摘要
利用地面地闪定位资料、多普勒天气雷达和常规气象资料,分析了一次具有前部对流线和后部大范围层状云降水(LLTS)的典型中尺度对流系统(MCS)的闪电活动演变特征。整个MCS生命史中负地闪占主导地位,正地闪则表现不活跃。观测得到MCS消散阶段云闪与地闪的比例为2∶1,地闪主要分布在地面相对位温和对流不稳定能量均达到高值的区域;负地闪主要密集地分布在大于40dBZ的回波范围内;正地闪则稀疏地分布在30～40dBZ的回波范围内。在低于-40℃的温度区域内地闪分布较多,而密集的地闪分布在温度梯度大的区域内。结合单多普勒雷达的水平风场反演,发现地闪集中出现在气流表现为气旋性切变或水平风呈现切变的区域。该区域与MCS的强回波区相对应,并且地闪易发生在上升气流达到最大并开始出现下沉气流的阶段。
Based on the lightning location detection data, Doppler radar data, and synoptic information, this paper presents the lightning characteristics of a typical mesoscale convective system （MCS） in the north of Shandong Province on 1 August 2005. It is found that the negative cloud-to-ground （--CG） lightning is predominant over the positive cloud-to-ground （＋CG） lightning during the whole thunderstorm lifetime. At the dissipation stage, IC （intracloud lightning） /CG is 2： 1 within the detection range. And when the electric field changed greatly, the lightning happened frequently. The CG lightning mainly occurred in the regions with high values of convective available potential energy （CAPE） and surface equivalent potential temperature. The comparison between the location of lightning activity and radar echo shows that --CA3 usually clusters in the intense echo region with high reflectivity （〉40 dBZ）, while ＋CG usually disperse in the weak echo （30 dBZ - 40 dBZ） region. Relation between the cloud-top brightness temperature and the CG lightning location indicates that most flashes occurred in the area with temperature lower than -40℃, while the ＋CG lightning clustered in the region with the cloud-top temperature between -40℃ and -50℃. The comparison between the wind field retrieved from Doppler radar and the location of CG flashes indicates that the flashes are usually located in the cyclonic shear or wind shear areas which corresponds to the intense echo. The CG flashes are easier to happen in the stage that updraft reaches the maximum and downdraft appears.
出处
《大气科学》
CSCD
北大核心
2010年第1期95-104,共10页
Chinese Journal of Atmospheric Sciences
基金
中国科学院"百人计划"专项经费
国家自然科学基金资助项目40505001
40930949
关键词
地闪
水平风场
雷达回波
云顶亮温
中尺度对流系统
cloud-to-ground lightning, wind field, radar echo, mesoscale convective system, cloud-top brightness temperature
