The Case Analysis Of Beijing Heavy Pollution In Typical Haze

In recent years,with the continuous expansion of the scale of Beijing,pollution emissions continue to increase,the total amount of atmospheric pollution emissions far beyond the capacity of the environment,but the Beijing City terrain structure is special,is not conducive to the dilution and diffusion of pollutants,so in recent years the increasing number of the haze weather,the impact is also gradually increased,to daily life,transportation and human health has brought great negative impact.This paper analyzes the 2015~2016 annual Beijing haze pollution characteristics,and make a year back trajectory cluster analysis,which selected the typical heavy pollution haze,the typical case is used to analyze the data from the experimental observation,analysis of pollution characteristics and causes of pollution,the main results are as follows:(1)From September 2015 to August 2016 Beijing haze occurred 3891 hours hours,haze days 190 days.Among them,the November haze days up to 27 days,in July December,the time was 23 days,days of haze appeared at least in February,only 6 days.In addition,the frequency of dry haze was higher than that of wet haze.During the study period were AQI months more than 50,AQI and PM2.5 are basically the same trend,from September 2015 to December 2015 showed a rising trend,by January 2016,declined in February,the wave change trend then up and down,up and down.In summary,the air quality in Beijing during the study period was basically consistent with that observed in meteorology.(2)To the analysis of trajectory clustering in Beijing City,5 classes,and each class is calculated trajectories corresponding to a mean concentration of PM2.5,has a great influence of two kinds of track which from the western regions of Inner Mongolia and Hebei,Shandong,Henan border area of Beijing's air quality;the cleanest from North northwest track the air masses bring good weather to Beijing;using PSCF and WPSCF method in Beijing PM2.5 concentration was analyzed,the high value areas are mainly concentrated in Hebei,Shanxi and surrounding areas show that short distance transmission is the main cause of Beijing high concentration of PM2.5.(3)This paper do not use in the meteorology haze day and AQI as two reference index selection process of pollution,3 or more consecutive days of air quality index more than 100 days of haze selected for the haze of heavy pollution process,there are 18 heavy pollution haze process,and backtrajectory model to select the most pollution process 7 representative(winter)and pollution(summer 17 non heating period).(4)The typical pollution process 2 days ~12 months in November 26,2016 7 involving the entire eastern region,most areas of daily average concentration of PM2.5 is higher than that of 250 ug,M-3,Beijing area is more serious in scale,is a large,long time pollution weather process.The typical process of pollution on July 2,2016 to 12 area 17 light pollution to the wide and moderate pollution level pollution mainly relates to the Beijing Tianjin Hebei region,Ji'nan,Henan and other regions,develop moderate to severe pollution,pollution weather is a small,long time of the process.(5)During the heating period in winter,the visibility of was less than 2km during the period of pollution.The relative humidity is up to 88.9%,which promotes the formation of fine particulate matter.During the pollution,the wind speed is low,the static wind frequency is 18%,and the wind direction is southerly.During the process of pollution in non heating period in summer the average relative humidity of 51.6%,visibility is basically maintained at about 5Km,with a slight haze and mild haze;scale mainly for level 1 and level 2,corresponding to the 0.3~3.3m/s of the wind speed,the wind speed is relatively low,the dilution and diffusion ability is weak and the south wind near the pollutants,mainly.(6)Two typical pollution process in the vertical to the optical characteristic analysis,both extinction material in serious pollution,pollution is different,winter is accompanied by meteorological conditions and the change of the boundary layer height increases,pollution dispersed,and pollution is due to a process of summer rainfall will dispel pollution.In addition,in the process of pollution in winter,the atmospheric boundary layer height and PM2.5 had a significant inverse relation,and the pollution during the stable stratification;and the pollution process in the summer,the atmosphere in the serious pollution during the boundary layer height is very low,the atmospheric stratification is stable stratification,in slightly polluted period,but the concentration of PM2.5 and the height of the atmospheric boundary layer fluctuation has no significant correlation,the atmospheric stratification belongs to the unstable stratification.