode, the Yangtze River Delta (YRD) in
eastern China experienced persistent air pollution, dramatically changing
from secondary fine particulate pollution to dust pollution in late March
2015. The Eulerian and Lagrangian models were conducted to investigate the
vertical structure, transport characteristics and mechanisms of the
multi-scale, multisource and multiday air pollution episode. The regional
polluted continental aerosols mainly accumulated near the surface, mixed with
dust aerosol downwash from the upper planetary boundary layer (PBL) and
middle–lower troposphere (MLT), and further transported by large-scale cold
fronts and warm conveyor belts. BB smoke from Southeast Asia was transported
by westerlies around the altitude of 3 km from southern China, was further mixed
with dust and FF aerosols in eastern China and experienced long-range
transport over the Pacific. These pollutants could all be transported to the YRD
region and cause a structure of multilayer pollution there. These
pollutants could also cause significant feedback with MLT meteorology and
then enhance local anthropogenic pollution. This study highlights the
importance of intensive vertical measurement in eastern China and the
downwind Pacific Ocean and raises the need for quantitative understanding of
environmental and climate impacts of these pollution sources.