Characteristics of Thunderstorms That Produce Terrestrial Gamma Ray Flashes

Chronis, Themis; Briggs, M. S.; Priftis, George; Connaughton, V.; Brundell, James B.; Holzworth, R. H.; Heckman, S.; McBreen, S.; Fitzpatrick, G.; Stanbro, M.

doi:10.1175/bams-d-14-00239.1

Cited by 43 publications

(72 citation statements)

References 65 publications

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“…In some other cases, no sounding data were available. The estimated cloud top heights provided in this study were all found to be ≥9.5 km, similar to values reported previously in Chronis et al []. Some of the cloud top heights are suggestive of some TGFs being produced from overshooting cloud tops, with altitudes of ≥17 km.…”

Section: Resultssupporting

confidence: 89%

“…This might be expected as the IC+ association must have a peak current comparable or greater than CG lightning in order to be detected by the WWLLN. The finding that even such weak storms are capable of producing TGFs is in keeping with the conclusions drawn from Chronis et al [], although further investigation into such storms is required.…”

Section: Resultsmentioning

confidence: 99%

“…TGF energy spectra were also found to be consistent with production occurring at a source altitude of ∼15 km [ Dwyer and Smith , ]. Other studies of the gamma ray attenuation [ Williams et al , ; Fitzpatrick et al , ], spectral shape [ Carlson et al , ; Østgaard et al , ; Gjesteland et al , ], and meteorology [ Chronis et al , ; Gjesteland et al , ; Fabró et al , ] have also confirmed that TGFs are produced from thunderstorms with a wide range of convective strengths [ Chronis et al , ], but predominately at an altitude between 10 and 16 km. The study by [ Chronis et al , ] also reported a TGF (oTGF130606592) which originated from the rainband of tropical storm Andrea, which is also reported in this study.…”

Section: Introductionmentioning

confidence: 99%

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Terrestrial gamma ray flashes due to particle acceleration in tropical storm systems

et al. 2017

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Terrestrial gamma ray flashes (TGFs) are submillisecond flashes of energetic radiation that are believed to emanate from intracloud lightning inside thunderstorms. This emission can be detected hundreds of kilometers from the source by space‐based observatories such as the Fermi Gamma‐ray Space Telescope (Fermi). The location of the TGF‐producing storms can be determined using very low frequency (VLF) radio measurements made simultaneously with the Fermi detection, allowing additional insight into the mechanisms which produce these phenomena. In this paper, we report 37 TGFs originating from tropical storm systems for the first time. Previous studies to gain insight into how tropical cyclones formed and how destructive they can be include the investigation of lightning flash rates and their dependence on storm evolution. We find TGFs to emanate from a broad range of distances from the storm centers. In hurricanes and severe tropical cyclones, the TGFs are observed to occur predominately from the outer rainbands. A majority of our sample also show TGFs occurring during the strengthening phase of the encompassing storm system. These results verify that TGF production closely follows when and where lightning predominately occurs in cyclones. The intrinsic characteristics of these TGFs were not found to differ from other TGFs reported in larger samples. We also find that some TGF‐producing storm cells in tropical storm systems far removed from land have a low number of WWLLN sferics. Although not unique to tropical cyclones, this TGF/sferic ratio may imply a high efficiency for the lightning in these storms to generate TGFs.

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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Terrestrial gamma ray flashes due to particle acceleration in tropical storm systems

et al. 2017

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“…Meteorological images acquired by geostationary satellites (Meteosat‐10, Himawari‐7, and GOES 13/15) included in the AGILE meteoretrieving pipeline show the presence of convective systems in the region of interest, frequently lasting several hours in order to produce more TGFs detected at successive passages. These data show that the underlying thunderstorms producing multiple TGFs exhibit very different extensions and structures, quite consistent with the results found by Splitt et al [] and Chronis et al [], suggesting that there are no privileged types of thunderstorm for TGF production.…”

