Rare examples of early VLF events observed in association with ISUAL‐detected gigantic jets

摘要: [1] We examine narrowband VLF observations and investigate the association of early perturbations with gigantic jets recorded by Imager Sprites Upper Atmospheric Lightnings (ISUAL) instrument aboard FORMOSAT-2. From its inception in 2004 to April 2013, ISUAL has 90 using a triggered camera. Stanford receivers located around world are used detect transmitter signals associated lightning. While nine jet events occurred within 100 km transmitter-receiver great circle path, only four were detected three jets. One these is moderate event 0.4 dB amplitude change, others very small. The recovery time less than couple minutes so do not constitute “long recovery” that have been postulated be We speculate on possible explanations for lack other monitored paths, including significant ionization produced D region ionosphere event, weak receivers, or mode effects paths.