Numerical Simulation Study On Microphysical Structure And Cloud Seeding In Mixed Convective-stratiform Cloud

Mixed convective-stratiform cloud is composed of stratus and embeded cumulus. Mixed convective-stratiform cloud provides abundant cloud-water resources. So investigating their microphysical structure and seeding methods by numerical simulation is necessary. It is important for tackling the northerly China drought through reasonable exploiture of aerial water resources.In this paper, the ARPS mesoscale model is improved by modified its cloud microphysical. One case of stratocumulus is simulated in the northly China by the improved ARPS model, the microphysics structure and precipitation formation mechanism are investgated, comparing with observation datas. At one time, several seeding projects are tried, and then we analyzed the impact of seeding at different locations to cloud microphysics characteristics.As a whole, the model including new tow-moment microphysical scheme is able to reveal the distribution of precipitation and microphysics structure of cloud system. The evaluation of the cloud which simulated by the model is basically consistent with the satellite cloud photograph and radar data.Observation datas reveal this mixed convective-stratiform cloud precipitation has weak convection. Simulated distribution of precipitation and intensity prediction conform the observation, distribution is non-homogeneous. Simulated cloud echo on PPI reveal scattered non-regularly distributed convective cloud in a vast expanse of sheet stratus, the echo intensity of the convective cloud is about 40dbz.Cumulus embeded stratus vertical accumulated liquid water content is higher.In different phase of cloud development, vertical accumulated liquid water content has a significant change, at the same time, vertical accumulated liquid water content horizontal distribution is non-homogeneous.Cumulus embeded stratus has abundant cloud-water, strong ascending motion and driving precipitation. Stratus has faint ascending motion and infirm precipitation.Isolated Cumulus lives shortly, Cumulus embeded stratus can live long. Hydrometeor at different location has significant distribution and content change. Cumulus embeded stratus has more cloud-water and graupel content, stratus ha little cloud-water and graupel content.In mixed convective-stratiform cloud, ice mainly increase by deposition .snow increase by deposition, impacting ice and collection cloud. Graupel mainly come from snow.melting of graupel is main source of rain.After seeding simulation, the main analysis results are as follows: The artificial ice crystals seeding in cumulus can lead to wider distribution of rain enhancement than seeding in stratus,rain enhancement is greater, continuance time is longer, area of change is wider. Suitable seeding dose is ten times of natural ice concentration; ennough thick seeding temperature layer is integrant.