Research On Aerosol Scattering And Absorption Characteristics In Xuzhou

Xuzhou,the central city of Huaihai Economic Zone,is a traditional energy city with serious air pollution.In this paper,the scattering and absorption characteristics of aerosols in Xuzhou area from 2014 to 2017 are observed and studied by using integrated turbidimeter and aethalometer.The results are as follows:1)The mean values of scattering coefficient,absorption coefficient and single scattering albedo during observation were 292.56±223.65Mm^-1,22.65±18.73Mm^-1 and 0.93±0.05,respectively,indicating that scattering particles dominated in Xuzhou.2)In terms of daily variation analysis,both scattering and absorption coefficients show a bimodal single valley distribution,and the single scattering albedo has a bimodal double valley distribution,which is related to atmospheric boundary layer height,traffic emissions and meteorological factors.The pollution day is higher than the clean day,which is related to the rate of secondary aerosol formation.The working day scattering absorption coefficient is higher than the non-working day,which is related to traffic flow and human activities.3)The maximum and minimum values of the monthly mean value of the scattering coefficient appear in January and September.The maximum and minimum values of the monthly mean value of the absorption coefficient appear in January and November,and the monthly average of the single scattering albedo is above 0.9.4)The seasonal average value of the scattering absorption coefficient is highest in winter and lowest in autumn.The seasonal mean values of single-scattering albedo are winter,autumn,summer and spring,from large to small,and the average of the four seasons is higher than 0.9.5)The high values of Xuzhou scattering and absorption coefficient are mainly derived from the dominant wind direction in each season,mainly from the southwest?SW?,southeast?SE?and northwest?NW?directions.The scattering and absorption coefficients are mainly concentrated in the range of 0²00 Mm^-1 and 0²0 Mm^-1 under the four seasons high wind speed?>3.3m/s?.The high values of scattering coefficient(>600Mm^-1)and absorption coefficient(>40Mm^-1)mainly occur at low and medium wind speeds ranging from 0 to 3.3m/s,indicating that high wind speeds are conducive to the dilution and diffusion of pollutants,and that pollutants are easy to accumulate at medium and low wind speeds.The high value of pollutants at high wind speed is mainly related to long-distance transportation.The high value of pollutants at medium and low wind speed is mainly affected by local and regional pollution sources.Aiming at the two high-altitude haze input events detected by lidar?MiniMPL?from January 1 to 10,2015,the total aerosol absorption optical depth?AAOD?inverted from solar photometer observation and the ground aerosol absorption characteristics estimated by black carbon meter observation were compared and analyzed.The sources and paths of high-altitude haze trans-regional transmission were obtained by using HYSPLIT backward trajectory model.Cluster analysis quantitatively studied the contribution to local absorption coefficient.The results show that:1)The absorptive optical thickness?AAOD?of aerosols in the whole atmosphere will increase when there are external pollutants transported.When the high-altitude aerosols reach the ground,the pollutants brought by them will make the absorption coefficient of aerosols on the ground increase sharply.The results show that most of the foreign pollutants are absorbed aerosols,which can easily affect local haze weather and atmospheric visibility.2)The air masses arriving in Xuzhou from January 3 to 4,2015 mainly come from Anhui,Henan and Hunan.Air mass 1,air mass 2 and air mass 3 all belong to low altitude moving air mass.Their trajectories are short and their movement speed is slow,which indicates that Xuzhou was mainly affected by the surrounding pollution sources during this period.The air masses arriving in Xuzhou from January 7 to 8,2015 mainly come from the northwest direction and are influenced by Hebei,Shanxi and Henan provinces.The air mass 1has a long trajectory and belongs to a fast moving air mass.Air mass 2 has short trajectory and slow motion,which is mainly affected by local pollution sources.The air mass 3 belongs to the low-altitude air mass,which is susceptible to the pollutants in the city along the way.The motion track is longer and the moving speed is faster.This indicates that Xuzhou was affected by long-distance pollutant transport and local pollution sources during this period.