Numerical Simulation Study On Microphysical Structure And Cloud Seeding In Summer Cloud System Of The Qilian Mountain Region

Based on the dynamic frame of GRAPES model, a new tow-moment microphysical scheme is developed and incorporated in the model. Two summer mountainous area clouds and precipitation processes are simulated in Qilian Mountain region by using the model which contains the new cloud physics scheme. The microstructure of mountainous area cloud is analyzed and compared with several kinds of data, including FY-2 satellite cloud photograph, synoptic map, surface precipitation data and radar data.As a whole, the model including new tow-moment microphysical scheme is able to reveal the distribution of precipitation and intensity prediction. The evaluation of the cloud which simulated by the model is basically consistent with the satellite cloud photograph and radar data. Simulate results show that the new tow-moment scheme has great capability to study microphysics structure of cloud system.In summer, the clouds in the west of the Qilian Mountain region are stratus, mostly due to forced up lift of landform when southwest air stream cross the mountain. The clouds in the east of the Qilian Mountain region are cumulus, mostly due to the horizontal wind shear by the influence of west Pacific Subtropical High. The cloud system of the Qilian Mountain region is constituted by those two different kinds of cloud.In the stratus, cloud ice, cloud water, snow, graupel and rain water can in divide into three layers, the cloud ice and cloud water locate high layer, the snow and graupel locate middle layer ,and the rain water locate low layer. In the cumulus, the distribution of cloud water is wider, other microphysics variables are mixed together. Base on the study, a conceptual model of cloud system of the Qilian Mountain region is given.In this paper, different seeding methods are designed to make seeding simulation, in order to study the influence of precipitation processes and the macro and micro structures of cumulus by seeding at the different stages and different places.After seeding simulation, the main analysis results are as follows: The artificial ice crystals seeding in the initial stage of cumulus can lead to wider distribution of rain enhancement than seeding in the development stage. The center region of rain enhancement locate downwind direction of seeding region, and few rain reduce region is found. The center region of rain enhancement in the seeding region, and at the upwind direction there has rain reduce region. The most efficiency of rain enhancement is 10﹪when seeding in 500hPa layer ,and 5﹪in 400hPa layer. Mostly due to the 500 hPa layer is near 0℃layer, the increased graupel crystals can melt more quickly , enhance the efficiency of precipitation and make effects of rain enhancement much better.