Rapid onset, rapid decay (RORD), phase and amplitude perturbations of VLF subionospheric transmissions

Dowden, R. L.; Adams, Charles C.; Brundell, James B.; Dowden, P.E.

doi:10.1016/0021-9169(94)90118-x

Cited by 73 publications

(60 citation statements)

References 17 publications

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“…[5] At Ny Å lesund, Svalbard, (78°54 0 N, 11°53 0 E, L $ 18) a narrowband VLF Omnipal receiver was used to monitor the signals from several high-power transmitters located in the Northern Hemisphere [Dowden et al, 1994;Clilverd et al, 2001]. We make use of the received amplitude of VLF signals to characterize the response of the upper atmosphere to SPE produced ionization changes.…”

Section: Experimental Configuration and Event Conditionsmentioning

confidence: 99%

Modeling polar ionospheric effects during the October–November 2003 solar proton events

et al. 2006

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[1] At Ny Å lesund, Svalbard (78°54 0 N, 11°53 0 E, L $ 18), a narrowband VLF receiver was used to monitor the behavior of the amplitude of several high-power transmitters located in the Northern Hemisphere under the influence of the solar proton events (SPE) of October/November 2003. We have used Sodankylä ion chemistry (SIC) atmospheric model profiles calculated at the midpoint location of the propagation paths in the northern wintertime polar region to investigate the radio propagation properties of several highlatitude paths. Different paths showed different responses to the proton precipitation, but propagation modeling was broadly able to account for most of the positive and negative responses observed. Using the SIC-based electron density profiles, we have been able to develop models of ionospheric effective height (h 0 ) and sharpness (b) in order to describe the D region behavior as a function of proton flux, extending previous work which reported b and h 0 values as functions of the X-ray flux from solar flares. As a result of these models, our understanding of VLF propagation influenced by SPEs is such that VLF observations might be used to predict changes in the ionospheric D region electron density profiles during other particle precipitation events.

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Section: Experimental Configuration and Event Conditionsmentioning

confidence: 99%

Modeling polar ionospheric effects during the October–November 2003 solar proton events

et al. 2006

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“…While some initial evidence [Dowden et al, 1994] suggested that VLF sprites consisted of two distinct, separated regions of ionization (one at relatively low altitudes which rapidly decayed and a higher-altitude region with considerably longer persistence time), recent observations [Dowden et al, 1997] indicate a single, but changing scatterer for what was earlier thought of as separate components. The continuous nature of the decay was masked by random fluctuations (noise) in earlier observations.…”

Section: Introductionmentioning

confidence: 96%

Relaxation of transient ionization in the lower ionosphere

Rodger¹,

Molchanov²,

Thomson³

1998

J. Geophys. Res.

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Abstract. This paper presents a set of basic expressions and parameters to describe the relaxation of ionization in the upper atmosphere and lower ionosphere. Both spatial (diffusion) and chemical loss are included, along with the varying electrical conductivity caused by changing electron density and temperature. In particular, masonable values for the attachment rates and recombination coefficients at these high altitudes are discussed. Example calculations are given involving studies into red sprites. However, the modeling and parameters are not restricted to these events, and might well be useful in a number of other modeling problems.

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“…Discovery of the "early/fast" Trimpi [Armstrong, 1983], which onsets too soon ("early") after the initiating lightning to be produced by electron precipitation and reaches-full perturbation rapidly ("fast"), showed that these Trimpis are directly caused by lightning. Observations on spaced receivers [Dowden et al, 1994] showed that "early/fast" Trimpis consist of two components arriving from measurably different directions: a rapid onset, rapid decay (RORD) component and a slow onset, slow Copyright 1997 by the American Geophysical Union.…”

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Temporal evolution of very strong Trimpis observed at Darwin, Australia

Dowden

Brundell

Rodger

1997

Geophysical Research Letters

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Abstract.Very strong phase and amplitude perturbations (Trimpis) of the very strong VLF transmission from NWC received in Darwin, Australia, enabled accurate measurement of the amplitude and phase of the scattered signal and of the time variation of these. The amplitude of the scattered signal decays as the logarithm of time, quite at odds with the exponential decay observed on classic Trimpis. During the amplitude decay, the phase of the scattered signal decreased at a decreasing rate. This is shown to be consistent with scattering from a bundle of sprite-like, conducting columns extending some 50 km below the base of the ionosphere.

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Rapid onset, rapid decay (RORD), phase and amplitude perturbations of VLF subionospheric transmissions

Cited by 73 publications

References 17 publications

Modeling polar ionospheric effects during the October–November 2003 solar proton events

Modeling polar ionospheric effects during the October–November 2003 solar proton events

Relaxation of transient ionization in the lower ionosphere

Temporal evolution of very strong Trimpis observed at Darwin, Australia

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