华东高海拔地区夏季气溶胶数浓度及谱分布特征

摘要

利用2014年7月黄山光明顶观测获得的气溶胶数浓度、气溶胶数谱数据,对黄山夏季气溶胶数浓度及谱分布特征进行分析,并在此基础上对气溶胶数谱进行了对数正态分布拟合.研究结果表明:黄山夏季气溶胶平均数浓度约为3 518.27 cm-3,主要集中在爱根核模态;气溶胶平均数浓度日变化呈双峰分布,峰值浓度的出现伴随着小粒子的增多.气溶胶数浓度与相对湿度和风速成负相关,高浓度的气溶胶多出现在较弱的东南风时;积聚模态气溶胶数浓度受风向影响显著.不同气团背景下气溶胶数谱差异集中在小于100 nm和500～1 000 nm粒径范围.爱根核模态气溶胶在高湿的西南气团影响下数浓度最低、谱较窄,而高温、低湿的东南气团对应的气溶胶数浓度最高、谱最宽,北方气团对应的气溶胶数浓度和谱宽居中;500～1 000 nm粒径范围气溶胶数谱分布特征与之相反.不同背景的气溶胶数谱和体积谱均可采用爱根模态、积聚模态l和积聚模态2三个模态进行对数正态分布拟合,但不同气团背景下的各模态谱型参数差异较大.%By analyzing the aerosol number concentration and the size distribution observed in July 2014 at Mt.Huang,the characteristics of aerosol distribution at Mt.Huang in summer were analyzed.On this basis,log-normal fitting were performed on aerosol size distribution.The results show that the average aerosol number concentration at Mt.Huang is about 3 518.27 cm-3.The aerosol number concentration is mainly concentrated in Aitken mode.The daily variation of aerosol average concentration showed a bimodal distribution,and the peak concentration was ac companied by the increase of small particles.The aerosol number concentration was negatively correlated with relative humidity and wind speed,and high aerosol number concentration usually occurred under weak southeastern wind condition.The aerosol number concentration in the accumulation mode was obviously influenced by wind direction.With the effect of different air masses,the difference of aerosol number distribution mainly existed in the particle size of less than 100 nm and between 500 and 1 000 nm.Under the southwest air mass with high humidity,there appeared the highest aerosol number concentration and the narrowest size distribution in Aitken mode.However,under the southeast air mass with high temperature and low humidity,there appeared the lowest aerosol number concentration and the widest size distribution.Aerosol number concentration and spectral width corresponding to northern air mass were in medium level.The size distribution characteristics of aerosol ranging from 500 to 1 000 nm were contrary to those in Aitken mode.The aerosol size distribution and volume distribution under different backgrounds can all be fitted to a log-normal distribution by using the three modes of Aitken mode,accumulation mode 1 and accumulation mode 2,but the aerosol number concentration spectral parameters under different air masses were quite different.