使用宽范围粒径谱仪(WPS)对嘉兴市2015年5月1—31日10 nm—10μm的气溶胶粒径分布进行了测定,结合HYSPLIT轨迹模式的气团聚类分型结果,分析了不同类型气团下气溶胶数浓度和表面积浓度的日变化和粒径分布特征.结果表明,观测期间嘉兴市主要受5类气团控制,分别为海洋性气团(Type1,31%)、局地气团(Type2,32%)、西南内陆气团(Type3,25%)、海陆混合气团(Type4,8%)以及西北内陆气团(Type5,4%).气团类型对核模态(10—20 nm)和粗模态(1.0—10μm)粒子数浓度日变化的影响较大,其次是积聚模态(100—1000 nm)粒子,对爱根核模态(20—100 nm)粒子数浓度日变化的影响较小.不同类型气团下气溶胶数浓度谱分布均为单峰型分布,但是谱分布特征差异较大.不同类型气团下表面积浓度的日变化多为双峰型分布,峰值出现在07∶00—09∶00和17∶00—21∶00;气溶胶表面积浓度谱均为三峰型分布,峰值分别位于120—150 nm、500—700 nm和1.2—1.5μm,Type5气团下的表面积峰值浓度最小,Type3气团下的表面积峰值浓度最大.
The aerosol size distribution in the range of 10 nm-10 μm was measured in Jiaxing by Wide Range Particle Spectrometer (WPS) on May 1-31, 2015. The diurnal variation and size distribution of aerosol number concentration and surface area concentration impacted by different types of air mass were analyzed by using the back-trajectory model HYSPLIT. Results show that Jiaxing was controlled by five types of air mass during the observation period, including the maritime air mass (Typel, 31%), local air mass (Type2, 32%), the inland air mass from southwest (Type3, 25%), the mixture air mass (Type4, 8%) and the inland air mass from northwest (TypeS, 4%). The type of air mass had the largest strongest impact on the diurnal variation of aerosol number concentration in nuclear mode and coarse mode, followed by accumulation mode,and had the least impact on Aitken nuclei mode particles. The spectra distribution of aerosol number concentration was all unimodal, but showed large discrepancy among five types. The diurnal variation of aerosol surface area concentrations displayed bimodal distribution, with peaks at 07:00-09:00 and 17:00-21:00. The spectra distribution of aerosol surface area concentration was trimodal, with peaks at 120-150 nm, 500-700 nm and 1.2-1.5 μm, respectively, the peak value of which was the lowest under Type5 air mass and the largest under Type3 air mass.