Effects of thunderstorm‐driven runaway electrons in the conjugate hemisphere: Purple sprites, ionization enhancements, and gamma rays

Lehtinen, N. G.; Inan, U. S.; Bell, T. F.

doi:10.1029/2000ja000160

Cited by 56 publications

(66 citation statements)

References 46 publications

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“…It is pertinent to note that the characteristics of the terrestrial g ray flashes detected in the near space aboard CGRO [Fishman et al, Table 1. Number, Flux Density, and Fluence of Neutrons at the "Detector Altitude" for Neutron Source Located at "Cloud Altitude" 1994] and RHESSI are explained more or less adequately by bremsstruhlung of ascending relativistic electron avalanches (for instance, [Dwyer and Smith, 2005;Dwyer, 2008;Cummer et al, 2005;Williams et al, 2006;Babich et al, 2007b;2008a, 2008b, 2008c), as in the earlier works, where the CGRO data were analyzed [e.g., Taranenko and Roussel-Dupre, 1996;Roussel-Dupre et al, 1998;Lehtinen et al, 1996Lehtinen et al, , 1999Lehtinen et al, , 2001Gurevich and Zybin, 2001;Babich et al, 2001Babich et al, , 2004b.…”

Section: Discussionmentioning

confidence: 81%

Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere

et al. 2010

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[1] To localize an altitude of the neutron source responsible for the neutron flux enhancements observed on the ground, numerical simulations of photonuclear production and transport to on-ground detector locations were carried out. The neutron fluence calculated for the volumetric source located at the altitudes 8-12 km is consistent with that estimated from neutron numbers measured on the ground. This altitude range is consistent with the idea that the burst of hard g rays detected recently by Tsuchiya et al. (2007Tsuchiya et al. ( , 2009 originate from a volumetric intracloud g ray source. Most likely, the photonuclear reactions caused by bremsstruhlung of descending relativistic runaway electron avalanches account for the neutron flux increases observed in the thunderstorm atmosphere.Citation: Babich, L. P., E. I. Bochkov, I. M. Kutsyk, and R. A. Roussel-Dupré (2010), Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere,

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Section: Discussionmentioning

confidence: 81%

Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere

et al. 2010

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“…However, even if only ∼3 to 10% of the electrons precipitate on the conjugate atmosphere, they create detectable emissions via interactions with atmospheric species. For 500 C of charge removed from 15 km altitude (M q =7500 C-km), consistent with the largest observed gamma-ray fluxes, the injected beam density is N e =10 5 m −3 , and the predicted emissions should be of a similar magnitude to elves (Lehtinen et al, 2001). While this charge moment is very high compared to observed values (e.g., Cummer and Inan, 2000), it results in a relativistic beam density that is consisted with BATSE gamma-ray flash observations (Lehtinen et al, 2001).…”

Section: Introductionmentioning

confidence: 85%

“…However, the beam may undergo pitch angle scattering and energy degradation during its traverse, through wave-particle resonance interactions, so that only a fraction of electrons remain in the loss cone. In the worst case, when pitch angles are scattered into an isotropic distribution, the number in the loss cone is a function of geomagnetic latitude; at latitudes of 30-40 deg, this number varies from 10 down to 3% (Lehtinen et al, 2001). However, even if only ∼3 to 10% of the electrons precipitate on the conjugate atmosphere, they create detectable emissions via interactions with atmospheric species.…”

Section: Introductionmentioning

confidence: 99%

“…A 1-D fully electrodynamic model developed by Lehtinen et al (2001) predicts the formation of a beam of relativistic electrons propagating away from the thundercloud and into the magnetosphere, where the electron trajectories are confined to magnetic field lines. Following the charge removal by the +CG, a quasi-electrostatic field is established between the cloud and the ionosphere above it.…”

