河北秋季层状云物理结构及适播性分析

Study on Physical Structure of Hebei Stratiform Clouds in Autumn and Its Seedability Condition

利用2006-2010年河北省人工影响天气办公室对29块云体9架次飞机探测(或作业)资料,统计分析了河北地区秋季层状云气溶胶粒子、云凝结核CCN、小云粒子、大云粒子、降水粒子浓度和云粒子有效直径等物理特征。结果表明,河北地区适宜增雨作业的云系为中、低或高、中、低搭配的层状云,过冷层催化有利于云体发展,促使气流流入形成正反馈。适宜催化的作业层指标有:云层高度为4582 m,云内平均含水量≥0.1 g·m-3,所对应温度为-8.0℃,小云粒子浓度为236.5 cm-3。

By using the data of the aircraft observations( or operations) in Weather M odification Office of Hebei Province from 2006 to 2010,statistical characteristics of 29 clouds from 9 flights collected mainly in stratiform clouds over Hebei area in autumn are presented,including number concentration of aerosol,CCN,small cloud particles,large cloud particles,precipitating particles and cloud particle effective diameter. It has been found that midde-low level or high midde-low level stratiform clouds are the appropriate clouds for precipitation modification over Hebei area,w hereby clouds obtain enhancement due to supercooled layer catalytic,contributing to the positive feedback of airflow. The case studies demonstrate that the supercooled layer indicators appropriate for seeding are operation altitude of 4582 m and liquid w ater content of no less than 0. 1 g ·m- 3,associated with temperature of- 8. 0℃ and small cloud particle concentration of 236. 5 cm- 3.