A Terrestrial Gamma-Ray Flash inside the Eyewall of Hurricane Patricia

G. S. Bowers, D. M. Smith, N. A. Kelley, G. F. Martinez-McKinney, S. A. Cummer, J. R. Dwyer, S. Heckman, R. H. Holzworth, F. Marks, P. Reasor, J. Gamache, J. Dunion, T. Richards, H. K. Rassoul

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


On 23 October 2015 at ~1732 UTC, the Airborne Detector for Energetic Lightning Emissions (ADELE) flew through the eyewall of Hurricane Patricia aboard National Oceanic and Atmospheric Administration's Hurricane Hunter WP-3D Orion, observing the first terrestrial gamma-ray flash (TGF) ever seen in that context, and the first ever viewed from behind the forward direction of the main TGF gamma-ray burst. ADELE measured 184 counts of ionizing radiation within 150 μs, coincident with the detection of a nearby lightning flash. Lightning characteristics inferred from the associated radio signal and comparison of the gamma-ray energy spectrum to simulations suggests that this is the first observation of a reverse beam of positrons predicted by the leading TGF production model, relativistic runaway electron avalanches. This paper presents the first experimental evidence of a previously predicted second component of gamma-ray emission from TGFs. The brightest emission, commonly observed from orbit, is from the relativistic runaway electron avalanche bremsstrahlung; the second, fainter component reported here is from the bremsstrahlung of positrons propagating in the reverse direction. This reverse gamma-ray beam penetrates to low enough altitudes to allow ground-based detection of typical upward TGFs from mountain observatories.

Original languageEnglish (US)
Pages (from-to)4977-4987
Number of pages11
JournalJournal of Geophysical Research: Atmospheres
Issue number10
StatePublished - May 27 2018


  • eyewall
  • Hurricane Patricia
  • lightning
  • positrons
  • terrestrial gamma-ray flash
  • TGF

ASJC Scopus subject areas

  • Atmospheric Science
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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