Propagation of auroral hiss at high altitudes

Santolı́k, O.; Gurnett, D. A.

doi:10.1029/2001gl013666

Cited by 42 publications

(42 citation statements)

References 12 publications

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“…It can be either indicative of a linear polarization or of no polarization. A low coherency value [ Santolik and Gurnett , 2002; Santolik et al , 2002] in Figure 1d indicates that there are random phase shifts between the two components in the polarization plane. The high coherency level of the rising tone is a confirmation of its high degree of polarization.…”

Section: Introductionmentioning

confidence: 99%

Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere

et al. 2010

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[1] We develop a nonlinear wave growth theory of electromagnetic ion cyclotron (EMIC) triggered emissions observed in the inner magnetosphere. We first derive the basic wave equations from Maxwell's equations and the momentum equations for the electrons and ions. We then obtain equations that describe the nonlinear dynamics of resonant protons interacting with an EMIC wave. The frequency sweep rate of the wave plays an important role in forming the resonant current that controls the wave growth. Assuming an optimum condition for the maximum growth rate as an absolute instability at the magnetic equator and a self-sustaining growth condition for the wave propagating from the magnetic equator, we obtain a set of ordinary differential equations that describe the nonlinear evolution of a rising tone emission generated at the magnetic equator. Using the physical parameters inferred from the wave, particle, and magnetic field data measured by the Cluster spacecraft, we determine the dispersion relation for the EMIC waves. Integrating the differential equations numerically, we obtain a solution for the time variation of the amplitude and frequency of a rising tone emission at the equator. Assuming saturation of the wave amplitude, as is found in the observations, we find good agreement between the numerical solutions and the wave spectrum of the EMIC triggered emissions.

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Section: Introductionmentioning

confidence: 99%

Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere

et al. 2010

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“…Whistler turbulence is widely observed not only in the Earth's magnetosphere (Santolik and Gurnett, 2002) but also in planetary plasma environments such as Venus (Scarf et al, 1980), Jupiter (Gurnett et al, 1979), Neptune (Gurnett et al, 1990) and in the solar wind (Lengyel-Frey et al, 1996). At relatively low frequencies, inertial-range turbulence in the solar wind typically exhibits magnetic field fluctuation spectra which scale as frequency to the −5/3 power, but beyond a spectral breakpoint near 0.2-0.5 Hz such spectra become steeper at higher frequencies (Leamon et al, 1998;Sahraoui et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Inertial-range spectrum of whistler turbulence

Narita

Gary

2010

Ann. Geophys.

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Abstract.We develop a theoretical model of an inertialrange energy spectrum for homogeneous whistler turbulence. The theory is a generalization of the Iroshnikov-Kraichnan concept of the inertial-range magnetohydrodynamic turbulence. In the model the dispersion relation is used to derive scaling laws for whistler waves at highly oblique propagation with respect to the mean magnetic field. The model predicts an energy spectrum for such whistler waves with a spectral index −2.5 in the perpendicular component of the wave vector and thus provides an interpretation about recent discoveries of the second inertial-range of magnetic energy spectra at high frequencies in the solar wind.

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“…Gurnett et al (1983) explained this feature by the limitation of ray angles for whistler-mode waves propagating upward with wave vectors close to the resonance cone. This explanation has been experimentally confirmed only recently (Santolík and Gurnett, 2002). Direct measurements of the wave normal and the Poynting flux direction on the POLAR satellite at a radial distance of 5 R E showed that funnel-shaped auroral hiss propagates upward with the Poynting flux directed outward from the auroral oval.…”

Section: Introductionmentioning

confidence: 88%

“…The first hypothesis was confirmed quite recently on the basis of POLAR satellite observations. Using multicomponent wave measurements of the POLAR spacecraft at a radial distance of 5 Earth radii, Santolík and Gurnett (2002) provided the direct evidence that auroral hiss propagated upward and the wave vectors were found close to the whistler mode resonance angle. Our results are also in agreement with the first conclusion of Gurnett et al (1983).…”

Section: Discussionmentioning

confidence: 99%

The relationship between auroral hiss at high altitudes over the polar caps and the substorm dynamics of aurora

et al. 2005

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Abstract. Strong variations of intensity and cutoff frequency of the auroral hiss were observed by INTERBALL-2 and PO-LAR satellites at high altitudes, poleward from the auroral oval. The hiss intensifications are correlated with the auroral activations during substorms and/or pseudo-breakups. The low cutoff frequency of auroral hiss increases with the distance between the aurora and the satellite footprint. Multicomponent wave measurements of the hiss emissions on board the POLAR spacecraft show that the horizontal component of the Poynting flux of auroral hiss changes its direction in good accordance with longitudinal displacements of the bright auroras. The vertical component of the Poynting flux is directed upward from the aurora region, indicating that hiss could be generated by upgoing electron beams. This relationship between hiss and the aurora dynamics means that the upgoing electron beams are closely related to downgoing electron beams which produce the aurora. During the auroral activations the upgoing and downgoing beams move and change their intensities simultaneously.

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Propagation of auroral hiss at high altitudes

Cited by 42 publications

References 12 publications

Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere

Theory and observation of electromagnetic ion cyclotron triggered emissions in the magnetosphere

Inertial-range spectrum of whistler turbulence

The relationship between auroral hiss at high altitudes over the polar caps and the substorm dynamics of aurora

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