Beijing Weather modification office
利用国内首台在线连续流量扩散云室，2017年冬季在华北地区高山站开展了大气冰核观测；结合常规气象要素、降水滴谱、气溶胶观测，分析了大气冰核数浓度特征，并对冰核活化参数化方法以及降雪对冰核的影响。结果表明：（1）大气冰核在不同时间的浓度差异较大，-20℃时数浓度变化范围为2.50～76.8 L-1，平均值为18.347 L-1；（2）大气冰核浓度随活化温度降低呈指数增加趋势，随过饱和度增加呈指数增加，凝华核化所占比例约为18.64%；（3）大气冰核与粒径大于0.5μm的气溶胶数浓度的关系可用参数化表示，相关性大于仅基于活化温度建立的参数化公式；（4）降雪过程大气冰核具有先增加后减少的特征。降雪开始后大气冰核数浓度增加，降雪后期系统过境伴随的大风，对气溶胶的清洗作用明显，大气冰核随之减少。本研究为在线连续流量扩散云室类型的冰核观测仪在国内首次使用，所建立的冰核参数化公式有助于华北地区冬季地形云及其降水的微物理特征研究，同时在云模式的发展和人工影响天气研究中也有重要的参考意义。
Ice nucleating particle (INP) concentrations are reported for a mountain site on the north-western margin of Beijing, during winter 2017, with the newly purchased continuous flow diffusion chamber(BJ-CFDC). Atmospheric INP concentrations characteristics are analyzed with weather elements, precipitation size distribution measurement and aerosol observation. The relationship among INP concentration, and activation temperature, super saturation with respect to water, aerosol with size larger than 0.5 m are developed. The result shows that atmospheric INP has a large variation at different activation temperature. It ranges between 2.50～76.8 L-1 at -20℃ with an average of 18.347 L-1. Atmospheric INP concentration increases exponentially both with lowering temperature and increasing super saturation respect to water. The result also shows atmospheric INP has a good correlation with the concentration of aerosol particles of sizes larger than 0.5 m. With this relation, the relevance of predicted and measured INP is higher than that the relationship built with only temperature. Atmospheric INP in snow days shows a characteristic of increasing firstly and decreasing later. INP concentration increase in the beginning of snow.The strong wind in the later period of snow scavenge the aerosols and lead to reduced concentration of INP. With the first continuous flow diffusion chamber type instrument used in China, the results of this paper will not only help to study the orographic cloud and precipitation in winter of north China, but also improve the support for development of cloud model and study in weather modification.