Publications [#336181] of Steven A. Cummer

Papers Published

1. Bowers, GS; Smith, DM; Kelley, NA; Martinez-McKinney, GF; Cummer, SA; Dwyer, JR; Heckman, S; Holzworth, RH; Marks, F; Reasor, P; Gamache, J; Dunion, J; Richards, T; Rassoul, HK, A Terrestrial Gamma-Ray Flash inside the Eyewall of Hurricane Patricia, Journal of Geophysical Research: Atmospheres, vol. 123 no. 10 (May, 2018), pp. 4977-4987, American Geophysical Union (AGU) [doi]
   (last updated on 2023/06/01)

   Abstract:
   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.