Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

Baransky, L.; Green, A. W.; Fedorov, E. N.; Kurneva, N. A.; Pilipenko, Vyacheslav; Worthington, E. William

doi:10.5636/jgg.47.1293

Cited by 18 publications

(20 citation statements)

References 26 publications

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“…First, due to the specific polarization asymmetry of resonant amplification of field line oscillations at mid-latitudes, the H component is enhanced in comparison to the D component. This fact is already used for the extraction of the resonant frequency from complicated ULF spectra in the socalled H/D polarization method (Baransky et al, 1995). A similar asymmetry is not expected to be observed for the cusp-associated Pc3.…”

Section: Discussionmentioning

confidence: 81%

Magnetohydrodynamic waveguide/resonator for Pc3 ULF pulsations at cusp latitudes

et al. 2014

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We present a possible theoretical model for the generation of travelling Alfven waves by external compressional disturbances in a two-dimensional inhomogeneous plasma. The transformation of a compressional wave mode into Alfven waves guided by the magnetic field is considered in a region with decreased Alfven velocity. This region represents, on the one hand, a waveguide for compressional oscillations, and on the other hand, a resonator with opaque boundaries for Alfven waves. The wave transformation is most effective in a resonant case, when the frequency of a compressional mode approaches the local Alfven frequency of a resonator. This model is applied to the interpretation of Pc3 observations in the cusp region. The mechanism can ensure the selective amplification of magnetosheath turbulence in the Pc3 band in the high-latitude cusp.

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Section: Discussionmentioning

confidence: 81%

Magnetohydrodynamic waveguide/resonator for Pc3 ULF pulsations at cusp latitudes

et al. 2014

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“…The additional peak at $ 85 mHz at MGD corresponds to a higher harmonic. The method of extracting resonant eects, which uses the r f ahf ratio (Baransky et al, 1995;Vellante et al, 1993), also stresses the same frequencies (Fig. 3, right panels).…”

Section: A Noisy Sourcementioning

confidence: 71%

“…Reliable interpretation of ground-based data cannot be done by just analyzing spectral features of some wave components only. The physical nature of particular spectral peaks can be revealed with the use of additional information about spatial or polarization structures of ULF signals (Green et al, 1993;Baransky et al, 1995). In this work this approach has been applied to the ULF data from mid-latitude stations along 210°meridian, covering the range v 2X9±1X5 in the Northern and the Southern Hemispheres.…”

Section: Introductionmentioning

confidence: 99%

Hydromagnetic spectroscopy of the magnetosphere with Pc3 geomagnetic pulsations along the 210° meridian

et al. 1999

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Abstract. Analysis of Pc3 observational data along the 210°magnetic meridian showed a complicated frequency-latitude structure at middle latitudes. The observed period-latitude distributions vary between events with à`n oisy source'': the D component has a colored-noise spectrum, while the spectrum of H component exhibits regular peaks that vary with latitude, and events with à`b and-limited source'': the spectral power density of the D component is enhanced at certain frequencies throughout the network. For most ULF events a local gap of the H component amplitude has been exhibited at both conjugate stations at v 9 2X1. A quantitative interpretation has been given assuming that bandlimited MHD emission from an extra-magnetospheric source is distorted by local ®eld line resonances. Resonant frequencies had been singled out with the use of the asymmetry between spectra of H and D components. Additionally, a local resonant frequency at v 9 1X6 was determined by the quasi-gradient method using the data from nearly conjugate stations. The experimentally determined local resonance frequencies agree satisfactorily with those obtained from a numerical model of the Alfven resonator with the equatorial plasma density taken by extrapolation of CarpenterAnderson model. We demonstrate how simple methods of hydromagnetic spectroscopy enable us to monitor simultaneously both the magnitude of the IMF and the magnetospheric plasma density from ULF data.

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“…According to numerous experimental studies of the Pc 3-4 resonant structure (e.g. Baransky et al, 1995) λ x 300 km, hence the inequality λ x < l holds. This consideration may explain the absence of the sunrise effects in our data: the gradient of the ionospheric conductivity is not steep enough to cause a significant distortion of the ground ULF wave structure.…”

Section: Diurnal Variations Of Pc 3 Parametersmentioning

confidence: 99%

“…5(b) and (c)). According to model calculations and special experimental investigations (Baransky et al, 1995;Vellante et al, 1996;Pilipenko et al, 1997) the frequency of the fundamental mode of the Alfvén oscillations at this geomagnetic shell falls within the interval 60-100 mHz. The regularly observed oscillations with lower frequencies in the range 30-60 mHz (LF) are not related to a local field line resonance.…”

Section: Diurnal Variations Of Pc 3 Parametersmentioning

confidence: 99%

Influence of ionospheric conductivity on mid-latitude Pc 3–4 pulsations

et al. 2014

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Diurnal variations of the parameters of the magnetospheric Alfvén resonator at different latitudes have been calculated using a semi-empirical model of the ionosphere-magnetosphere plasma distribution. The ionospheric plasma density is taken from the IRI model, the electron density at the magnetospheric equator is based on the ISEE/whistler model, and the field-aligned magnetospheric plasma distribution is calculated under the assumption of diffusive equilibrium. It is shown that for the mid-latitude ionosphere the Hall conductivity has no effect on the parameters of the magnetospheric Alfvén resonator. The calculated values of damping rates of Alfvén oscillations at middle latitudes during the dark period are too high for the "free-end" and "quarter-wave" oscillation regimes to be realized. At low latitudes quality factors are relatively high both at daytime and nighttime conditions. An expected change of a field-aligned structure of Alfvén oscillations during the transition from dayside to nightside ionospheric conditions does not occur. The analysis of the experimental data recorded at middle and low latitude stations of the "210• Magnetic Meridian" magnetometer network and station l'Aquila gives the results, compatible with the predictions of the numerical model: (a) the pulsation amplitude in a frequency band near the fundamental harmonic of the Alfvén field line resonance has the strongest dependence on the ionospheric conductivity; (b) the influence of day/night ionospheric conditions on the Pc 3 amplitudes is less at low (L ≤ 2) geomagnetic latitudes than at middle latitudes; (c) the ionospheric conductivity control of the Pc 3 amplitude at middle latitudes weakens with increasing harmonic number.

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Gradient and Polarization Methods of Ground-Based Monitoring of Magnetospheric Plasma.

Cited by 18 publications

References 26 publications

Magnetohydrodynamic waveguide/resonator for Pc3 ULF pulsations at cusp latitudes

Magnetohydrodynamic waveguide/resonator for Pc3 ULF pulsations at cusp latitudes

Hydromagnetic spectroscopy of the magnetosphere with Pc3 geomagnetic pulsations along the 210° meridian

Influence of ionospheric conductivity on mid-latitude Pc 3–4 pulsations

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