Global compressional oscillations of the terrestrial magnetosphere: The evidence and a model

Kivelson, M. G.; Etcheto, J.; Trotignon, J. G.

doi:10.1029/ja089ia11p09851

Cited by 187 publications

(135 citation statements)

References 13 publications

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“…In some cases, a nonlinear effect, known as the feedback instability, takes place (Lysak and Song, 2002;Streltsov and Foster, 2004;Foster et al, 2004). Some of these Alfvén waves are mode-converted from fast mode waves which have their origin in the solar wind or at the magnetopause (Southwood, 1974;Chen and Hasegawa, 1974;Kivelson et al, 1984). As another possibility, the observed electromagnetic fluctuations are not waves, but the magnetospheric counterpart of static ionospheric currents (Gurnett et al, 1984;Dombeck et al, 2005) as studied in the auroral region.…”

Section: Introductionmentioning

confidence: 99%

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

et al. 2012

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Abstract. In this event study, small-scale fluctuations in plasmaspheric plumes with time scales of ∼10 s to minutes in the spacecraft frame are examined. In one event, plasmaspheric plumes are observed by Cluster, while IMAGE measured density enhancement at a similar location. Fluctuations in density exist in plumes as detected by Cluster and are accompanied by fluctuations in magnetic fields and electric fields. Magnetic fluctuations are transverse and along the direction of the plumes. The E/B ratio is smaller than the Alfvén velocity. Another similar event is briefly presented. We then consider physical properties of the fluctuations. Alfvén mode modulated by the feedback instability is one possibility, although non-local generation is likely. It is hard to show that the fluctuations represent a fast mode. Interchange motion is possible due to the consistency between measurements and expectations. The energy source could be a pressure or density gradient in plasmaspheric plumes. When more events are accumulated so that statistical analysis becomes feasible, this type of study will be useful to understand the time evolution of plumes.

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Section: Introductionmentioning

confidence: 99%

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

et al. 2012

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“…Later modifications in the drift mirror mode have been introduced, taking into account magnetic field curvature and coupling to compressional and shear Alfvén waves Hasegawa, 1991, 1994;Cheng and Qian, 1994). There are also suggestions that compressional pulsations can be global modes of the magnetosphere (Kivelson et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

Compressional Pc5 type pulsations in the morningside plasma sheet

et al. 2001

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Abstract. We study compressional pulsations in Pc5 frequency range observed in the dawn-side at distances of about 10 R E , close to the magnetic equator. We use data obtained during two events of conjunctions between Equator-S and Geotail: 1000-1700 UT on 9 March 1998, and 0200-0600 UT on 25 April 1998. In both events, pulsations are observed after substorm activity. The pulsations are antisymmetric with respect to the equatorial plane (even mode), and move eastward with phase velocity close to plasma velocity. The pulsations tend to be pressure balanced. We also discuss possible generation mechanisms of the pulsations.

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“…A similar plasma density has been inferred before (e.g. Singer et al, 1979;Kivelson et al, 1984) and is likely to represent a particle density of~10 cm )3 with an effective ion mass of mi ∼ 7 mp (proton masses), caused by the the presence of O + and He + in the plasmatrough. In order to produce a reasonable correlation with the Goose Bay data, an equatorial plasma density equivalent to 38 protons cm )3 at L 6 was required.…”

Section: Observationsmentioning

confidence: 54%

A comparison of field-line resonances observed at the Goose Bay and Wick radars

Provan

Yeoman

1997

Ann. Geophys.

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Abstract. Previous observations with the Goose Bay HF coherent-scatter radar have revealed structured spectral peaks at ultra-low frequencies. The frequencies of these spectral peaks have been demonstrated to be extremely consistent from day to day. The stability of these spectral peaks can be seen as evidence for the existence of global magnetospheric cavity modes whose resonant frequencies are independent of latitude. Fieldline resonances occur when successive harmonics of the eigenfrequency of the magnetospheric cavity or waveguide match either the first harmonic eigenfrequency of the geomagnetic field lines or higher harmonics of this frequency. Power spectra observed at the SABRE VHF coherent-scatter radar at Wick, Scotland, during night and early morning are revealed to show similarly clearly structured spectral peaks. These spectral peaks are the result of local field-line resonances due to Alfvén waves standing on magnetospheric field lines. A comparison of the spectra observed by the Goose Bay and Wick radars demonstrate that the frequencies of the field-line resonances are, on average, almost identical, despite the different latitudinal ranges covered by the two radars. Possible explanations for the similarity of the signatures on the two radar systems are discussed.

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Global compressional oscillations of the terrestrial magnetosphere: The evidence and a model

Cited by 187 publications

References 13 publications

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Multi-spacecraft observations of small-scale fluctuations in density and fields in plasmaspheric plumes

Compressional Pc5 type pulsations in the morningside plasma sheet

A comparison of field-line resonances observed at the Goose Bay and Wick radars

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