Analysis on Microphysical Characteristics and Seedability of a Stratiform Cloud in Spring over North China

Based on the airborne observation data obtained by the Particle Measuring System( PMS) over the central region of Hebei on April 4,2013,the microphysical characteristics and artificial precipitation conditions of the stratus cloud were analyzed by combining with Micaps,satellite and additional precipitation observation,etc. The results show that the seeding cloud was a typical precipitation stratus. The average number concentration of small cloud droplet was 147 cm-3in the seeding cloud,and the maximum concentration was 737 cm-3,the mean diameter of cloud droplet was 4. 29 μm. The mean value and the maximum value of super cooled liquid water content in cloud was 0. 03 g / m3 and 0. 51 g / m3,respectively. The maximum number concentrition of ice crystals was 1. 12 × 10-3个/( cm3·μm) in the distribution of cloud droplet spectrums and it was quite suitable to be seeded. The seeding effect was significant by calculating the rainfall variation rate in the seeding zone and the contrast zones. The quantitative calculations show that the rainfall significantly increased in 3-4 hours after seeding operation and the rainfall amount in the seeding region was 1 to 3 times more than that in the contrast region. Comprehensive analysis confirmed the effectiveness of the seeding operation. The radar reflectivity was more related to surface rainfall than TBB.