Research On Aerosol Hygroscopic Growth Characteristics Based On Meteorological Observations

The paper was funded by National Basic Research Program of China(Grant 2016YFC0200404),the National Natural Science Foundation of China(Grant 41571347),the National Natural Science Foundation of China(Grant 41471305),the Education department of Sichuan Province Innovation team(Grant 41471305).The hygroscopic growth of aerosol particles has great influence on regional environment,meteorology and radiation budget.However,accurate observation of aerosol hygroscopic characteristics has important implications for describes aerosol hygroscopicity,research the effects to climatic environment and expand applications of satellite aerosol product.This study presents a method to estimate aerosol hygroscopic growth by integrating in situ meteorological and air quality data(visibility,humidity and PM2.5).There are mainly three parts of work that have been conducted in this study:Firstly,The temporal and spatial variations of aerosol hygroscopicity at three different sites in Zhejiang,namely Hemu in Hangzhou(an urbanized site),Shiyan in Quzhou(a clean inland site),and Ouhai in Wenzhou(a coastal site).Ouhai exhibits the highest hygroscopic growth ability,while Hemu,which lies in the central Yangtze River Delta(YRD)region,shows the moderate hygroscopic growth.Compared to the other two sites,Shiyan has less hygroscopic growth during most time within a year.The research on this issue in Hebei reported similar findings.Qinhuangdao exhibits the highest hygroscopic growth ability,while Zhangjiakou,shows the moderate hygroscopic growth.Compared to the other two sites,Xingtai which lies in the central North China Plain region,has less hygroscopic growth during most time within a year.The aerosol particles near coastal sites,Sea salt which is the highest component of PM2.5 has the highest proportion.It's weak Moisture absorption capacity in inland industrial cities which has less sea salt aerosols and more black carbon aerosols.Secondly,the method of estimating and fitting approaches were optimized,the 36 hours' backward trajectory air mass from Environmental Monitoring Station of Ouhai Wenzhou to station of Lichang Qinhuangdao was calculated per hour HYSPLIT.Backward trajectories classified through cluster analysis indicate that the difference imbedded in air mass of diverse types can change local aerosol constitution.The hygroscopic growth capabilities can be changed subsequently,and the backward trajectory model supports evidence for aerosol classification.Given the aerosol compounds of RAMS-CAMQ simulations,the classification was conducted in a regional scale to obtain results regarding more accurate regional hygroscopic growth properties.Nonetheless investigations infer that current model's spatial resolution is not supportable for hourly observation,the National Component Observation Net is under construction and in virtue of treatments like improved assimilation technique,the application in near future is promising.The third part Thirdly,is the appliance based on the hydroscopic properties of local aerosols have been applied in satellite retrieval of surface PM2.5.The near-ground dry optical extinction coefficients could be obtained by calculating the hydroscopic growth factor to correct the aerosol extinction coefficients under practical humid conditions.In comparison with synchronized observed PM2.5 mass density,the latter measurements could be optimized significantly in Jiangsu-Zhejiang and Hebei area.In experiments,hourly PM2.5 spatial distribution can be retrieved through physical correction according to Himawari satellite,in-situ stations and meteorological observations in Beijing-Tianjin-Hebei region.This approach proposed in this study is capable of describing the aerosol hydroscopic growth properties in a large-scale of spatiotemporal range precisely.It is a supplement for accurate observations,and it is promising for correction of nationwide hourly estimation of near-ground density of particulate matters.