Observations of Ion Cyclotron Waves Near Synchronous Orbit and on the Ground

Fraser, B. J.

doi:10.1007/978-94-009-5454-0_22

Cited by 30 publications

(38 citation statements)

References 42 publications

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“…To estimate the wave normal angle from observations, the minimum variance direction is usually determined by applying Fast Fourier Transform (FFT) decomposition to the data. The extracted is generally less than 30 Fraser, 1985;Ishida et al, 1987]. While highly oblique EMIC waves are observed in the outer magnetosphere [e.g., Anderson et al, 1996aAnderson et al, , 1996bMin et al, 2012] seen in the region of low L shells because both the wave magnetic field (see Figure 3) and group velocity are large there.…”

Section: Wave Normal Angle and Poynting Flux Distributionsmentioning

confidence: 96%

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

et al. 2014

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Citation:Gamayunov, K. V., M. J. Engebretson, M. Zhang, and H. K. Rassoul (2014) Abstract The evolution of He + -mode electromagnetic ion cyclotron (EMIC) waves is studied inside the geostationary orbit using our global model of ring current (RC) ions, electric field, plasmasphere, and EMIC waves. In contrast to the approach previously used by Gamayunov et al. (2009), however, we do not use the bounce-averaged wave kinetic equation but instead use a complete, nonbounce-averaged, equation to model the evolution of EMIC wave power spectral density, including off-equatorial wave dynamics. The major results of our study can be summarized as follows. (1) The thermal background level for EMIC waves is too low to allow waves to grow up to the observable level during one pass between the "bi-ion latitudes" (the latitudes where the given wave frequency is equal to the O + -He + bi-ion frequency) in conjugate hemispheres. As a consequence, quasi-field-aligned EMIC waves are not typically produced in the model if the thermal background level is used, but routinely observed in the Earth's magnetosphere. To overcome this model-observation discrepancy we suggest a nonlinear energy cascade from the lower frequency range of ultralow frequency waves into the frequency range of EMIC wave generation as a possible mechanism supplying the needed level of seed fluctuations that guarantees growth of EMIC waves during one pass through the near equatorial region. The EMIC wave development from a suprathermal background level shows that EMIC waves are quasi field aligned near the equator, while they are oblique at high latitudes, and the Poynting flux is predominantly directed away from the near equatorial source region in agreement with observations. (2) An abundance of O + strongly controls the energy of oblique He + -mode EMIC waves that propagate to the equator after their reflection at bi-ion latitudes, and so it controls a fraction of wave energy in the oblique normals. waves generated by RC O + in the region L ≈ 2-3 may have an implication to the energetic particle loss in the inner radiation belt.

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Section: Wave Normal Angle and Poynting Flux Distributionsmentioning

confidence: 96%

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

et al. 2014

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“…The ion cyclotron instability in the magnetosphere has most commonly been associated with the growth of Pct-2 waves in the dayside equatorial region in the presence of anisotropic and energetic ring current ions (Mauk and McPherron, 1980;Roux et al, 1982;Fraser, 1985). Similarly, in the plasma sheet boundary layer ion distributions are anisotropic and energetic, however they are typically dominated by field-aligned counterstreaming proton beams with energies from 0.5 to >20 keV (Eastman et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Ion Cyclotron Waves Observed in the Near Earth Plasma Sheet Boundary Layer.

Chaston¹,

Hu²,

Fraser³

et al. 1994

J. geomagn. geoelec

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Enhanced magnetic field fluctuations observed during an ISEE-2 crossing of the plasma sheet boundary layer at XGSE = 18.2 Re have the characteristics of electromagnetic ion cyclotron waves. The observed fluctuations propagate essentially along the magnetic field and are left-hand circularly polarized in the spacecraft frame, with frequencies below the proton cyclotron frequency (S2p) and peak power at about 0.2S2p. Plasma data indicate that these waves are associated with decreasing plasma j3 and occur in the presence of an anisotropic earthward directed proton beam with velocity less than the local Alfven speed. Linear Vlasov theory indicates that these waves are most likely excited by the electromagnetic ion cyclotron instability driven by the temperature anisotropy of the proton beam.

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“…According to the statistical studies of satellite observations such as Anderson et al [1992a, b] and Fraser and Nguyen [2001], it is evident that the wave events near the equatorial region have unique features. One property is that wave events with linear polarization are frequently observed [Young et al, 1981;Fraser and McPherron, 1982;Fraser , 1985;Anderson et al, 1992bAnderson et al, , 1996Fraser and Nguyen, 2001]. and Fraser , 1985].…”

Section: R a F T August 26 2008 4:03pm D R A F T X -4 Lee Et Al:mentioning

confidence: 99%

“…One property is that wave events with linear polarization are frequently observed [Young et al, 1981;Fraser and McPherron, 1982;Fraser , 1985;Anderson et al, 1992bAnderson et al, , 1996Fraser and Nguyen, 2001]. and Fraser , 1985]. Because wave surveys involve a wide range of observed frequency relative to the ion cyclotron frequency, it is highly unusual that a significant number of wave events are linearly polarized.…”

Section: R a F T August 26 2008 4:03pm D R A F T X -4 Lee Et Al:mentioning

confidence: 99%

Effects of Heavy Ions on ULF Wave Resonances Near the Equatorial Region

Johnson¹

2008

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Observations of Ion Cyclotron Waves Near Synchronous Orbit and on the Ground

Cited by 30 publications

References 42 publications

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

Model of electromagnetic ion cyclotron waves in the inner magnetosphere

Electromagnetic Ion Cyclotron Waves Observed in the Near Earth Plasma Sheet Boundary Layer.

Effects of Heavy Ions on ULF Wave Resonances Near the Equatorial Region

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