南京北郊云凝结核活化特征观测及闭合研究

采用SMPS-CCNC联用全扫描的方法，于2016年11~12月在南京北郊地区，对8.2~346nm粒径段的气溶胶粒子展开了粒径分辨的云凝结核（CCN）活化特征观测，并利用6种参数化方法对CCN数浓度进行了闭合研究.结果表明本次观测中南京地区的气溶胶CCN活性和吸湿性均较高，其中平均吸湿性参数（k）为0.31.通过污染天和清洁天CCN特征的对比发现，污染天气溶胶和CCN数浓度均较高，但CCN活性和气溶胶吸湿性却较差，可能是由于新鲜排放的黑炭或有机物的影响.对比6种参数化方法的闭合结果，发现利用截断粒径和临界干粒径这两种参数对CCN数浓度进行预报的结果最为理想.此外，探讨了不同时间分辨率的参数对闭合结果的影响，对比发现参数时间分辨率的提高只增加了闭合结果R²的值，对闭合斜率的影响基本可以忽略，因此综合考虑，本研究可直接利用各参数的整体日变化平均来进行CCN数浓度的闭合.

Characterization and prediction of cloud condensation nuclei activity in the northern suburb of Nanjing

The size-resolved CCN activation properties of aerosol particles with diameters of 8.2~346nm were measured using SMPS-CCNC with full scan mode from November to December 2016 in the northern suburb of Nanjing, and six parameterization methods were used to predict the number concentration of CCN. The results showed that both the CCN activity and hygroscopicity of aerosols in Nanjing were relatively high, with an average hygroscopicity parameter (κ) of 0.31. From comparison of the CCN properties in clean and polluted conditions, it was found that the polluted conditions were characterized by relatively high aerosol and CCN number concentrations, but lower CCN activation and aerosol hygroscopicity, which may be accounted for the freshly emitted black carbon or organics. By comparing the closure results of six parameterization methods, it was found that the prediction of CCN number concentration by using cut-off diameters and critical dry diameters generated best result. Furthermore, the effects of parameters with different time resolution on the closure results were discussed, and it was found that the improvement of the time resolution of parameters could only increase the R² value of the closure result, whereas the effects on closure slope could almost be ignored. Therefore, it was suggested that the average diurnal variation of each parameter can be directly used to predict the CCN number concentration.