一次对地转移电荷极性两次反转的人工引发雷电特征及反转机制分析  

Characteristics and mechanism of a triggered lightning with two polarity reversals of charges transferred to ground

作　　者：唐国瑛 孙竹玲 蒋如斌[2] 李丰全 刘明远[2,3] 刘昆 郄秀书 Tang Guo-Ying;Sun Zhu-Ling;Jiang Ru-Bin;Li Feng-Quan;Liu Ming-Yuan;Liu Kun;Qie Xiu-Shu(College of Electronic Engineering(College of Meteorological Observation),Chengdu University of Information Technology,Chengdu 610225,China;Key Laboratory of Middle Atmosphere and Global Environment Observation,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]成都信息工程大学电子工程学院(大气探测学院),成都610225 [2]中国科学院大气物理研究所,中层大气和全球环境探测重点实验室,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049

出　　处：《物理学报》2020年第18期367-380,共14页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:41875008,41775012,41630425)资助的课题.

摘　　要：利用闪电甚高频干涉仪动态成像结果,并结合通道底部电流、电场和光学观测资料对一次罕见的、对地转移电荷极性反转两次的双极性人工引发雷电放电特征进行了详细研究,首次观测到直接导致极性反转的云内击穿放电过程,探讨了对地转移电荷极性两次反转的物理机理.结果发现,此次闪电无回击过程、初始连续电流阶段对地转移电荷极性经历了负-正-负的两次反转,转移电荷量分别约-40.0 C,+13.3 C和-1.0 C.负极性初始连续电流衰减过程中,一支击穿空气的负先导起始于已电离的正先导分支通道上并形成悬浮通道,水平发展28.816 ms后,接地主通道上发生负极性击穿连接到了悬浮通道末端正电荷聚集处或双向发展的悬浮通道的正极性端,随后对地转移电荷极性快速反转为正.负先导熄灭后,对地转移电荷极性缓慢反转为负.击穿空气的负先导连接到接地主通道和持续发展的正先导是此次双极性闪电对地转移电荷极性发生两次反转的重要原因.而负先导的起始,与正先导多分支同时发展引起的先导通道和环境电势分布差异密切相关.Characteristics of a triggered bipolar lightning flash obtained in the Shandong triggering lightning experiment(SHATLE)are analyzed based on simultaneous observation results of lightning very high frequency(VHF)interferometer map,channel-base current,fast electric field change and high-speed optical images.The flash lasts about 315 ms with only the initial continuous current(ICC).As the polarity of charges transferred to the ground varies from negative to positive and then to negative,the ICC can be mainly divided into three stages including the first negative ICC stage,positive ICC stage,and second negative ICC stage,respectively,for 152.755 ms,87.225 ms and 75.02 ms.Charges transferred to the ground during the three stages are about–40.0 C,+13.3 C and–1.0 C,respectively,with the peak current of about–3.8 kA,1.6 kA and–2.25 kA.According to the VHF interferometer map,during the first negative ICC stage,the upward positive leader(UPL)initiated from the top of the wire as negative charges starts to be transferred to the ground.The UPL develops at a two-dimensional(2D)speed of 3.7×10^4 m/s into the cloud and multiple positive branches develop in the form of small-scale and dense recoil leaders,keeping the increase of negative charge transferred to the ground.Then a negative leader(NL)initiates on a previously ionized positive branch channel and develops into the virgin air horizontally as a floating channel at a 2D propagation speed of 1.59×10^5 m/s.About 28.816 ms later after the NL develops,a negative pulse is detected in the fast electric field change,caused by a negative polarity breakdown discharge from the grounding trunk channel to the floating channel which is observed for the first time.Then about 39μs later,the first polarity of the channel-base current changes from negative to positive,and rapidly reaches a positive peak in 1.75 ms.Subsequently,with the positive ICC decreasing,the negative leader gradually terminates about 65.85 ms after the first polarity reversal,and then 21.38 ms later the c

关 键 词：先导 双极性闪电 人工引雷 甚高频辐射源定位 

分 类 号：P427.3[天文地球—大气科学及气象学]