石家庄地区雾霾天气下云滴和云凝结核的分布特征

2009年5~10月在石家庄地区对雾霾天气下的近地面到高空的云雾滴和云凝结核(CCN)进行了7架次飞机探测.利用PMS云粒子测量仪器、机载温湿仪和连续气流纵向热梯度云凝结核仪获得的云雾粒子和云凝结核(CCN)探测资料,分析了层积云(Sc)和高积云(Ac)中云粒子浓度、液态含水量、粒子算术平均直径和粒子有效平均直径的垂直分布特征;分析了CCN垂直和水平分布特征以及谱分布.结果表明雾霾天气状况下,云滴数浓度在102个/cm3量级上.高云粒子粒径总体大于低云粒子.云含水量平均值范围为0.03~0.14g/m3;地面到600 m高度内, CCN值的平均值为3034cm-3(过饱和度S=0.3%).对CCN的活化谱进行拟合表明石家庄属于典型大陆性核谱,云对CCN有消耗作用,逆温层的存在使得该区CCN浓度累积增加.

Distribution characteristics of cloud particles and cloud condensation nuclei during haze/fog events in Shijiazhuang

Cloud droplets and cloud condensation nuclei(CCN) over Shijiazhuang area,Northern China,were measured based on airborne instruments during May to October,2009.The data obtained from 7 flights were used to analyze the characteristics of number concentration,liquid water content,the mean diameter and the effective diameter of cloud droplets,as well as the spatial,temporal and spectral distribution of CCN in stratocumulus and altocumulus clouds under foggy/hazy weather conditions.The results show that the number concentration of cloud droplets was in the 102 orders of magnitude high under foggy/hazy weather conditions,and that the sizes of cloud particles measured at higher levels were larger than that at lower levels.The mean values of the cloud water content calculated from the droplet size spectra were between 0.03 to 0.14g/m3,and the mean value of CCN concentration averaged between the surface and at 600m high was 3034cm-3(for supersaturation of 0.3%).The size distribution of CCN was fitted with a power law function and was shown of continental type.The results also show that clouds had a scavenging effect on CCN,but the CCN concentration could be increased remarkably due to present of an inverse layer.