Abstract: Based on near-surface meteorological and environmental observation data,vertical profiles of meteorological parameters,and reanalysis data in Shenyang,Liaoning province,the multi-scale meteorological conditions of aerosol pollution during the same period of the National Winter Games of China in the past five years (from January 10 to the end of February in 2021-2025) were analyzed.The objective synoptic classification method was used to reveal the large-scale synoptic patterns on heavy pollution and clean days.In combination with vertical profiles of meteorological parameters,the impact of atmospheric boundary layer structure on aerosol pollution under specific synoptic circulation was further investigated.The results indicate that aerosol pollution in the Shenyang is usually related to warm and moist conditions and weak wind near the surface.Heavy aerosol pollution tends to occur in the presence of three synoptic patterns at 850 hPa,including the uniform pressure pattern,the southern high pressure pattern,and the northeast low pressure pattern,with prevailing westerly winds.Among which,the average PM_2.5 concentration is highest in the presence of the second synoptic pattern.When there is a strong high-pressure system over the northern China at 850 hPa,the warming process occurs in the upper-level atmosphere of Shenyang due to the influence of warm westerly air flows,resulting in an increase in thermal stability in the lower troposphere,suppressing the development of the boundary layer and the vertical diffusion of pollutants.At the same time,pollutants and water vapor from upstream areas can be transported to Shenyang over long distances,exacerbating the pollution level.Therefore,under the unfavorable high-altitude synoptic situations,jointly efforts to reduce local emissions in Shenyang,it is also necessary to consider implementing coordinated emission reduction measures in upstream areas.