On phenomenology of compact intracloud lightning discharges

摘要: [1] We examined wideband electric fields, and magnetic field derivatives, narrowband VHF (36 MHz) radiation bursts produced by 157 compact intracloud discharges (CIDs). These poorly understood lightning events appear to be the strongest natural producers of HF-VHF radiation. All transported negative charge upward (or lowered positive charge), 150 were located U.S. National Lightning Detection Network (NLDN), 149 them correctly identified as cloud discharges. NLDN-reported distances from measurement station 5–132 km. Three types waveforms observed. About 73% CIDs occurred in isolation; 24% prior to, during, or following cloud-to-ground “normal” lightning; 4% pairs, separated less than 200 ms (“multiple” CIDs). For a subset 48 CIDs, geometric mean source height was estimated 16 It appears that some actually above tops clear air convective surges (plumes) overshooting tropopause penetrating deep into stratosphere. same peak normalized 100 km (inclined distance) high 20 V/m, for 22 within 10–30 (horizontal distance), it 15 both which are higher first strokes lightning. The means total pulse duration, width initial half cycle, ratio opposite polarity overshoot 23 μs, 5.6 5.7, respectively.