一次夏季雷暴天气过程中闪电活动特征分析  

Analysis of lightning characteristics in a summer thunderstorm

作　　者：夏文梅[1] 徐芬[1] 慕熙昱[1] 付志康[2] 徐琪 

机构地区：[1]江苏省气象科学研究所,南京210008 [2]中国气象局武汉暴雨研究所,武汉430074 [3]民航江苏空中交通管理分局,南京210000

出　　处：《气象科学》2011年第5期652-658,共7页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(40665001;40475017;40775029;40975013);中国气象局新技术推广项目(CMATG2008M39)

摘　　要：利用探空资料、多普勒天气雷达和闪电定位仪数据,分析了2009年7月30日发生在南京地区一次雷暴天气过程的雷达及闪电数据时空演变特征。结果表明:对流有效位能Ecap比起K指数(IK)等对于对流潜势预报具有更明显的指示作用,0℃层和-10℃层高度的降低有利于雷暴云的雷电活动;整个过程以负闪为主导,闪电强度越大,闪电频数也越高,每次闪电峰值后,都对应一次谷值;闪电数据与多普勒天气雷达回波叠加后分析发现,回波的生消演变对应着闪电频数和强度的生消演变,负闪主要落在强回波中心区域,正闪零星分布于回波强度梯度较大的区域;雷达径向速度图像特征变化更能揭示闪电发生发展的机制,逆风区对应雷暴中心区域,不仅是强降水的中心区也是闪电的中心区,对逆风区的识别监测能够更好的指导雷暴预警报工作;利用雷达数据计算的云底动能施力参量,能够很好的描述支持闪电起电的热动力特征,云底动能施力对雷电增长的贡献有一段持续传输过程,该参量峰值比频闪峰值和强度峰值都约有0.5 h的提前量。Based on the sounding data,Doppler weather radar products and lightning data,the temporal and spatial evolution characteristics of the thunderstorm in the Nanjing region on July 30,2009 is presented.It is found that convective available potential energy Ecap is a better index in convection potential forecasting in comparison with IK index etc.The reduction of 0 ℃ and-10 ℃ temperature level is beneficial to the occurrence and development of the electrical activity in the thunderstorm.The negative lightning is predominant in comparison to positive lightning during the whole period.The increase of the lightning intensity corresponds to the higher flash rate.After each peak lightning,a lightning activity valley will appear.The comparison between location of lightning activity and radar echo shows that the development of the radar echo intensity corresponds to the evolution of flash rate and intensity.Negative lightning mainly clusters in the intensive echo region,while positive lightning usually scatters in the echo area with larger gradient.The characteristics of Doppler velocity PPI is better in order to reveal the mechanism of occurrence and development of lightning according to reflectivity PPI.AWR is the central area of heavy rain and lightning which also corresponds to the thunderstorm center region.It is helpful in the thunderstorm forecasting by the identification of AWR.It is feasible in describing the thermal characteristics and power characteristics of the lightning activity by Ekin index which is calculated by the radar data.The appearance of the Ekin peak value is ahead of the flash rate peak and the intensity peak value by about 30 minutes which has the forecast ability in lightning and is worth further studying.

关 键 词：闪电频数 零速度线 逆风区 

分 类 号：P458.3[天文地球—大气科学及气象学]