A terrestrial gamma-ray flash recorded at the Lightning Observatory in Gainesville, Florida

Tran, M. D.; Rakov, Vladimir A.; Mallick, S.; Dwyer, J. R.; Nag, A.; Heckman, S.

doi:10.1016/j.jastp.2015.10.010

Cited by 69 publications

(73 citation statements)

References 18 publications

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“…While astronomical satellites in near‐Earth orbits routinely detect TGFs beamed upward, on‐ground facilities have also detected similar phenomena but beamed downward, called downward TGFs. They have been observed with rocket‐triggered (Dwyer et al, ; Hare et al, ) and natural lightning discharges (Abbasi et al, , ; Colalillo, ; Dwyer et al, ; Tran et al, ). In particular, downward TGFs during winter thunderstorms are sometimes bright enough to produce a number of neutrons via photonuclear reactions (Babich, , ) close to the ground; thus, the neutrons and their byproducts can be observed by sea level measurements (Bowers et al, ; Enoto et al, ; Wada et al, , ).…”

Section: Introductionmentioning

confidence: 96%

High Peak‐Current Lightning Discharges Associated With Downward Terrestrial Gamma‐Ray Flashes

et al. 2020

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During 2017–2018 winter operation of the Gamma‐Ray Observation of Winter Thunderclouds experiment in Japan, two downward terrestrial gamma‐ray flashes (TGFs) that triggered atmospheric photonuclear reactions were detected. They took place during winter thunderstorms on 5 December 2017 and 9 January 2018 at Kanazawa, Ishikawa Prefecture, Japan. Each event coincided with an intracloud/intercloud discharge, which had a negative‐polarity peak current higher than 150 kA. Their radio waveforms in the low‐frequency band are categorized as a distinct lightning type called “energetic in‐cloud pulse” (EIP). Negative‐polarity EIPs have been previously suggested to be highly associated with downward TGFs, and the present observations provide evidence of the correlation between them for the first time. Furthermore, both of the downward TGFs followed “gamma‐ray glows,” minute‐lasting high‐energy emissions from thunderclouds. It is suggested that the negative EIPs took place with downward propagating negative leaders or upward positive ones developed in highly electrified regions responsible for the gamma‐ray glows.

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Section: Introductionmentioning

confidence: 96%

High Peak‐Current Lightning Discharges Associated With Downward Terrestrial Gamma‐Ray Flashes

et al. 2020

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“…They are one of the highest-energy natural photon emissions on Earth, but the mechanism for creating 10 17 to 10 18 high-energy electrons in the source region [Dwyer and Smith, 2005;Cummer et al, 2014] still remains unclear [Dwyer, 2012;Pasko, 2014]. At present, almost all of the thousands of reported TGFs have been detected by spaced-based gamma ray photon detectors [Fishman et al, 1994;Smith et al, 2005;Briggs et al, 2010;Marisaldi et al, 2010] (four TGF photon observations at ground level [Dwyer et al, 2004Tran et al, 2015;Hare et al, 2016] and one by aircraft have been reported). Ground-based gamma ray photon observations from TGFs are inherently challenging due to the strong atmospheric gamma ray attenuation from the low-altitude atmosphere, and the geometry-driven short horizontal detection range (a few kilometers on the ground), in contrast to a few hundred kilometers in low-altitude orbit.…”

Section: Introductionmentioning

confidence: 99%

Ground detection of terrestrial gamma ray flashes from distant radio signals

Lyu

Cummer

Briggs

et al. 2016

Geophysical Research Letters

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Terrestrial gamma ray flashes (TGFs) are brief bursts of energetic gammy‐ray photons generated during thunderstorms, which have been detected almost exclusively by satellite‐based instruments. Here we present three lines of evidence which includes the three out of three simultaneously observed pairs, the same occurrence contexts, and the consistent estimated occurrence rate, which indicate a direct relationship between a subset of TGFs and a class of energetic radio signal easily detectable by ground‐based sensors. This connection indicates that these gamma ray and radio emissions are two views of the same phenomenon and further enable detection of these TGFs from ground distant radio signals alone. Besides dramatically increasing the detection rate of TGFs, this ground detection approach can identify TGFs in continental and coastal areas that are at latitudes too high for present TGF‐detecting satellites and will provide more insights into the mechanism of TGF production.

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“…One TGF was associated with a 2003 classically triggered lightning flash [ Dwyer et al , ], and the other followed a return stroke in a natural cloud‐to‐ground flash in 2009 [ Dwyer et al , ]. A third ground‐level TGF was detected by the Lightning Observatory in Gainesville, FL, in 2015 [ Tran et al , ]. Here we report on a fourth TGF, one that was associated with an altitude‐triggered flash at the ICLRT on 15 August 2014.…”

Section: Introductionmentioning

confidence: 99%

Ground‐level observation of a terrestrial gamma ray flash initiated by a triggered lightning

et al. 2016

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We report on a terrestrial gamma ray flash (TGF) that occurred on 15 August 2014 coincident with an altitude‐triggered lightning at the International Center for Lightning Research and Testing (ICLRT) in North Central Florida. The TGF was observed by a ground‐level network of gamma ray, close electric field, distant magnetic field, Lightning Mapping Array (LMA), optical, and radar measurements. Simultaneous gamma ray and LMA data indicate that the upward positive leader of the triggered lightning flash induced relativistic runaway electron avalanches when the leader tip was at about 3.5 km altitude, resulting in the observed TGF. Channel luminosity and electric field data show that there was an initial continuous current (ICC) pulse in the lightning channel to ground during the time of the TGF. Modeling of the observed ICC pulse electric fields measured at close range (100–200 m) indicates that the ICC pulse current had both a slow and fast component (full widths at half maximum of 235 μs and 59 μs) and that the fast component was more or less coincident with the TGF, suggesting a physical association between the relativistic runaway electron avalanches and the ICC pulse observed at ground. Our ICC pulse model reproduces moderately well the measured close electric fields at the ICLRT as well as three independent magnetic field measurements made about 250 km away. Radar and LMA data suggest that there was negative charge near the region in which the TGF was initiated.

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A terrestrial gamma-ray flash recorded at the Lightning Observatory in Gainesville, Florida

Abstract: 2016-12-23T18:44:59

Cited by 69 publications

References 18 publications

High Peak‐Current Lightning Discharges Associated With Downward Terrestrial Gamma‐Ray Flashes

High Peak‐Current Lightning Discharges Associated With Downward Terrestrial Gamma‐Ray Flashes

Ground detection of terrestrial gamma ray flashes from distant radio signals

Ground‐level observation of a terrestrial gamma ray flash initiated by a triggered lightning

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