云南4次热带系统影响强对流风暴卫星云图和地闪特征

利用NCEP再分析气象资料及FY-2E卫星云图、地闪、地面自动站和气象灾情等资料对热带系统影响下的4类强对流风暴卫星云图特征和地闪演变规律进行分析。结果表明:西移北抬的赤道辐合带、副高、热带低压等热带系统外围偏东、西南和东北气流为强对流风暴发生发展提供有利环流背景及充足水汽和较高的对流有效位能,800 hPa中尺度辐合线及风随高度顺转和高层反气旋低层气旋的垂直流场结构为强对流风暴提供动力条件;在高能高湿环境条件下,由于辐合抬升作用,对流单体生成、不断长大、有规律排列、相互合并发展成不同大小和形状的单单体风暴、多单体风暴、飑线、MCC,结构密实和不均匀,伴随激烈地闪的同时产生冰雹大风和短时强降水等强对流天气;4种类型强对流风暴云顶亮温与总、负、正闪频数随时间演变规律基本一致,正、负地闪活跃程度能表征强对流风暴发展演变状况,与云顶亮温之间存在较好的相关关系,总(负)地闪频数演变趋势与云顶亮温演变趋势相反。

Satellite cloud picture and CG lightning characteristics of strong convective storms with four times of tropical systems influencing in Yunnan

By using NCEP reanalysis meteorological data, FY-2E satellite data, CG lightning data, automatic ground station data and meteorological disaster data, the satellite nephogram characteristics and the CG lightning evolution rules of four types of severe convective storms were analyzed under the influence of tropical systems. When tropical systems such as the equatorial convergence zone, the subtropical high and the tropical depression move to the west and the north, the easterly, southwestern and northeastern air currents around them provide favorable circulation background, sufficient water vapor and higher convective available potential energy for the development of severe convective storms, and the 800 hPa mesoscale convergence line and the vertical flow field contracture which the wind is clockwise with height and the anticyclone on the high level superimposes the cyclones on the low level provide dynamic conditions for severe convective storm. Under the condition of high energy and high humidity, due to the role of convergence and uplift, small convection cells generate, grow gradually, arrange regularly and merge with each other to develop into single storm, multi-cell storm, squall line and MCC of different sizes and shapes, whose structures are dense and uneven. They can not only produce furious CG lightning, but also produce hailstorm, gale and short-time heavy rainfall. The evolution of the cloud top temperature and the total, negative and positive lightning frequency with time are consistent for four types of strong convective storm, positive and negative CG lightning activity can characterize strong convective storm development and evolution, which has good correlation with cloud top temperature. Total (negative) CG lightning evolution is contrary to the trend of cloud top temperature evolution.