The rarity of terrestrial gamma-ray flashes

Smith, David M.; Dwyer, J. R.; Hazelton, B. J.; Grefenstette, Brian W.; Martinez-McKinney, G. F.; Zhang, Z. Y.; Lowell, A.; Kelley, N. A.; Splitt, M. E.; Lazarus, S. M.; Ulrich, W.; Schaal, M.; Saleh, Z.; Cramer, E. S.; Rassoul, H. K.; Cummer, Steven A.; Lu, Gaopeng; Blakeslee, Richard J.

doi:10.1029/2011gl046875

Cited by 46 publications

(70 citation statements)

References 30 publications

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“…The frequency of glows that ADELE observed at cruise altitude-despite not passing directly through as on 21 August-demonstrates that the glow discharge process is not rare or anomalous, especially when compared with TGFs 40 . All of the other glows, except one, occurred when the Gulfstream V was passing near an active lightning cell.…”

Section: Discussionmentioning

confidence: 88%

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

et al. 2015

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Gamma-ray 'glows' are long duration (seconds to tens of minutes) X-ray and gamma-ray emission coming from thunderclouds. Measurements suggest the presence of relativistic runaway electron avalanches (RREA), the same process underlying terrestrial gamma-ray flashes. Here we demonstrate that glows are relatively a common phenomena near the tops of thunderstorms, when compared with events such as terrestrial gamma-ray flashes. Examining the strongest glow measured by the airborne detector for energetic emissions, we show that this glow is measured near the end of a downward RREA, consistent with occurring between the upper positive charge layer and the negative screening layer above it. The glow discharges the upper positive layer by Z9.6 mA, strong enough to be an important charging mechanism of the storm. For this glow, the gamma-ray flux observed is close to the value at which relativistic feedback processes become important, with an avalanche multiplication factor of 4,500.

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Section: Discussionmentioning

confidence: 88%

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

et al. 2015

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“…However, the flux of these gamma rays is generally many orders of magnitude lower than TGFs. Two events that did have TGF‐like fluxes were a ground‐based observation of a TGF‐like burst seen at sea level in Florida [ Dwyer et al , 2004a] and an observation of a TGF by the ADELE instrument onboard an NCAR‐NSF Gulfstream‐V aircraft [ Smith et al , 2011]. Both of these events appeared to be very similar to the TGFs observed from space.…”

Section: Introductionmentioning

confidence: 94%

“…Currently, most TGFs are believed to be produced inside thunderclouds during the initial stage of upward positive intracloud (IC) lightning [ Stanley et al , 2006; Lu et al , 2010; Shao et al , 2010; Connaughton et al , 2010; Lu et al , 2011]. However, how the lightning is related to the TGF production has not been clear, nor has it been well understood why some lightning produces TGFs while many others do not [ Splitt et al , 2010; Smith et al , 2011].…”

Section: Introductionmentioning

confidence: 99%

The relativistic feedback discharge model of terrestrial gamma ray flashes

2012

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.[1] As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two-and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.

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“…Is the TGF-generating process common and just the source altitude (Williams et al 2006; dictates whether the TGF is detectable at high altitudes? Recent work suggests not (Smith et al 2011b) but identifying a definitive signature of TGF-producing lightning flashes would give important insight into what is different about these flashes.…”

Section: The Tgf-lightning Connectionmentioning

confidence: 99%

“…The calculated luminosity of this event given the 10 km distance was comparable to that associated with TGFs seen from space (about 10 17 relativistic electrons needed). Perhaps more importantly, ADELE passed within 10 km of over 1000 other discharges detected by ground-based sferic networks without detecting any other TGF (Smith et al 2011b). The authors concluded that TGFs, even if there was a population too faint to be seen from orbit, are rare events, only associated with 0.1-1 % of lightning flashes.…”

Section: Adele Tgf Observationsmentioning

confidence: 99%

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

2012

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It is now well established that both thunderclouds and lightning routinely emit x-rays and gamma-rays. These emissions appear over wide timescales, ranging from submicrosecond bursts of x-rays associated with lightning leaders, to sub-millisecond bursts of gamma-rays seen in space called terrestrial gamma-ray flashes, to minute long glows from thunderclouds seen on the ground and in or near the cloud by aircraft and balloons. In particular, terrestrial gamma-ray flashes (TGFs), which are thought to be emitted by thunderclouds, are so bright that they sometimes saturate detectors on spacecraft hundreds of kilometers away. These TGFs also generate energetic secondary electrons and positrons that are detected by spacecraft in the inner magnetosphere. It is generally believed that these x-ray and gamma-ray emissions are generated, via bremsstrahlung, by energetic runaway electrons that are accelerated by electric fields in the atmosphere. In this paper, we review this newly emerging field of High-Energy Atmospheric Physics, including the production of runaway electrons, the production and propagation of energetic radiation, and the effects of both on atmospheric electrodynamics.

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The rarity of terrestrial gamma-ray flashes

Cited by 46 publications

References 30 publications

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

Relativistic electron avalanches as a thunderstorm discharge competing with lightning

The relativistic feedback discharge model of terrestrial gamma ray flashes

High-Energy Atmospheric Physics: Terrestrial Gamma-Ray Flashes and Related Phenomena

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