Size Distribution And Growth Characteristics Of Atmospheric Aerosols In High Latitude Regions Of Eastern China

In this study, the size distribution under different air mass sources and growth characteristics of atmospheric aerosols were analyzed by using the date of atmospheric aerosols, CCN, meteorological parameters and back trajectory data during the in-situ campaign in Tangkou of Huangshan from May to September,2011. The main research contents and conclusions are as follows:Particles in size range of0.01～0.5μm accounted for above99%of particles in size range of0.01～10μm. The atmospheric aerosol number concentration also lower when compared to parts of the cities, rural and mountain regions in China and abroad, which indicated a clean and less polluted background atmospheric environment in Tangkou during the observation.The sources of air mass significantly impacted on the aerosol number and size distribution. Our results showed that the size distribution of aerosol presented a unimodal with high concentration in accumulation model under the local air mass (LAM) sources. However, when the air mass form southwest (SWAM) of the observation site, the aerosol total number concentration was higher and also presented a unimodal distribution with the dominated fraction in Aitken nuclei model. In addition, a lower number concentration and bimodal distribution characteristics of the aerosol were presented when the air form northeast (NEAM) of the observation site.The CCN number was much higher in LAM and NEAM than in SWAM, the most possible reason might be the high concentration of the water vapor in these two types of air mass, under the high relative humidity and low temperature, aerosols were easy to activated as CCN. According to Hobbs’s research, an aged-continental and transitional type of CCN distribution were presented during LAM-NEAM and SWAM, respectively. A lower activation rate of aerosol presented in day and night during the SWAM, on the contrary, a lower activation rate presented during LAM and NEAM. Unexpectedly, the activation rate of aerosol was larger than1in the night when supersaturation beyond4%, which might largely influenced by the inaccuracy of the instrumental itself.There were several times of atmospheric nucleation events during the observation, the growth rate of ultrafine particles was about4.7±0.9nm/h, which was very close to the typical growth rate of particles in boundary layer around the world, the particles growth from10nm to60nm might last as long as more than10hours. The growth rate might be affected by the sources of air mass, according to our study, the growth rate of air mass came form mainland was lower than air mass came from sea. Under the stable meteorological conditions, the particle growth might be affected by pollutants nucleation form mainland air mass and hygroscopic growth form the mixed maritime-mainland air mass, the mechanism of new particle formation is still unclear and needs more researches in future.