Hydromagnetic wave coupling in the magnetosphere—Plasmapause effects on impulse-excited resonances

Allan, W.; Poulter, E. M.; White, Sarahlouise

doi:10.1016/0032-0633(86)90056-5

Cited by 137 publications

(95 citation statements)

References 16 publications

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“…solar wind impulses (Allan et al, 1986) and Kelvin-Helmholtz instabilities at the magnetopause (Fujita et al, 1996;Engebretson et al, 1998) generating a compressional wave which propagates across magnetic field lines. Due to the process known as field line resonance (Tamao, 1965;Southwood, 1974), the compressional wave can be transformed to an Alfvén wave propagating parallel to the magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause

et al. 2008

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Abstract.A case study of a poloidal ULF pulsation near the dayside plasmapause is presented based on Cluster observations of magnetic and electric fields. The pulsation is detected close to the magnetic equatorial plane at L shells L=[4.4, 4.6] and oscillates with a frequency of f =23 mHz. Investigating the wave energy flux reveals the standing wave nature of the observed pulsation. An estimation of the azimuthal wave number exposes a narrow azimuthal structure of the wave field with m≈160. Spatial and temporal characteristics of the pulsation are analyzed in detail by representing data in a field line related coordinate system and a rangetime-intensity representation. This allows an estimation of both the spatial extension of the wave field in the radial direction and its temporal decay rate. The analysis furthermore indicates that the same field lines are excited to a standing wave oscillation twice. Furthermore an accurate identification of a phase jump of the wave field across L shells is possible. Comparing the radial localization of the detected wave with theoretically expected field line eigenfrequencies reveals that the wave field is confined in the Alfvén resonator at the outer edge of the plasmapause.

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Section: Introductionmentioning

confidence: 99%

Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause

et al. 2008

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“…Responding these observational facts, there are several theoretical works studying MHD response of the magnetosphere from an impulsive source [Allan, 1986;Lee, 1996Lee, , 1998 model (referred to as the source current). This is the first work that considers explicitly the relation between the current wedge and the Pi2 pulsation.…”

Section: Introductionmentioning

confidence: 99%

Propagation property of transient MHD impulses in the Magnetosphere‐Ionosphere System: The 2D model of the Pi2 pulsation

Fujita

Mizuta²,

Itonaga

et al. 2001

Geophysical Research Letters

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Abstract.Propagation property of the 2D-coupled MHD wave induced from an impulsive current is studied by using a magnetospheric model having the dipole magnetic field, the ionosphere with Pedersen conductivity, and a free outer boundary. This study is the first step toward realistic modeling of Pi2 pulsation generated by the current wedge model. Numerical calculation reveals that the ionosphere controls not only damping of the field-line resonance oscillation but also its frequency. The field-line resonance oscillation exhibits the fundamental mode structure along the field line in the plasmasphere. In high latitudes, there are waves bouncing between the ionospheres. This suggests that the waveform in the middle-and low-latitudes is different

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“…The 36 mHz peak, which is most likely related to UW activity, showed a similar structure at the ground stations; however, the corresponding peaks in CHAMP components are not significant. The observed features of these two components correspond to the FMR modelled by Allan et al (1986a) with a node on the plasmapause. We also note that for this event the plasmapause seems to influence the spatial structure of other frequency components.…”

Section: Conclusion and Discussionmentioning

confidence: 64%

“…Energy from the compressional wave-guide modes can also tunnel to field lines earthward of the turning point to drive discrete shear Alfvén mode resonances where their eigenfrequencies match those of the fast modes (Samson et al, 1995). Some of the earlier models were those of Kivelson and Southwood (1985), who used a simple box model of the magnetosphere, Allan et al (1985Allan et al ( , 1986a, who used an infinitely long half-cylinder magnetosphere model, while Samson et al (1995) used a WKB (Wentzel-Kramers-Brillouin) analysis of a wave-guide mode to show that damped, fast eigenmode solutions with quantized frequency are produced. The model of Allan et al (1986b) showed that the compressional component periods are virtually constant over the whole range of radial distance, which they interpreted as standing-wave harmonics in the magnetospheric cavity.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…The signals in the B tor component of our dynamic spectra with quasi-constant frequency as CHAMP rapidly moves across L shells may be evidence of this monochromatic transverse component. Allan et al (1986a) plays a pivotal role in determining which compressional cavity resonances are dominant. The critical factor is whether a node of a particular cavity resonance lies on or near the plasmapause, in which case the resonance is enhanced; otherwise, it is attenuated.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Spectral structure of Pc3–4 pulsations: possible signatures of cavity modes

Sutcliffe

Heilig²,

Lotz³

2013

Ann. Geophys.

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In this study we investigate the spectral structure of Pc3–4 pulsations observed at low and midlatitudes. For this purpose, ground-based magnetometer data recorded at the MM100 stations in Europe and at two low latitude stations in South Africa were used. In addition, fluxgate magnetometer data from the CHAMP (CHAllenging Minisatellite Payload) low Earth orbit satellite were used. The results of our analysis suggest that at least three mechanisms contribute to the spectral content of Pc3–4 pulsations typically observed at these latitudes. We confirm that a typical Pc3–4 pulsation contains a field line resonance (FLR) contribution, with latitude dependent frequency, and an upstream wave (UW) contribution, with frequency proportional to the IMF (interplanetary magnetic field) magnitude B_IMF. Besides the FLR and UW contributions, the Pc3–4 pulsations consistently contain signals at other frequencies that are independent of latitude and B_IMF. We suggest that the most likely explanation for these additional frequency contributions is that they are fast mode resonances (FMRs) related to cavity, waveguide, or virtual modes. Although the above contributions to the pulsation spectral structure have been reported previously, we believe that this is the first time where evidence is presented showing that they are all present simultaneously in both ground-based and satellite data

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Hydromagnetic wave coupling in the magnetosphere—Plasmapause effects on impulse-excited resonances

Cited by 137 publications

References 16 publications

Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause

Spatio-temporal structure of a poloidal Alfvén wave detected by Cluster adjacent to the dayside plasmapause

Propagation property of transient MHD impulses in the Magnetosphere‐Ionosphere System: The 2D model of the Pi2 pulsation

Spectral structure of Pc3–4 pulsations: possible signatures of cavity modes

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