Intracloud (IC) lightning has been characterized using electric field waveforms and the temporal evolution of the flash, which are used to define an active stage. Of- ten, IC lightning will be characterized based on pulses in the electric field waveform due to the radiation portion of the electric field. These pulse characterizations have focused on pulse amplitude and frequency during the active stage in IC lightning, occurring early in the lightning flash. Further, little or no optical emission is associated, in previous studies, with the early portion of IC lightning; however, the early stage is typically identified as the most active portion of the IC waveform. With the objective of expanding how the active stage is characterized using optical emission and a spatio-temporal analysis of electric field waveforms with a focus on radiation field pulses, this study addresses IC lightning leader processes in a comprehensive fusion of electric field data and satellite based optical emission. Using the Huntsville Alabama Marx Meter Array (HAMMA), the North Alabama Lightning Mapping Array (NALMA) and the Lightning Imaging Sensor (LIS) this study consists of a spatio-temporal analysis of radiation field pulses from 19 IC flashes. Each flash is analyzed from initiation to bi-level breakdown and optical emission is present during the leader process of each flash. While the most common IC pulses are small amplitude and narrow (initial half cycle (IHC) width), pulses temporally matched with optical emission are often large amplitude (>1.0 V/m) and have large pulse widths (>20 microseconds). Additionally, the active stage is specfically associated with a period of vertical leader propagation, corresponding to the IC leader extending between two idealized charge layers in a thunderstorm. Features unique to this vertical extent include an increase in VLF source frequency and optical emission is first detected by LIS.
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机译：使用电场波形和闪光灯的时间演变来表征云内（IC）闪电，这用于定义活动阶段。由于电场的辐射部分，将基于电场波形中的脉冲来表征IC闪电十次。这些脉冲表征集中在IC闪电活动阶段的脉冲幅度和频率上，发生在闪电的早期。此外，在以前的研究中，很少或没有光发射与IC闪电的早期部分有关。但是，通常将早期确定为IC波形中最活跃的部分。为了扩展利用光发射和对电场波形的时空分析（以辐射场脉冲为重点）来表征有源级的特性，本研究针对电场数据和基于卫星的综合融合中的IC闪电领导工艺光发射。使用阿拉巴马州的汉斯维尔马克思仪表阵列（HAMMA），北阿拉巴马州的闪电测绘阵列（NALMA）和闪电成像传感器（LIS），这项研究包括对来自19个IC闪光灯的辐射场脉冲进行时空分析。从启动到二级击穿分析每个闪光灯，并且在每个闪光灯的前导过程中存在光发射。虽然最常见的IC脉冲幅度小且较窄（初始半周期（IHC）宽度），但与光发射在时间上匹配的脉冲通常幅度较大（> 1.0 V / m），并且脉冲宽度较大（> 20微秒）。另外，活动阶段与垂直引导传播的周期特别相关，对应于雷暴中两个理想电荷层之间延伸的IC引导。此垂直范围的独特功能包括VLF源频率的增加，并且首先由LIS检测到光发射。
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