云南中尺度对流系统地闪分布差异及成因  

DIFFERENCE IN DISTRIBUTION OF CLOUD-TO-GROUND LIGHTNING FOR MESOSCALE CONVECTIVE SYSTEMS IN YUNNAN AND ITS CAUSES

作　　者：张杰 张腾飞[2] 尹丽云[2] 谢屹然[2] 

机构地区：[1]云南省气象信息中心,云南昆明650034 [2]云南省气象台,云南昆明650034

出　　处：《热带气象学报》2014年第6期1146-1158,共13页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目(41265001;41305002);云南省科技计划项目(2009CA014)共同资助

摘　　要：利用NCEP/NCAR资料以及气象卫星和闪电定位系统等探测资料对2010年3种中尺度对流雷暴系统进行分析。结果表明：MCS频繁地闪对应着TBB≤-52℃,但其低中心及其梯度大值区和地闪频数空间分布不同,MCS具有后侧对流发展型、中间对流发展型、前侧对流发展型等三种特征;北方低槽切变配合南方倒槽、高层偏北气流叠加在低层偏南气流上的垂直风场结构、深厚的减弱台风低压倒槽为MCS提供有利环流背景,而近地面800 h Pa中尺度辐合线是诱发MCS的直接影响系统,且对流和地闪易于在偏南暖湿气流或风辐合一侧发展;500 h Pa以下水平风辐合及高低层间垂直风切变和垂直风辐合导致强烈上升运动,低层上升气流和高层下沉气流的有利配合及稳定次级垂直环流保障上升气流的维持,为MCS发展提供抬升动力机制;高层强大偏东风和垂直风切变导致对流区在MCS后侧,高层偏东风速小于承载层导致对流区出现在MCS前侧,而弱的风或弱的垂直风切变则导致地闪发生在MCS中部对流区;低层大气温度高于周围大气和650~750 h Pa高湿层的存在为MCS发展提供足够热力不稳定条件和充沛水汽条件。With NCEP/NCAP and monitoring data from meteorological satellites and lightning detection systems, 3 types of mesoscale convective thunderstorm systems in 2010 are analyzed. The results showed that frequent cloud-to-ground （CG） lightning activity is corresponding to TBB≤-52℃, but its low-value center and the large-gradient area are different from the spatial distribution of CG lightning frequency. MCS has 3 types of convective development at the rear, middle and frontal portion. A northern low-trough shear allocated with a southern inverted trough, a vertical wind configuration in which an upper-level northerly current superimposed on a low-level southerly current and a deep, inverted low-pressure trough of a weakening typhoon are all advantageous circulation background for MCS. The mesoscale convergence line of 800 hPa near the surface is a system directly influencing the MCS. Convection and CG lightning tend to develop on the side of the southerly warm and wet current. Horizontal wind convergence bellow 500 hPa, vertical wind shear and convergence lead to strong ascending motion, and the advantageous allocation of ascending current on the low level and descending current on the high level and the existence of a steady secondary vertical circulation maintain the ascending current, supplying lifting dynamical mechanism for MCS development. Strong easterly wind and vertical wind shear on the high level cause the convective zone to be on the rear of MCS, convective zone is in the front of MCS when the high-level easterly wind speed is smaller than on 500 hPa, but a weak easterly wind and vertical wind shear make the CG lightning appear in the middle convective zone of MCS. It supplies sufficient conditions of thermal instability and plentiful water vapor so that the low-level atmosphere temperature is higher than the ambient temperature and there is a highly-wet layer on the 650 - 750 hPa layer.

关 键 词：天气学 中尺度对流系统 诊断分析 地闪分布差异 成因 气象卫星 

分 类 号：P445[天文地球—大气科学及气象学]