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

R. A. Marshall, T. Adachi, R. R. Hsu, A. B. Chen

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


We examine narrowband VLF observations and investigate the association of early VLF perturbations with gigantic jets recorded by the Imager of Sprites and Upper Atmospheric Lightnings (ISUAL) instrument aboard FORMOSAT-2. From its inception in 2004 to April 2013, the ISUAL instrument has recorded 90 gigantic jets using a triggered camera. Stanford VLF receivers located around the world are used to detect perturbations to VLF transmitter signals associated with lightning. While nine gigantic jet events occurred within 100 km of a VLF transmitter-receiver great circle path, only four early VLF events were detected in association with three ISUAL gigantic jets. One of these is a moderate event of 0.4 dB amplitude change, and the others are very small. The recovery time of these events are less than a couple of minutes and so do not constitute the "long recovery" early VLF events that have been postulated to be associated with gigantic jets. We speculate on possible explanations for the lack of other events on monitored paths, including a lack of significant ionization produced in the D region ionosphere by the gigantic jet event, weak transmitter signals recorded by the receivers, or mode effects on transmitter paths. Key Points Subionospheric VLF signals are analyzed at the times of ISUAL Gigantic Jets We find 4 early VLF perturbations at times of Gigantic Jets Gigantic Jets may not produce significant ionization as previously thought

Original languageEnglish
Pages (from-to)36-43
Number of pages8
JournalRadio Science
Issue number1
Publication statusPublished - 2014 Jan

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Earth and Planetary Sciences(all)
  • Electrical and Electronic Engineering


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