Abstract:In this paper, the correlation between air pollution and meteorological elements and the configuration of high- and low-altitude weather systems in Jinan City is discussed, a synoptic conceptual model of Jinan air pollution is formed, and the effects of cold air processes of different intensities on the generation and elimination of air pollutants in Jinan City are studied. The results show that during 2016-2018 more than 75% of PM2.5 pollution episodes in Jinan City occurred in the surface uniform pressure field. If the occurrence probability of each weather pattern was equal, the surface weather pattern with the highest occurrence probability of pollution episodes was the inverted trough pattern (>55%), followed by the uniform pressure field pattern (26.8%). Moreover, there was a more than 25% occurrence probability of PM2.5 pollution when the 500 hPa circulation was controlled by such weather systems, i.e., the ridge, straight westerlies, anticyclone, behind the trough and in front of the trough. The circulation configuration at upper and lower levels with the greatest probability of PM2.5 pollution (>50%) in Jinan City was the type of the surface inverted trough and behind the upper-level trough, followed by the type of the surface inverted trough and the upper-level straight westerlies, and the type of the surface uniform pressure field and behind the upper-level trough. For the average, the mixed layer height was below 1000 m during PM2.5 pollution episodes and was less than 800 m under heavy pollution. During pollution periods, the average relative humidity is 65%±20%, and the average temperature was 6℃±1℃. The effect of cold air with different intensities on the pollutant episodes was complex. The stronger cold air (ΔT24 h>4.3℃, Δp24 h>4.74 hPa) with a certain duration, such as the northerly wind greater than 3.5 m·s-1 lasting more than 9.6 h, can remove pollutants completely. The slightly weaker cold air may be beneficial to reduce pollutant concentration. However, the weak cold air with a lower northerly wind speed may instead increase the pollutant concentration due to the transport of pollutants.