The horizontal profile of the atmospheric electric fields as measured during thunderstorms by the network of NaI spectrometers located on the slopes of Mt. Aragats

Chilingarian, A.; Hovsepyan, G.; Karapetyan, T.; Козлинер, Л. И.; Chilingaryan, S.; Pokhsraryan, D.; Sargsyan, B.

doi:10.1088/1748-0221/17/10/p10011

Cited by 8 publications

(3 citation statements)

References 12 publications

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“…Thus, although the pattern of the NSEF disturbances was rather different at both locations, the intracloud electric field was strong enough to unleash the runaway process and send numerous electrons and gamma rays in direction of the earth's surface. It was another proof (see for the first detection of the extended TGE flux in [7]), that during thunderstorms large areas below thunderclouds are radiated by the electron accelerator operated in the lower dipole. In Fig.…”

Section: Horizontal Profile Of the Atmospheric Electric Fieldmentioning

confidence: 94%

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Structure of thunderstorm ground enhancements

et al. 2020

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The comparative analysis of three thunderstorms on Aragats in May 2021 demonstrates that relativistic runaway electron avalanches (RREAs) are developing in large areas of the thunderous atmosphere. In the active storm zone, RREAs last tens of seconds to a few minutes, until lightning flashes terminate electron acceleration. If the lightning activity is far from the detector site, the measured enhancements of particle fluxes (thunderstorm ground enhancements -TGEs) smoothly decay when the atmospheric conditions cannot anymore sustain the electron runaway process. In this case, the TGE has a more or less symmetrical shape and can last up to 10 minutes and more. Thus, RREAs development is paired with lightning activity, creating huge electron fluxes preceding the development of lightning leaders. We show that the total surface area exposed to ionizing radiation can reach 100 km 2 and the total number of gamma rays directed to the earth's surface -can be estimated as ≈1.3*10 16 (for TGE particles with energies above 300 KeV). The differential energy spectra of electrons and gamma rays recovered from the data of particle spectrometers are used to estimate the height of a strong accelerating electric field region, which can extend down to tens meters above the earth's surface.

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Section: Horizontal Profile Of the Atmospheric Electric Fieldmentioning

confidence: 94%

“…Therefore, we recover only gamma ray energy spectrum with another spectrometer network operated on Mt. Aragats, namely, a network of large (12 x 12 x28 cm) NaI (TL) spectrometers with the energy threshold of 300 KeV (see details in [7]). As we can see in Fig.…”

Section: The Largest Tge Event On 22 September 2022mentioning

confidence: 99%

Structure of thunderstorm ground enhancements

et al. 2020

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“…methods are explained in [13][14][15] and in the Supplementary Material Supplementarymaterial.pdf (SM).…”

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confidence: 99%

Thunderstorm ground enhancements observed on Aragats mountain in Armenia in the wintertime

Chilingarian,

Hovsepyan,

Aslanyan

et al. 2023

EPL

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Thunderstorm ground enhancements comprise prominent peaks in the time series of particle fluxes originating from the electron-gamma avalanches in thunderclouds are observed in the Spring-Autumn seasons when the updraft of warm air cause hydrometeor charging in the cloud, and emerged electric field exceeds the runaway threshold strength. Suddenly, on February 7, 2023, particle detectors on Aragats registered 3 TGEs within 10 hours. Recovered energy spectra of TGE electrons and gamma rays prove nearly one hour the strength of the electric field above Aragats at the heights 3300-5300 m comprises ≈2.1 kV/cm. We present measured fluxes and energy spectra and modeling of the radar response based on the weather research and forecasting (WRF) model and discuss a wind-field model of cloud electrification in wintertime.

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Thunderstorm ground enhancements in Finland: observations using spectroscopic radiation detectors

Leppänen,

Peräjärvi,

Paatero

et al. 2024

Acta Geophys.

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This study reports observations of Thunderstorm Ground Enhancements (TGE) that occurred in Southern Finland in the Municipality of Vantaa (60° 18’ N 24° 58’ E at 55 m a.m.s.l) on May 17th, 2020 between 10:23 and 10:28 UTC. The TGEs occurred when a storm front moved across the Helsinki region from roughly a southwest to northeast direction. The TGEs were caused by a Runaway Relativistic Electron Avalanche (RREA) occurring inside a thundercloud. Three independent measuring units of high-volume NaI(Tl) γ spectrometers were used to record ambient dose rate and γ spectra. The observed TGEs manifested themselves as sudden increases in γ radiation on the ground with a wide range of energies from 100 keV up to the maximum of the detector system of 8.8 MeV. The first event lasted 50 s and produced an increase in γ radiation of about 7–12% in the spectra measured with a ten-second collection time. The enhancement in γ radiation was terminated suddenly and simultaneously with an in-cloud lightning strike. This was followed by an 88–100 s long period when the level of γ radiation returned to normal values. After this, a second enhancement was observed to increase the level of γ radiation by 20–50%. The second enhancement lasted 100 s and it was also terminated simultaneously with an in-cloud lightning flash. The second enhancement appears to be stronger, but the exact locations of the thundercloud emitting the γ radiation were not known. From the duration of the second enhancement and the prevailing wind speed, the size of the RREA was estimated to be 400–1000 m. In the second enhancement, the most intense increase was between 100 and 1000 keV, although very-high-energy γ rays was observed up to 8.8 MeV. The shape of the background-subtracted γ spectra agreed well with the observations and predictions of the shape of the bremsstrahlung spectrum emitted by an RREA. Additionally, in the background-subtracted spectra, a minor enhancement of the 511 keV peak was also observed where the RREA also increased the number of positrons which annihilated and increased the emission of the 511 keV γ rays. The results of these high-latitude, low-altitude TGE events are the first ones report in Finland.

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The horizontal profile of the atmospheric electric fields as measured during thunderstorms by the network of NaI spectrometers located on the slopes of Mt. Aragats

Cited by 8 publications

References 12 publications

Structure of thunderstorm ground enhancements

Structure of thunderstorm ground enhancements

Thunderstorm ground enhancements observed on Aragats mountain in Armenia in the wintertime

Thunderstorm ground enhancements in Finland: observations using spectroscopic radiation detectors

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