【摘要】 2017年5月22日河北省出现一次低槽冷锋降水过程,河北省人工影响天气办公室利用机载粒子测量系统在太行山东麓区域对积层混合云进行了5次垂直探测。依据这些飞机探测资料结合石家庄天气雷达和邢台皇寺观测站的Ka波段云雷达资料分析了积层混合云的微物理结构和增雨作业条件。结果表明,降水云系出现在低槽槽前西南气流中,积层混合云由冷、暖云组成,云厚大于5 km,暖云厚度大于2 km,冷云厚度大于3 km,0℃层高度位于3577～4004 m,云底温度为15. 4℃,云顶温度为-17℃。云内出现最强雷达回波达45 d BZ的对流雨核,人工增雨作业应在雷达回波强度不超过40d BZ,且4000 m以上雷达回波强度不超过30 d BZ积层混合云区实施增雨作业。嵌入对流核的积层混合云中,5000 m以上冷云中上层过冷水含量达0. 2 g·m-3,比稳定的层状云中过冷水含量提高2～4倍;丰富的过冷水从雨核发展初期维持到雨核发展盛期,且该高度层是冰晶重要增长区,温度在-15～-5℃之间,适合催化作业。更多还原

【Abstract】 A cold front precipitation process caused by low trough occurred in Hebei province on May 22,2017.The Hebei weather modification office used an airborne particle measurement system to carry out five vertical soundings for the stratiform clouds with embedded convections developed in the eastern Taihang mountain. In this paper,the microphysical structure of stratiform clouds with embedded convections and the conditions for cloud seeding were both analyzed based on the data from aircraft observations,The meteorological radar in Shijiazhuang and the Kaband cloud radar at Huangsi,Xingtai. The precipitation clouds were found in the southwesterly air current before the low trough as the stratiform clouds with embedded convections were composed of both cold and warm clouds.Our results showed that the clouds were thicker than 5 km and the thicknesses of warm and cold clouds were greater than 2 km and 3 km respectively. The height of 0 ℃ layer was located at 3577 ～ 4004 m,while the temperature at the bottom and top of the clouds were 15. 4 ℃ and-17 ℃ respectively. A 45 d BZ radar reflectivity was detected indicating as the strongest echo of convection bubble within the clouds. However,to carry out cloud seeding,the strongest radar echo should be less than 40 dBZ and in the seeding area of convective stratiform clouds above 4000 m the radar echo should be less than 30 dBZ. The supercooled water was found in the upper-middle layers of the cold cloud above 5000 m with a content of 0. 2 g·m-3. This supercooled water content would be 2 ～ 4 times richer than that of stable stratiform clouds would contain. Besides,abundant supercooled water was observed along the initial and development stage of convective bubbles. Since this layer was the key area for ice crystal growth and the temperature varied from-15 ℃ to-5 ℃,this cloud was suitable for seeding.更多还原