Section: Introductionmentioning

confidence: 99%

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Optical observations geomagnetically conjugate to sprite-producing lightning discharges

et al. 2005

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Abstract. Theoretical studies have predicted that large positive cloud-to-ground discharges can trigger a runaway avalanche process of relativistic electrons, forming a geomagnetically trapped electron beam. The beam may undergo pitch angle and energy scattering during its traverse of the Earth's magnetosphere, with a small percentage of electrons remaining in the loss cone and precipitating in the magnetically conjugate atmosphere. In particular, N 2 1P and N + 2 1N optical emissions are expected to be observable. In July and August 2003, an attempt was made to detect these optical emissions, called "conjugate sprites", in correlation with sprite observations in Europe near L 1.78. Sprite observations were made from the Observatoire du Pic du Midi (OMP) in the French Pyrenées, and VLF receivers were installed in Europe to detect causative sferics and ionospheric disturbances associated with sprites. In the Southern Hemisphere conjugate region, the Wide-angle Array for Sprite Photometry (WASP) was deployed at the South African Astronomical Observatory (SAAO), near Sutherland, South Africa, to observe optical emissions with a field-of-view magnetically conjugate to the Northern Hemisphere observing region. Observations at OMP revealed over 130 documented sprites, with WASP observations covering the conjugate region successfully for 30 of these events. However, no incidences of optical emissions in the conjugate hemisphere were found. Analysis of the conjugate optical data from SAAO, along with ELF energy measurements from Palmer Station, Antarctica, and charge-moment analysis, show that the lightning events during the course of this experiment likely had insufficient intensity to create a relativistic beam.

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“…Some problems arise because the runaway theory predicts that the lightning charge moment change needs to be about 5000 C km to generate the runaway breakdown at the altitude range 30-50 km followed by the TGFs events (Lehtinen et al, 2001). This contradicts with observations since the measured lightning charge moment changes in TGF-associated strokes are 50-500 times smaller than what the runaway theory predicts (Cummer et al, 2005).…”

Section: V Surkov and M Hayakawa: Underlying Mechanisms Of Transmentioning

confidence: 99%

Underlying mechanisms of transient luminous events: a review

Сурков

Hayakawa

2012

Ann. Geophys.

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Abstract. Transient luminous events (TLEs) occasionally observed above a strong thunderstorm system have been the subject of a great deal of research during recent years. The main goal of this review is to introduce readers to recent theories of electrodynamics processes associated with TLEs. We examine the simplest versions of these theories in order to make their physics as transparent as possible. The study is begun with the conventional mechanism for air breakdown at stratospheric and mesospheric altitudes. An electron impact ionization and dissociative attachment to neutrals are discussed. A streamer size and mobility of electrons as a function of altitude in the atmosphere are estimated on the basis of similarity law. An alternative mechanism of air breakdown, runaway electron mechanism, is discussed. In this section we focus on a runaway breakdown field, characteristic length to increase avalanche of runaway electrons and on the role played by fast seed electrons in generation of the runaway breakdown. An effect of thunderclouds charge distribution on initiation of blue jets and gigantic jets is examined. A model in which the blue jet is treated as upward-propagating positive leader with a streamer zone/corona on the top is discussed. Sprite models based on streamer-like mechanism of air breakdown in the presence of atmospheric conductivity are reviewed. To analyze conditions for sprite generation, thunderstorm electric field arising just after positive cloudto-ground stroke is compared with the thresholds for propagation of positively/negatively charged streamers and with runway breakdown. Our own estimate of tendril's length at the bottom of sprite is obtained to demonstrate that the runaway breakdown can trigger the streamer formation. In conclusion we discuss physical mechanisms of VLF (very low frequency) and ELF (extremely low frequency) phenomena associated with sprites.

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Effects of thunderstorm‐driven runaway electrons in the conjugate hemisphere: Purple sprites, ionization enhancements, and gamma rays

Cited by 56 publications

References 46 publications

Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere

Localization of the source of terrestrial neutron bursts detected in thunderstorm atmosphere

Optical observations geomagnetically conjugate to sprite-producing lightning discharges

Underlying mechanisms of transient luminous events: a review

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