Section: Discussionsupporting

confidence: 91%

Detection of multiple terrestrial gamma‐ray flashes from thunderstorm systems

et al. 2016

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Since their discovery, Terrestrial Gamma ray Flashes (TGFs) exhibited an evident correlation with thunderstorms and lightning activity. The fleeting nature of these events and the heavy absorption of gamma rays in the lowest atmospheric layers severely hamper the observation of this phenomenon, making us reveal just a small fraction of a probably much wider population. As each thunderstorm produces a large amount of lightning discharges during its lifetime, it is reasonable that even a large amount of TGFs are produced during the same event. However, detection of multiple TGFs coming from the same storm is difficult to perform, as it requires the constant monitoring of a spatially limited geographic region: this is not an easy task to perform for satellites on high‐inclination orbits that make them experience nonnegligible latitudinal shifts at each orbital passage over a certain region, preventing the monitoring of a limited geographic region throughout successive overpasses. In this perspective, the quasi‐equatorial (2.5°) orbit of the Astrorivelatore Gamma ad Immagini LEggero (AGILE) satellite ensures a minimal latitudinal shift when flying over the same region at successive passages, allowing for the follow‐up of thunderstorms in time. We exploit this feature of the AGILE satellite to search for multiple TGFs coming from the same geographic region and, in particular, from the same thunderstorm. We carry out this search on the AGILE TGF database (2009–2016), ending up with a sample of 79 systems producing more than one TGF, both during the same overpass and up to four overpasses after. Data acquired by geostationary meteorological satellites and cross correlation with radio sferics detected by World Wide Lightning Location Network are used to support this investigation. The AGILE satellite for the first time clearly establishes the multiple occurrences of TGFs from convective thunderstorms, both on timescales of minutes to several hours.

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“…For one of the TGFs in the sample, we can verify our results by comparing the estimated altitude for the preferred model with an altitude that is determined independently using radar measurements [ Chronis et al , ]. For TGF130930128, we find that the estimated cloud top height is in agreement with the source altitude measurements from the spectral analysis.…”

Section: Discussionsupporting

confidence: 69%

The spectroscopy of individual terrestrial gamma‐ray flashes: Constraining the source properties

et al. 2016

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We report on the spectral analysis of individual terrestrial gamma‐ray flashes (TGFs) observed with the Fermi Gamma‐ray Burst Monitor (GBM). The large GBM TGF sample provides 46 events suitable for individual spectral analysis: sufficiently bright, localized by ground‐based radio, and with the gamma rays reaching a detector unobstructed. These TGFs exhibit diverse spectral characteristics that are hidden when using summed analysis methods. We account for the low counts in individual TGFs by using Poisson likelihood, and we also consider instrumental effects. The data are fit with models obtained from Monte Carlo simulations of the large‐scale Relativistic Runaway Electron Avalanche (RREA) model, including propagation through the atmosphere. Source altitudes ranging from 11.6 to 20.2 km are simulated. Two beaming geometries were considered: In one, the photons retain the intrinsic distribution from scattering (narrow), and in the other, the photons are smeared into a wider beam (wide). Several TGFs are well fit only by narrow‐beam models, while others favor wide‐beam models. Large‐scale RREA models can accommodate both narrow and wide beams, with narrow beams suggest large‐scale RREA in organized electric fields while wide beams may imply converging or diverging electric fields. Wide beams are also consistent with acceleration in the electric fields of lightning leaders, but the TGFs that favor narrow‐beam models appear inconsistent with some lightning leader models.

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Characteristics of Thunderstorms That Produce Terrestrial Gamma Ray Flashes

Cited by 43 publications

References 65 publications

Terrestrial gamma ray flashes due to particle acceleration in tropical storm systems

Terrestrial gamma ray flashes due to particle acceleration in tropical storm systems

Detection of multiple terrestrial gamma‐ray flashes from thunderstorm systems

The spectroscopy of individual terrestrial gamma‐ray flashes: Constraining the source properties

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