In this study,the sounding data in the atmospheric boundary layer from 14 December 2016 to 4 January 2017 at the national climate observatory in Shou County,Anhui Province were used in conjunction with the meteorological data from conventional ground stations,pollutant concentration data and synoptic charts,to analyze the accumulation and removal processes of two heavy pollution events in this area.The analysis revealed the following key points.First,both heavy pollution episodes originated under stagnant atmospheric conditions unfavorable for diffusion (such as surface wind speed less than 3 m/s,and high relative humidity of greater than 80%),and were later alleviated by strong wind,precipitation and other favorable conditions for diffusion and deposition.Second,in terms of weather conditions,the high and low stratifications were stable during the accumulation of heavy pollution,and the lower layer was in the wet area,which was mostly controlled by warm tongue or accompanied by warm advection.At the same time,regional transport of pollutants was present.During the first heavy pollution removal,the weather control system in Shou County gradually changed to low pressure,and the lower layer was mostly east wind,with precipitation.The second process was caused by wet deposition of fog and removal of inversion layer.Finally,during the accumulation period of heavy pollution,the boundary layer height was low and the maximum height was only 500 m,which limited the vertical diffusion range of pollutants,thereby affecting the local pollutant concentration.Inversion occurred frequently during heavy pollution,and the surface layer inversion mainly occurred at night and early morning,with the inversion intensity reaching 3℃/(100 m).The pollutants accumulated in the lower layer of inversion and beaneath it.