The Influence Of Meteorological Factors On Air Pollution In Beijing-Tianjin-Hebei Regions

By using NCEP daily reanalysis data from 1986 to 2015 and surface weather data of87 stations in Beijing-tianjin-hebei region over 1961~2016,and Lamb-Jenkinson objective classification method and statistical method,studing and determining the weather conditions and key meteorological factors that are favorable and unfavorable to regional air quality,establishing weather system type that is not conducive to the diffusion of pollution and the spread of pollution,as well as the main influencing factors of air pollution diffusion,and analyzing the frequency of annual change and seasonal change.Analysis of L-J classification results showed that:NE(11.11%),A(10.32%),S(7.94%)and E(7.14%),were the main circulation type of the beijing-tianjin-hebei region is not conducive to diffusion;A(26.00%),C(5.33%),AN(5.33%),and N(4.67%)as the main circulation types conducive to diffusion.The analysis in the last three decades indicates that type A can be regarded as the dominant circulation type of the beijing-tianjin-hebei region.It is also suggested that autumn air in this area is conducive to the diffusion of the dominant circulation.Both the NE and E types were presented in the summer as the turning point,with a low middle height on both sides,the least occurrence of the four types of circulation type in the S-type air pollution,and slightly higher frequency in spring.C-type circulation is the dominant circulation of the beijing-tianjin-hebei region in the summer.N-type circulation mainly occurs in spring and autumn.AN annular circulation mainly winter and spring.The weather that is not conducive to diffusion mainly occurs in the relatively straight autumn and winter of 500 hPa.The beijing-tianjin-hebei region is largely controlled by the westerly flow and the fluctuation is weak.And to spread the weather circulation through the dimensions increase,in addition to the cyclonic circulation type C controlled by 500 hpa trough,other type circulation are the tank after the northwest airflow control,wind is bigger,is advantageous to the weakened fog dissipation.From the characteristics of interannual evolution of the seven major circulation types,the AN,N,type A and NE fluctuation trend of fluctuations.The interannual variation was more severe than that of E,S and C;E,S and C have changed slowly in recent three years,and they are increasing year by year in recent years.