干旱区云凝结核分布及其影响因子的观测研究

Observational study on the distribution of cloud condensation nuclei and its causes in drought region

利用DMTCCN仪对宁夏盐池、银川地区地面及高空的云凝结核(CCN)进行实时连续观测.大量资料分析结果表明,CCN日变化明显,受人为因素影响,清晨和傍晚出现高值.夜晚温度与CCN浓度呈正相关,白天相反;强降水对CCN具有一定冲刷作用;沙尘气溶胶没有有效增加盐池地区的CCN浓度.与华北地区比较,银川、盐池地区CCN浓度偏低.此外,研究表明,过饱和度越高,活化CCN浓度越大.根据N=CSK拟合活化谱,银川属于典型大陆性核谱.由于云内清除作用,高空CCN浓度下降明显,但逆温层的存在使得该区CCN浓度累积增加.

Using a droplet measurement technologies （DMT） cloud condensation nuclei （CCN） counter,distributions of CCN on the ground and in the air in Yanchi and Yinchuan of Ningxia Hui Autonomous Region were obtained.It was concluded that CCN had a distinctive diurnal cycle.The high concentration appears in the early morning and evening,affected by human activities.There was a positive correlation of CCN concentration with temperature during the day,and a negative correlation at the night.Heavy rainfall had a scavenging effect on CCN concentration,while dust aerosol did not increase CCN concentration effectively.With respect to other regions in North China,the CCN concentration in Yanchi was relatively low.With increasing supersaturation,more particles were activated.According to the expression N=CS k,the fitted spectra parameters in Yinchuan showed continental characteristic.In the air,CCN concentration decreased with height,especially in the cloud,which was due to scavenging while an inversion layer tended to increase CCN concentration.