江淮地区一次雷暴过程双极性窄脉冲事件活动特征的相关研究

Analysis of the characteristics of narrow bipolar event in a thunderstorm process in Jianghuai region

利用2014年8月5日江淮地区一次产生多个双极性窄脉冲事件(narrow bipolar event,NBE)的雷暴个例,结合空基资料(TRMM卫星,NCEP/CPC Global IR Dataset)和地基资料(闪电探测和多普勒雷达回波数据),讨论了NBE与雷暴相关参数的关系以及位于不同雷暴区域NBE的孤立性和辐射强度.结果表明,NBE主要发生在云顶温度小于210 K、极化修正亮温(PCT-85)小于100 K的雷暴对流旺盛区域.通过分析NBE与30 dBZ多普勒雷达回波最大发展高度及闪电频次的关系,发现NBE主要发生于闪电频次较高时期,且NBE与闪电频次的相关性强于其与30 dBZ雷达回波最大高度的相关性.对NBE孤立性及VLF/LF波段辐射强度的分析表明,大多数孤立NBE发生于雷暴发展期,位于20 dBZ及以下的NBE辐射强度最大且最孤立.

The relationship between narrow bipolar events (NBEs) and thunderstorm parameters and the isolation and radiation intensity of NBEs in different regions of a thunderstorm on August 5th, 2014 in Jianghuai region was investigated based on the satellite-based NCEP/CPC Global IR data, TRMM PR/TIM data, and the ground-based radar and lightning detection data. The results show that NBEs mainly occurred in the convective areas of the thunderstorm with the cloud top temperature being less than 210 K and the polarization correction temperature(PCT-85) less than 100 K. By analyzing the correlation between NBEs and the maximum height of 30 dBZ radar echo and lightning frequency, the results also show that NBEs mainly occurred during the high frequency period of lightning, and that the correlation between NBEs and lightning frequency is stronger than that between NBEs and the maximum height of 30 dBZ radar echo. The investigation of NBE isolation and the pulse peak intensity of VLF/LF band indicates that most isolated NBEs occurred in the early stage of the thunderstorm, and that the NBE radiation intensity below 20 dBZ was the strongest and most isolated.