Study Of Aerosol Microphysical Characteristics And Hygroscopicity In Xi'An Area

Aerosol microphysical properties have important implications for the atmospheric physic-chemical processes.Aerosol microphysical parameters ch ange with different pollution conditions,and interact with meteorological conditions.They also affect the characteristics of atmospheric visibility and pollution index.In this paper,the aerosol m icrophysical properties and h ygroscopic properties in Xi'an is studied using the data m easured by the wide-range particle size spectrometer,visibility meter and meteorological observation system.The variation characteristics of aerosol microphysical parameters in Xi'an area studied by using particle size spectrometer data.The changes of aerosol particle size distribution before and after a haze process are studied.The aerosol particle size distribution under different pollution levels was compared and analyzed,and the diurnal variation information of number concentration was studied.The hygroscopic properties of aerosols in Xi'an area were also studied by particle size spectrometer and meteorological observation system data.The calculation method of aerosol complex refractive index was proposed,and the complex refractive index and radar ratio of aerosols under different pollution con ditions were calculated.The variation characteristics of aerosol hygroscopic growth factors were studied.The variation of lidar ratios at different pollution levels were studied.The influence of aerosol hygroscopicity on visibility was also given.The correlation between aerosol microphysical parameters,visibility and meteorological conditions was studied and analyzed.In order to study the correlation between low visibility and its influencing factors in more depth,the relative humidity and volume concentration values were segmented,and the correlation between visibility and volume concentration and relative humidity was studied.The analysis shows that the high aerosol volume concentration is the more critical influencing factor for low visibility in Xi'an.The relative humidity is usually between 65%and 90%in heavy haze days.