A study of concurrent magnetic field and particle precipitation pulsations, 0.005 to 0.5 Hz, recorded near College, Alaska

Heacock, R. R.; Hunsucker, R. D.

doi:10.1016/0021-9169(77)90158-1

Cited by 50 publications

(10 citation statements)

References 34 publications

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“…The precipitation of particles due to whistler mode wave mediated pitch angle scattering is a possible candidate for the self limitation of stably trapped particle fluxes in planetary magnetospheres [ Kennel and Petschek , 1966; Summers et al , 2009]. The modulation of 30 keV–300 keV particle precipitation by ultra low frequency (ULF) waves [ Ziauddin , 1960; Anger et al , 1963; Brown , 1964; Parthasarathy and Hessler , 1964; Hargreaves , 1969; Yuan and Jacka , 1969; Hunsucker et al , 1972; Berkey , 1974; Brown , 1975; Heacock and Hunsucker , 1977; Olson et al , 1980; Paquette et al , 1994; Posch et al , 1999; Spanswick et al , 2005; Rae et al , 2007; Roldugin and Roldugin , 2008] is thought to occur once a steady precipitation rate has been established. Coroniti and Kennel [1970] suggest that this steady precipitation may be accomplished by whistler mode waves.…”

Section: Introductionmentioning

confidence: 99%

Whistler mode wave growth and propagation in the prenoon magnetosphere

Watt¹,

Rankin²,

Degeling³

2012

J. Geophys. Res.

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[1] Pitch angle scattering of electrons can limit the stably trapped particle flux in the magnetosphere and precipitate energetic electrons into the ionosphere. Whistler mode waves generated by a temperature anisotropy can mediate this pitch angle scattering over a wide range of radial distances and latitudes, but in order to correctly predict the phase space diffusion, it is important to characterize the whistler mode wave distributions that result from the instability. We use previously published observations of number density, pitch angle anisotropy, and phase space density to model the plasma in the quiet prenoon magnetosphere (defined as periods when AE < 100 nT). We investigate the global propagation and growth of whistler mode waves by studying millions of growing raypaths and demonstrate that the wave distribution at any one location is a superposition of many waves at different points along their trajectories and with different histories. We show that for observed electron plasma properties, very few raypaths undergo magnetospheric reflection; most rays grow and decay within 30 degrees of the magnetic equator. The frequency range of the wave distribution at large L can be adequately described by the solutions of the local dispersion relation, but the range of wave normal angle is different. The wave distribution is asymmetric with respect to the wave normal angle. The numerical results suggest that it is important to determine the variation of magnetospheric parameters as a function of latitude, as well as local time and L-shell.

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Section: Introductionmentioning

confidence: 99%

Whistler mode wave growth and propagation in the prenoon magnetosphere

Watt¹,

Rankin²,

Degeling³

2012

J. Geophys. Res.

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“…Studies of onset‐related Pi1 pulsations have in general concentrated on a short‐period class of broadband and bursty signals in the ∼0.1–1 Hz frequency range and denoted as Pi1B [e.g., Bösinger , 1989; Lessard et al , 2006]. Pi1B pulsations have been associated with a variety of geophysical phenomena; ionospheric currents, including upward field‐aligned currents [ Bösinger et al , 1981]; enhanced E‐region conductance and electrojet currents [ Heacock and Hunsucker , 1981]; auroral luminosity fluctuations [ Troitskaya , 1961; Arnoldy et al , 1987]; and cosmic noise absorption [ Heacock and Hunsucker , 1977]. These Pi1B pulsations have also recently been identified as localised phenomena associated with substorm onset [e.g., Bösinger and Yahnin , 1987; Arnoldy et al , 1987; Bösinger , 1989].…”

Section: Introductionmentioning

confidence: 99%

Ionospheric localisation and expansion of long‐period Pi1 pulsations at substorm onset

Milling

Rae

Mann

et al. 2008

Geophysical Research Letters

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We examine the initial ionospheric localisation and expansion of Pi1 pulsations associated with a substorm onset observed on 1st November 2006 with the combined CARISMA and THEMIS GMAG network of ground‐based magnetometers. We demonstrate how the first ionospheric pulsation disturbance lies in the long‐period Pi1 band. The long‐period Pi1 pulsations at substorm onset are initially localised in longitude, and expands away from an epicentre in the ionosphere, with ∼16 s timing between stations. We further establish a link between the location of the downward field‐aligned current (FAC) element which subsequently develops within the substorm current wedge (SCW), and the initial location of the onset of long‐period Pi1 pulsations. The arrival of the initial long‐period Pi1 wavepacket demonstrates the importance of global networks of ground‐based magnetometers for probing substorm onset. The Pi1 expansion proceeds westward at a rate of approximately 1 MLT hour per ∼20 seconds, representing a very rapid expansion of the Pi1 signal at the ground. The resolution of the Pi1 localisation and the rate of expansion suggest Pi1 waves can play an important role in studies of the causal sequence of energy release in substorms.

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“…The average SPA effect has a fast rise time and short duration that resemble those of phase change caused by X-ray radiation in the daytime (SWANSON and KUGEL, 1973). Many authors pointed out that ionospheric absorption and bremsstrahlung X-ray effects are closely correlated with the Pi events (e.g., CAMPBELL and MATSUSHITA, 1962;HEACOCK and HUNSUCKER, 1977). We may thus conclude that the SPA'S associated with Pi effects found in our VLF records are also caused by extra ionization due to particle precipitations of pulsating nature or due to the bremsstrahlung X-ray radiation associated with precipitations during Pi events.…”

Section: Sudden Phase Anomalies Associated With Magnetic Pulsationsmentioning

confidence: 58%

Geomagnetic disturbances and associated phase anomalies of a VLF radio wave at midlatitudes.

Hara¹,

Horiai²

1979

J. geomagn. geoelec

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A study of concurrent magnetic field and particle precipitation pulsations, 0.005 to 0.5 Hz, recorded near College, Alaska

Cited by 50 publications

References 34 publications

Whistler mode wave growth and propagation in the prenoon magnetosphere

Whistler mode wave growth and propagation in the prenoon magnetosphere

Ionospheric localisation and expansion of long‐period Pi1 pulsations at substorm onset

Geomagnetic disturbances and associated phase anomalies of a VLF radio wave at midlatitudes.

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