Leader process in 3D observed by VLF/LF broadband interferometer

We have been designing and developing a 3D lightning location system based on the broadband digital interferometry technique in VLF/LF band. The VLF/LF broadband digital interferometer (VLF/LF DITF) is able to locate lightning discharges such as return strokes, K events, and compact intracloud lightning discharges (CIDs), which are energetic breakdowns within thunderclouds several hundred kilometers away from the VLF/LF DITF. From July 2011 to now, a simultaneous observation of a VLF/LF band DITF and VHF broadband digital interferometers (VHF band DITF) were conducted in Kansai, Japan. We show the time series variation of an intracloud discharge initiated by a preliminary breakdown pulse train (PB), negative cloud to ground flash and intracloud discharge including K-event. VLF/LF DITF successfully located not only energetic breakdowns within thunderclouds but also leader processes.