Abstract:Artificial cloud seeding was carried out by Weather Modification Office of Hebei Province on clouds in a reflux and westerly synoptic system over central and southern region of Hebei on 19 April 2013. The cloud seeding and detection site was located in the updraft airflow in front of the trough and in the reflux. The characteristics of the precipitation are: (1) the precipitation structure is characterized by pre trough cloud and reflux cloud, where large particles grew mainly in the upper front of trough; (2) both the temperatures of pre trough cloud and the according cloud top were higher while the reflux cloud was colder, causing the solid precipitation particles to block together and resulting in the enhancement of surface snow; (3) the number concentration of big cloud particles and precipitation cloud particles was high. Moreover, there were abundant small cloud particles. The value of the intercept of the full spectrum fitting curve exceeded 2 (b>2), suggesting it is suitable for seeding operation. In addition, application of airborne measured microphysical parameters, satellite, radar and air sounding data in refined operations were analyzed. The results suggest that variations in micro structure, satellite and radar parameters within cloud are significant after the operation work. The regional variation of surface precipitation has passed the analysis on significance, but whether the difference before and after the affected area is the catalytic effect needs further verification.