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

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.