Temporal evolution of very strong Trimpis observed at Darwin, Australia

Dowden, R. L.; Brundell, James B.; Rodger, Craig J.

doi:10.1029/97gl02357

Cited by 35 publications

(23 citation statements)

References 9 publications

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“…We have made use of an experimentally observed assembly of spritelet columns, spread over a region of -800 km 2. The first model used in our calculations is that of Rodger et al [1997a, b], which represents each spritelet as an electrically thin infinite column of constant conductivity. The analysis requires that column radius be much less than a wavelength, a condition which is amply satisfied for red sprite research [Rodger et al, 1998a].…”

Section: Discussionmentioning

confidence: 99%

“…In particular, the theoretical expressions developed by Rodger et al [1997a, b] (hereinafter referred to as R97) have been applied to red sprites [Rodger et al, 1998a, b] by including many vertical columns of ionization, each with a height-independent conductivity of between 0.1 and 10 mS m -1, to determine the effects on VLF wave propagation. The calculations indicated very complex scattering patterns, with deep nulls in some directions where no perturbation would be observed, and in some cases backscattered field strengths of magnitudes similar to those for forward scattering.…”

mentioning

confidence: 99%

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VLF scattering from red sprites: Application of numerical modeling

Rodger¹,

Nunn²

1999

Radio Science

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

VLF scattering from red sprites: Application of numerical modeling

Rodger¹,

Nunn²

1999

Radio Science

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“…~ An important discovery, of relevance in the theory discussion later, is that the magnitude of the scatterkd wave in any one event decays logarithmically with time, at lea& for times f > 0.2 s after onset of the Trimpi [17]. This behavior (is a consequence [18] of the electron-density decay rate decreasing exponentially with altitude with a scale height of about 3.5 kin.…”

Section: Estimate Of Reflection Coefficientmentioning

confidence: 95%

Minimum sprite plasma density as determined by VLF scattering

Dowden¹,

Rodger

Nunn

2001

IEEE Antennas Propag. Mag.

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The scattering of VLF sub-ionospheric transmissions by sprite plasma through horizontal angles up to 180" shows that sprite plasma is highly conducting. Following a simple transmission-line (one-dimensional-wave) model in 1997, two-dimensional and three-dimensional models have been produced. Here, we compare the results of the three models, and show that all require a uniform conductivity of at least 30 pS/m, corresponding to an electron density at 70 km altitude of -10" m-3 (-IO4 electrons per cc), and so about 105/cc at 55 km. The latter ionization density is about that of the daytime E-region, and over six orders of magnitude above the ambient density at 55 km. By contrast, the "earlylfast" events, as defined by the Stanford group, do not exhibit scatter angles above 15", suggesting that the sprite conductivity rises too slowly (as the plasma cools) to reach adequate backscatter within the time allowed by the "early/fast" definition.

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“…Echo signal is calculated by vector subtraction of a reference background, y ref , from the ionospheric signal (see inset of Figure 4d). This method is used in the analysis of lightning-induced ionospheric perturbations (e.g., Dowden et al, 1997;Kotovsky & Moore, 2015) and combines the amplitude and phase of the ionospheric signal. Here, the reference ionospheric background y ref is taken as the ionospheric signal just before the disturbance at 11:49 UTC.…”

Section: Thunderstorm and Lightning Activitymentioning

confidence: 99%

Lower Ionospheric Conductivity Modification Above a Thunderstorm Updraught

et al. 2019

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Lightning has previously been observed to disturb the lower ionosphere. These lightning‐induced ionospheric perturbations were observed as disturbances on subionospheric low‐frequency radio wave propagation with fast rise times <3 s and gradual recoveries of duration >10 s. Most of these disturbances were observed during night time when ionospheric conditions are most favorable. Here, a daytime perturbation in the lower ionosphere was observed using subionospheric radio remote sensing. The disturbance exhibits a ∼60 s rise time with a gradual recovery of >200 s. No cloud to ground lightning was coincident with the disturbance onset, however, the intracloud lightning activity of a thunderstorm over the radio receiver was seen to increase at the time of the disturbance. Therefore, the observed disturbance is unlikely to be caused by lightning, yet appears to be associated with the thunderstorm. It is proposed that this disturbance is produced by a pronounced increase in updraught strength that produced a significant change in the quasi‐static electrification of the thunderstorm. This change in electrification is evident in the increase in the intracloud lightning activity of the thunderstorm. The observation provides further evidence of the ionospheric heating effect of thundercloud charge which has implications for lower atmosphere‐ionosphere energy coupling and possibly sprite initiation.

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Temporal evolution of very strong Trimpis observed at Darwin, Australia

Cited by 35 publications

References 9 publications

VLF scattering from red sprites: Application of numerical modeling

VLF scattering from red sprites: Application of numerical modeling

Minimum sprite plasma density as determined by VLF scattering

Lower Ionospheric Conductivity Modification Above a Thunderstorm Updraught

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