The upper cut-off frequency of nose whistlers and implications for duct structure

Strangeways, H.J.

doi:10.1016/0021-9169(91)90028-6

Cited by 19 publications

(9 citation statements)

References 55 publications

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“…At the same time, the other example of time dependence of the polarization angle, shown in Figure 5, does not happen within the structured interval itself but includes a handful of QP elements spanning several minutes at a time. We suggest that this could be the result of the changing wave duct structure between the source in the magnetosphere and the ionospheric exit point of the emission, and not a direct consequence of the movement of the magnetospheric source (e.g., Strangeways (1991)). It was believed that bursty-patches, first reported by Shiokawa et al (2014), might be the upper frequency band of chorus emissions.…”

Section: Vlf/elf Emissions' Characteristicsmentioning

confidence: 89%

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Martinez-Calderon

Shiokawa

Ozaki

et al. 2015

Earth, Planets and Space

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Chorus wave emissions are one of the most intense naturally occurring phenomena in the very low (VLF) and extremely low frequency (ELF) ranges. They are believed to be one of the major contributors to acceleration and loss of electrons in the radiation belts. During the VLF Campaign observation with High-resolution Aurora Imaging Network (VLF-CHAIN) from 17 to 25 February 2012, several types of VLF/ELF emissions, including chorus, were observed at subauroral latitudes in Athabasca, Canada. To our knowledge, there has not been any comprehensive study of the physical properties of such emissions at these latitudes. In this study, we calculate spectral and polarization parameters of VLF/ELF waves with high temporal resolution. We found that the polarization angle of several emissions depended on both frequency and time. We suggest that the frequency-dependent events, which usually last several tens of minutes, might be the consequence of the broadening of the ray path that the waves follow from their generation region to the ground. Furthermore, time-dependent events, also lasting tens of minutes, have a polarization angle that changes from negative to positive values (or vice versa) every few minutes. We suggest that this could be due to variations of the wave duct, either near the generation region or along the wave propagation path. Using another ground station in Fort Vermillion, Canada, about 450 km northwest of Athabasca, we tracked the movements of the ionospheric exit point of three chorus emissions observed simultaneously at both stations. Although we found that movement of the ionospheric exit point does not follow a general direction, it is subject to hovering motion, suggesting that the exit point can be affected by small-scale plasma processes.

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Section: Vlf/elf Emissions' Characteristicsmentioning

confidence: 89%

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Martinez-Calderon

Shiokawa

Ozaki

et al. 2015

Earth, Planets and Space

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“…N everthe less the res id ua ls are fairly sm all (less th an a t -o e t e m ( 1 --1 -o -1 -) t a n o h c about 3 ins) for small I ( < g X 10-4 ). The residuals would athi-Lorentz term s Iass-u10d to -e 10-3) thanster hich r also be significantly smaller for any given value of I for a t signfiently emistortued eto r rger Whislespfc-ra are plasmasphere model with a faster rate of falloff of electron n o gnficatl wit oteceptl dsorto ervaus ofepe:dh density along the field line as would occur if a realistic temvlo f 1 faorielctro nity.able distr btion or depeds perature gradient were incorporated [Strangeways, 1986] or of theequatorialefhtler deity. he rond of upper if a collisionless rather thin diffusive equilibrium model were ctof freqencie of whiter ariedion thign d at or -n dI considered.…”

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confidence: 93%

“…Consider a whistler-mode wave propagating in a crest of Strangeways [1991a] considers in detail the upper cutoff freionization. For the wave to remain ducted, assuming the duct quency of whistlers as measured experimentally and as would…”

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confidence: 99%

Publication of Papers Presented at URSI 23RD General Assembly as a Special Section of Radio Science

