Characteristic Features of the Clouds Producing Thunderstorm Ground Enhancements

Svechnikova, Ekaterina; Ilin, N. V.; Mareev, E. A.; Chilingarian, A.

doi:10.1029/2019jd030895

Cited by 12 publications

(3 citation statements)

References 38 publications

(62 reference statements)

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“…The WRF model includes various parameterizations describing physical processes on a sub-grid scale. The set of parameterizations providing the most reliable modeling for clouds producing TGE observed at the Aragats Station is based on the recommendations for fine meshes (MP_PHYSICS = 8, RA_LW_PHYSICS = 4, RA_SW_PHYSICS = 4, RADT = 10, SF_SFCLAY_PHYSICS = 1, SF_SURFACE_PHYSICS = 2, BL_PBL_PHYSICS = 2) and a verification procedure using the results of near-surface measurement, and satellite data [35].…”

Section: Instrumentationmentioning

confidence: 99%

Transient Luminous Events in the Lower Part of the Atmosphere Originated in the Peripheral Regions of a Thunderstorm

et al. 2022

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We present and discuss transient luminous events (TLEs) in the lower atmosphere, observed during large disturbances of the near-surface electric fields (NSEF) and coinciding with large enhancements of the particle fluxes (thunderstorm ground enhancements—TGEs). Despite large distances from the strongest electric field region, the maximum energy of TGE particles on 22 and 25 May 2018 reaches ≈ 40 MeV. Thus, the accelerating electric field reaches ≈ 2.0 keV/cm far from the zone of the strong lightning activity on the periphery of the storm. Light glows appearing simultaneously in the skies may be due to the local charge rearrangement generating a small illuminating discharge without initiating the lightning flash. This type of charge rearrangement does not lower the potential difference in the cloud, allowing the electron accelerator to operate and send particle fluxes in the direction of the earth’s surface.

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Section: Instrumentationmentioning

confidence: 99%

Transient Luminous Events in the Lower Part of the Atmosphere Originated in the Peripheral Regions of a Thunderstorm

et al. 2022

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“…(Oklahoma, USA),Takahashi et al (2019);Zheng et al (2018) (Japan),Takahashi et al (1999) (Micronesia),Li et al (2020) (Tibetan Plateau, China), andSvechnikova et al (2021); Armenia). The examination of reflectivity structure directly over regions characterized by electron runaway and enhanced flux of gamma radiation in the present study serves to focus attention on the storm generator that is productive to the most intense electric field (of either polarity).…”

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confidence: 99%

Radar Diagnosis of the Thundercloud Electron Accelerator

et al. 2022

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Thunderstorm Ground Enhancements (TGEs) refer to correlated enhancements in surface electric field and gamma ray flux that are manifestations of electron runaway in the storm overhead. The electric field enhancements can be of positive or negative polarity. In this study, altitude‐resolved S‐band radar observations of graupel are used to demonstrate distinct differences in storm structure linked with these “positive” and “negative” TGEs. The physical interpretation rests on the well‐established temperature‐dependent tripole structure of thunderstorms, with the main negative charge of the tripole acting as an electron repeller. This interpretation is supported by case studies showing altitude‐stable convection, with shallow (deep) development linked with “positive” (“negative”) TGEs, and by case studies of collapsing storms that show upper dipole dominance early and lower inverted dipole dominance later when graupel particles descend from a colder to warmer temperature domain. In the case of many TGEs on Mt Aragats (3.2 km MSL), the temperature‐dependent altitude of downward electron acceleration and avalanching may be sufficiently distant (>500 m) from surface detectors that the energetic electrons (1–10 MeV) are not likely avalanche/runaway electrons. Instead, they are Compton‐scattered and pair‐produced electrons from bremsstrahlung gamma radiation emanating from the high‐field avalanche region aloft. These inferences are consistent with GEANT4 calculations that identify the physical origins of energetic electrons at the surface.

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“…We introduce a uniform electric field in the gap of 200-2200 above particle detectors (corresponding to 3400-5400 m a.s.l.). The heights of 2000-3000 m above the station are typical for the location of the main negatively charged layer of the thundercloud [20]. Thus, we assume in this study a maximum 2000 m extension of the electric field.…”

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confidence: 99%

Measurement of TGE particle energy spectra: An insight in the cloud charge structure

Chilingarian

Hovsepyan

Zazyan

2021

EPL

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In this letter, we present for the first time the method to get insight into the charge structure of the thundercloud using simultaneously measured electron and gamma-ray energy spectra of the thunderstorm ground enhancement (TGE). We discuss and compare two main scenarios that can support the initiation of the relativistic runaway electron avalanches (RREA) in the thundercloud. One of the scenarios includes the emergence of the lower positive charged layer (LPCR). The LPCR is a short-living charge structure sitting on hydrometeors, which exhibit accidental charge reversals depending on temperature changes. LPCR can sustain a downwards directed near-surface electric field for several minutes, before falling down with precipitation. Recently, we launched on Aragats a large spectrometer, which is capable to measure energy spectra of electrons and gamma-rays in the energy range from 4 to 100 MeV. Comparison of energy spectra of electrons and gamma-rays makes it possible to scrutinize the LPCR emergence and estimate the height where the strong electric field that originates the RREA terminates.

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Characteristic Features of the Clouds Producing Thunderstorm Ground Enhancements

Cited by 12 publications

References 38 publications

Transient Luminous Events in the Lower Part of the Atmosphere Originated in the Peripheral Regions of a Thunderstorm

Transient Luminous Events in the Lower Part of the Atmosphere Originated in the Peripheral Regions of a Thunderstorm

Radar Diagnosis of the Thundercloud Electron Accelerator

Measurement of TGE particle energy spectra: An insight in the cloud charge structure

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