Models of lightning‐produced sprites and elves

Fernsler, R. F.; Rowland, H. L.

doi:10.1029/96jd02159

Cited by 49 publications

(40 citation statements)

References 20 publications

(18 reference statements)

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“…The observed initiation height, •>300 C.km parent discharge charge moment changes [Cureruer and Huang et al, 1999], and corona streamer characteristics [Stanley et al, 1999a] are consistent with a conventional breakdown mechanism for sprite initiation and development under the influence of a CG's quasi-electrostatic field [Wilson, 1925;Fernsler and Rowland, 1996;Pasko et al, 1998]. During the daytime, ionospheric conductivity is greatly enhanced at the altitudes of nighttime sprite initiation.…”

mentioning

confidence: 68%

Detection of daytime sprites via a unique sprite ELF signature

Stanley¹,

Brook²,

Krehbiel³

et al. 2000

Geophysical Research Letters

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Abstract. On August 14, 1998, 3 separate daytime sprite events were detected via a unique extremely low frequency (ELF) sprite signature. The onset of the sprite ELF signatures was delayed by 11.0-13.2 ms from positive cloudto-ground strokes which had attained exceptionally large charge moment (charge times height) changes of 3900-6100 C-km. It is shown that a charge moment change of 6100 C.km may have been sufficient for conventional breakdown at _•54 km altitude, assuming an experimentally measured ion conductivity profile of Holzworth et al., [1985].The daytime sprites themselves contained unusually large charge moment changes of _•2800 C.km, ___1200 C.km, and m910 C-km. IntroductionSprites are luminous discharges which photometrically have only been documented at night in part because of the dominance of Rayleigh scattering of sunlight during the day. were correlated with bright sprites on video but were temporally distinct from +CG slow tails. These slow field changes were unique in that they were not immediately preceded by the very low frequency (VLF) radiation produced by a In this paper, we report the first detection of daytime sprite events via their ELF "fingerprint". It will be shown that the value of the parent discharge charge moments at the onset of the daytime sprite ELF signatures is much greater than for the onset of nighttime sprite ELF signatures. InstrumentationThe GPS-based NMT radio atmospheric (sferic) system was used to acquire very broadband (<1 Hz-250 kHz) electric field data. Pre-and post-trigger data of a combined fixed length was stored at a 500 kHz sample rate whenever a bipolar threshold was exceeded. The system was able to immediately rearm after the post-trigger was stored. This feature, combined with a high data bandwidth, translated into a 100% detection efficiency for all sferics which met the sensitive trigger criteria. This resulted in an unambiguous identification of CG occurrence, making it possible to discriminate between slow tails which are associated with CGs and delayed slow field changes associated with sprites. The preand post-trigger lengths were configurable, but were set to 2 and 6 ms respectively on August 14, 1998. The electric field data was also stored continuously at a 10 kHz sample rate.The NMT sferic system was located on a mountain ridge at Langmuir Laboratory, NM. In order to determine the electric field intensification due to the ridge, sferics at >800 km range were compared between the NMT sferic system and an electric field sferic system located ___30 km away on level terrain. This comparison revealed that the ridge intensified the electric field by a factor of 1.9+0.2. The NMT system's electric field values were converted to fiat terrain values and these were used for the ELF propagation model. Analysis methodThe lightning current moment (current times vertical channel length) was extracted quantitatively by a tech- 871

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confidence: 68%

Detection of daytime sprites via a unique sprite ELF signature

Stanley¹,

Brook²,

Krehbiel³

et al. 2000

Geophysical Research Letters

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“…Haldoupis et al (2009), from a modeling study on the relaxation of early VLF events associated with TLEs, have shown that events with shorter recoveries are likely to come from lower altitudes compared with events with longer recoveries. Also it has been estimated that an unusually large charge moment change of about 8000 C-km is required to initiate a daytime sprite at a 50-km altitude (Fernsler and Rowland, 1996). Stanley et al (2000) detected 3 separate daytime sprites on 14 August, 1998, via a unique sprite ELF signature recorded at a site in New Mexico, following exceptionally large lightning discharges.…”

Section: Resultsmentioning

confidence: 99%

Lightning-associated VLF perturbations observed at low latitude: Occurrence and scattering characteristics

Kumar

2013

Earth Planet Sp

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The occurrence of short-timescale (∼1-100 s) perturbations (early VLF events) on four Very Low Frequency (VLF) transmitter signals (call signs: NWC, NPM, VTX, NLK), recorded at Suva (18.1• S, 178.5• E, L = 1.16), shows the most frequent occurrence on the NWC signal and least on the VTX. Daytime early/fast events on the NWC transmission are (0.2-0.5 dB) with only negative amplitude perturbations with comparatively lower recovery times (10-30 s) as compared with most nighttime events with amplitude perturbations of 0.2-1.5 dB and recovery times of 20-80 s. The World-Wide Lightning Location Network detected causative lightnings for 74 of 453 early VLF events out of which 54 (73%) were produced due to narrow-angle scattering, and by 20 (27%) due to wide-angle scattering. The recovery (decay) of the scattered amplitude of early/fast events on the NWC signal shows both exponential and logarithmic forms, but the linear correlation coef cient is better with a logarithm t. The rst observations of early/slow events in daylight propagation are presented. Initial results on early/fast events with unusually long recoveries (≥5 min) and strong perturbations (≥1 dB) indicate that they are mainly observed on the transmissions from NPM and NLK in the nighttime only, with rare occurrence on other transmissions. Such unusually long recovery of early/fast events may be associated with large ionic conductivity perturbations associated with gigantic jets.

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“…These electric fields may accelerate thermal electrons to energies of a few eV which are required to generate light and ionization (conventional breakdown) [Fernsler and Rowland, 1996; 1997], and they may also accelerate MeV electrons produced by cosmic rays into an upward propagating, avalanching beam of runaway electrons (runaway breakdown) [Lehtinen et al, 1997;Yukhirnuk et al, 1998]. A critical parameter in each of these theories is the electric charge moment change created by the parent lightning discharge, which is directly related to the quasi-static mesospheric electric field thought to be the driving force in sprite generation.…”

Section: Introductionmentioning

confidence: 99%

Submillisecond resolution lightning currents and sprite development: Observations and implications

Cummer

Stanley

1999

Geophysical Research Letters

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Abstract. We analyze synchronized high speed video images and ELF-VLF radio emissions from 11 sprite clusters observed on 6 October 1997. Quantitative analysis shows that vertical lightning charge moment changes of 150-1100 C.km occurred before the optical emissions reached their peak with delays of 2-11 ms from the lightning discharge. This threshold unexpectedly decreases with increasing delay from parent lightning to peak emissions. We also find that sprite charge moment change and minimum sprite altitude are not well correlated with the vertical charge moment change in the parent discharge. These observations do not agree well with present sprite generation models, and we suggest that streamer development and horizontal lightning charge motion can play a significant role in sprite generation.

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Models of lightning‐produced sprites and elves

Cited by 49 publications

References 20 publications

Detection of daytime sprites via a unique sprite ELF signature

Detection of daytime sprites via a unique sprite ELF signature

Lightning-associated VLF perturbations observed at low latitude: Occurrence and scattering characteristics

Submillisecond resolution lightning currents and sprite development: Observations and implications

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