Analysis on Comprehensive Observation of Artificial Precipitation Enhancement Operation for a Convective-Stratiform Mixed Cloud

Based on the designed cloud physical observation and cloud seeding experiment data in Zhangjiakou,Hebei Province on April 18,2009.the precipitation enhancement seeding condition and cloud precipitation development of convective-stratiform mixed clouds were studied combined with satellite,radar,radio sounding and precipitation observation,etc.The results show that the precipitation cloud system is convective-stratiform mixed clouds with large amount of super-cooled liquid water,which is very suitable to be seeded.During the seeding period,highly seeded region is the main part of operated clouds.There are some relationships between the cloud seeding ability and radar echo.The intensity of C-band radar echo is in good accordance with precipitation particle spectrum,but in weak relativity of cloud particle spectrum.After the seeding operation,the concentration of small-particle decreased,while large cloud droplet and raindrop concentration increase,and radar echo show a bright band in the relevant position.Through calculating the rainfall variation rate between seeding region and contrast region,a method of analyzing the seeding effect is proposed.The calculated result of this case shows that the rainfall increase about 3~4h after seeding operation,and rainfall amount increased by 120%~180%.