Gamma Ray Glow Observations at 20‐km Altitude

Østgaard, Nikolai; Christian, H. J.; Grove, J. E.; Sarria, David; Mezentsev, A. N.; Kochkin, P.; Lehtinen, N. G.; Quick, Mason G.; Al-Nussirat, S.; Wulf, E.; Genov, Georgi; Ullaland, K.; Marisaldi, M.; Yang, S.; Blakeslee, Richard J.

doi:10.1029/2019jd030312

Cited by 40 publications

(54 citation statements)

References 46 publications

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“…However, the large variability in duration, amplitude, and shape of TGEs detected by ASEC facilities, as well as, fluctuating patterns of the near-surface electrostatic field disturbances, allows also for other scenarios of the emergence of an electric field strong enough to accelerate electrons downwards. Recently, it was discovered that downward RREA (named gamma glow) occurred also between the negative screening layer and the upper positive charge layer just below it [8,35]. It is interesting to mention as well that examining the general characteristics of the preliminary breakdown and stepped leader processes, the authors of Ref.…”

Section: Electron Accelerator Operating In the Atmospherementioning

confidence: 99%

Origin of enhanced gamma radiation in thunderclouds

Chilingarian

Hovsepyan

Elbekian

et al. 2019

Phys. Rev. Research

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Natural gamma radiation (NGR), one of the major geophysical parameters directly connected with cloud electrification and lightning initiation, is highly enhanced during thunderstorms. At low energies below 3 MeV, the enhancement of NGR is due to natural isotope radiation, and for energies up to 50 MeV, it is due to the operation of the newly discovered electron accelerators in the thunderclouds. For the first time, we present a comprehensive model of the enhanced fluxes of radiation incident on the earth's surface during thunderstorms. In addition to the already explained minute-long fluxes of high-energy electrons and gamma rays from relativistic runaway electron avalanches (RREA), we clarify also the origin of hour-long isotropic fluxes of low-energy gamma rays from the Rn-222 progenies. Also, as a direct evidence of RREA, we present photographs of optical emission during the development of electron-gamma ray cascades in the atmosphere. Natural radioactivity is a source of continuous exposure of human beings to radiation. Radiation protection of living organisms requires an understanding of all sources and possible ways of enhancement of the radiation levels that can double for several hours in the energy domain of hundreds of keV. Therefore individual irradiation doses can be exceeded during thunderstorms. The models used for the forecasting of thunderstorms and other severe atmospheric phenomena need an accurate account of the ionizing radiation in the atmosphere. The airglows can influence the operation of optical, fluorescence, and atmospheric Cherenkov telescopes and fluorescence detectors.

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Section: Electron Accelerator Operating In the Atmospherementioning

confidence: 99%

Origin of enhanced gamma radiation in thunderclouds

Chilingarian

Hovsepyan

Elbekian

et al. 2019

Phys. Rev. Research

View full text Add to dashboard Cite

show abstract

“…The data acquisition system is similar to the one used in the Atmospheric Space Interaction Monitor (ASIM) mission and thoroughly described in Østgaard et al. (2019). The system has an intrinsic ability to identify the detector's saturation when subsequent counts start overlapping.…”

Section: Instrument and Datamentioning

confidence: 99%

“…The gamma‐ray glows were considered in detail in Østgaard et al. (2019). The thundercloud system where the glows originated from had a strong convection core.…”

Section: Observationmentioning

confidence: 99%

“…More on the spectra and effort to understand the origin of the emission can be found in Østgaard et al. (2019).…”

Section: Spectral Analysismentioning

confidence: 99%

“…This paper is an accompanying paper to Østgaard et al. (2019) where the gamma‐ray glows were reported and modeled. Here, we focus on the termination moment of the glow and analysis of the lightning flash that caused the termination.…”

Section: Introductionmentioning

confidence: 97%

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A Rapid Gamma‐Ray Glow Flux Reduction Observed From 20 km Altitude

et al. 2021

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Two gamma‐ray glows were observed by a high‐altitude NASA ER‐2 aircraft flying at 20 km altitude over a thunderstorm in Colorado, USA. The flux of the first glow rapidly intensified and then abruptly decreased within a few tens of milliseconds. On a timescale of seconds, the flux decrease occurred simultaneously with a hybrid intra‐cloud/cloud‐to‐ground lightning discharge beneath the aircraft. However, a more detailed analysis of the discharge dynamics indicated that the discharge activity was unusually calm during the actual period of the flux decrease. The lightning was observed with on‐board antennas, optical sensor, and ground‐based lightning mapping and location networks. Its closest activity was 12 km away from the aircraft, below and slightly ahead the course. The gamma‐ray flux reduction happened roughly in the middle of the lightning development process. The glow spectral analysis for the periods of a weak and strong flux enhancement has been done. The spectra were found to be background‐like and similar to each other.

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Library of simulated gamma-ray glows and application to previous airborne observations

Sarria

Østgaard

Marisaldi

et al. 2022

Preprint

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Gamma-Ray Glows (GRGs) are high energy radiation originating from thunderclouds, in the MeV energy regime, with typical duration of seconds to minutes, and sources extended over several to tens of square kilometers. GRGs have been observed from detectors placed on ground, inside aircraft and on balloons. In this paper, we present a general purpose Monte-Carlo model of GRG production and propagation. This model is first compared to a model from Zhou et al. ( 2016) relying on another Monte-Carlo framework, and small differences are observed. We then have built an extensive simulation library, made available to the community. This library is used to reproduce five previous gamma-ray glow observations, from five airborne campaigns: balloons from Eack et al. (1996b), Eack et al. (2000; and aircrafts from ADELE (Kelley et al., 2015), ILDAS (Kochkin et al., 2017) and ALOFT (Østgaard et al., 2019). Our simulation results confirm that fluxes of cosmic-ray secondary particles present in the background at a given altitude can be enhanced by several percent (MOS process), and up to several orders of magnitude (RREA process) due to the effect of thunderstorms' electric fields, and explain the five observations. While some GRG can be explained purely by the MOS process, E-fields significantly larger than E th (the RREA threshold) are required to explain the strongest GRGs observed. Some of the observations also came with in-situ electric field measurements, that were always lower than E th , but may not have been obtained from regions where the glows are produced. This study supports the claim that kilometer-scale E-fields magnitudes of at least the level of E th must be present inside some thunderstorms.

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Gamma Ray Glow Observations at 20‐km Altitude

Cited by 40 publications

References 46 publications

Origin of enhanced gamma radiation in thunderclouds

Origin of enhanced gamma radiation in thunderclouds

A Rapid Gamma‐Ray Glow Flux Reduction Observed From 20 km Altitude

Library of simulated gamma-ray glows and application to previous airborne observations

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