不同天气系统层状云微物理特征个例分析

摘要

利用PMS粒子测量系统和机载温湿仪观测获取的吉林省2007年5月15日高空槽和5月28日冷涡天气下降水云垂直探测资料，对比分析了两次不同天气系统下形成降水过程中云系的宏微观结构特征。结果发现，高空槽影响下的As 云中云滴数浓度最大值比冷涡影响的As-Sc云系高一倍；液态水含量方面，高空槽系统下As 云中在0℃附近取得最大值，冷涡系统下As-Sc云系中，最大值出现在上层As 云中-4．8℃左右处。高空槽系统影响下的As 云中，FSSP-100、2D-C和2D-P 探测到的粒子数浓度、含水量和平均直径随高度呈不均匀性分布；而冷涡影响的As-Sc云中，FSSP-100测得As 云中粒子平均直径远大于Sc，2D-C和2D-P探测到的上层As 云中粒子浓度和液态含水量分布相对均匀，而下层Sc 中粒子浓度、液态含水量值和平均直径都很小，这是由于云层之间存在干层，使As 云中的部分大云滴和雨滴在下降过程中迅速蒸发，不利于降水形成。不同高度层FSSP-100测得的粒子平均谱分布均差异较大。对云中可播性进行研究，结果发现高空槽影响的 As 云中可播区均为强可播区，冷涡系统影响的As-Sc云中可播区的1／2为强可播区。%Two cases of stratiform cloud precipitation in Jilin Province under the upper-level trough process on 15 May and the cold vortex on 28 May 2007 are analysed.The microphysical data are sampled with the airborne PMS probes and a hygrothermoscope.It is found that the vertical distribution of particle number concentration,liquid water content,mean diameter of FSSP-100,2D-C and 2D-P probes under upper-level trough on 15 May are not uniform and the maximum liquid water content is in 0℃ layer.In As-Sc under cold vortex on 28 May,the maximum particle number concentration of FSSP-100 in Sc and As are both 350 cm-3;the maximum LWC in As is one ordering more than in Sc and mean diameter in As is far more than in Sc.The particle number concentration and liquid water content of 2D-C and 2D-P in As are symmetri-cal,but teeny in Sc because of a dry layer between layers.The layer-averaged size distributions of small cloud particles in cloud of 2 cases are quite different.The seedability of cloud is studied.The result shows that the seedability of As clouds under upper-level trough is highly seedable clouds,the seedable clouds of As-Sc cloud system under cold vortex are 1/2 highly seedable clouds.