Yeh¹

1992

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Public reporting burden for this collection Of information fl i estimated to averge I hour OW response. including the time for rev-ewing instructions. searching exsting date sources. gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of thts collection of informatiOn. including sugg"tio for reducing this burden. to washington Heaquartes Services. Directorate for information Operations and Reports. 121S Jefferson Oavis Highway. Suite 1204. Arlington. VA 22202-4302. and Approved for public release; distribution unlimited. ABSTRACT (Maximum 200 words)A symposium entitled "Radio Propagation in the Ionosphere and Magnetosphere: Theory and Application" was convened at the 23rd General Assembly of URSI, August 28 through September 5, 1990. Of-the 49 papers presented at this symposium, 13 were selected for publication in Radio Science, Volume 27, Number 2, March-April 1992.These papers cover a broad field of ionospheric and magnetospheric propagation of both experimental and theoretical nature. At the 23rd General Assembly (GA) of the International Union of Radio Science (URSI) held in Prague, Czechoslovakia, August 28 through September 5, 1990, a Joint Symposium 2 (JS2), cosponsored by Commissions G and H of URSI, was convened. This symposium was entitled "Radio Propagation in the Ionosphere and Magnetosphere: Theory and Application." The undersigned were appointed as conveners by Commission G Chair, Henry Rishbeth, and Commissio. H Chair, Hiroshi Matsumoto. For this symposium, altogether 49 papers were received and presented by authors from 12 countries around the world. The richness and diversity of the work marked a milestone of our progress in this field. Many scientific leaders in the radio science community felt that it was perhaps a good opportunity to collect these papers and have them published in one journal as a special section. After a survey of all authors, strong interest had been expressed in publishing them in Radio Science. With the strong support of the authors and the Editors of Radio Science we proceeded to contact the authors and to process the papers after having received them.The papers presented at the JS2 of URSI GA covered a vast field. In terms of geographic regions, propagation paths under study took place in high latitudes where the auroral ionosphere, under the perpetual influence of penetrating convective electric fields of magnetospheric origin, was often very disturbed, or in equatorial latitudes where the ionosphere was subject to equatorial dynamics and plasma instabilities, or over long paths traversing many different regions of the globe. In terms of wave frequencies the waves could be in the VLF band propagating in the Earthionosphere waveguide mode; they could also be ion cyclotron waves and whistler waves which were slowly propagating and highly dispersive; they could also be in the HF to SHF bands where effects produced by the inhomogeneous and anisotropic natur...

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“…These measurements demonstrate that parameters of magnetospheric ducts change over a very wide range: the radius of a duct can be from tens to hundreds of kilomeCorrespondence to: D. L. Pasmanik (pdl@aurora.appl.sci-nnov.ru) ters, and the density enhancement changes from fractions of ambient plasma density up to multiple increases in the case of a duct located outside the plasmasphere. It is clear that in the case when the duct radius is much greater than the characteristic wavelength the ray-tracing method is applicable (Strangeways, 1991(Strangeways, , 1999. But if the duct radius is comparable with the wavelength it is necessary to perform a more strict analysis and to study the actual spatial structure and dispersion properties of waves propagating in a duct.…”

Section: Introductionmentioning

confidence: 99%

“…The possibility of whistler mode wave trapping in the density duct was studied in many papers, see, for example, Helliwell (1965); Karpman and Kaufman (1982); Strangeways (1991). It is well known that whistler-wave trapping is possible in the ducts of enhanced plasma density in the frequency range ω<ω B /2, where ω B is the electron gyrofrequency.…”

Section: Introductionmentioning

confidence: 99%

Dispersion properties of ducted whistlers, generated by lightning discharge

Pasmanik

Trakhtengerts

2005

Ann. Geophys.

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Abstract. Whistler-mode wave propagation in magnetospheric ducts of enhanced cold plasma density is studied. The case of the arbitrary ratio of the duct radius to the whistler wavelength is considered, where the ray-tracing method is not applicable. The set of duct eigenmodes and their spatial structure are analysed and dependencies of eigenmode propagation properties on the duct characteristics are studied. Special attention is paid to the analysis of the group delay time of one-hop propagation of the whistler wave packet along the duct. We found that, in contrast to the case of a wide duct, the group delay time in a rather narrow duct decreases as the eigenmode number increases. The results obtained are suggested for an explanation of some types of multi-component whistler signals.

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The upper cut-off frequency of nose whistlers and implications for duct structure

Cited by 19 publications

References 55 publications

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign

Publication of Papers Presented at URSI 23RD General Assembly as a Special Section of Radio Science

Dispersion properties of ducted whistlers, generated by lightning discharge

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