Magnetic field turbulence, electron heating, magnetic holes, proton cyclotron waves, and the onsets of bipolar pulse (electron hole) events: a possible unifying scenario

Tsurutani, B. T.; Dasgupta, B.; Arballo, J. K.; Lakhina, G. S.; Pickett, J. S.

doi:10.5194/npg-10-27-2003

Cited by 33 publications

(42 citation statements)

References 31 publications

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“…Their results present a consistent picture that associates cold electron beams with solitary waves in the auroral acceleration region (Ergun et al, 1998b). Tsurutani et al (2003) proposed that the parallel electric field component of obliquely propagating electromagnetic proton cyclotron waves can provide a mechanism for short duration bi-directional heated electron beams which then produce the bipolar pulses. The proton cyclotron waves arise through the loss cone instability as a result of an anisotropy in the particles caused by greater heating of the electrons than ions by phase-steepened Alfvén waves.…”

Section: Discussionsupporting

confidence: 61%

“…However, these electron beams are not always present at the exact times when the solitary waves are observed on Cluster, perhaps because the time resolution of the Cluster PEACE instrument is not sufficient when compared to solitary waves that occur on time scales on the order of 1 ms. Further, the PEACE angular resolution is not narrow enough to determine whether the beams that are occasionally observed simultaneously with the solitary waves are actually beams, or whether they are unresolved conics. We also point out that electron beams were not observed at the time of two bipolar pulse onset events in a study carried out by Tsurutani et al (2003) using Polar data. The electron data used by Tsurutani et al (2003) were also of much lower time resolution than the time scales of the pulses.…”

Section: Discussionmentioning

confidence: 99%

“…We also point out that electron beams were not observed at the time of two bipolar pulse onset events in a study carried out by Tsurutani et al (2003) using Polar data. The electron data used by Tsurutani et al (2003) were also of much lower time resolution than the time scales of the pulses. FAST is the only spacecraft thus far that has the time resolution necessary to correlate solitary waves and electrons.…”

Section: Discussionmentioning

confidence: 99%

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Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective

Pickett

Kahler

Chen

et al. 2004

Nonlin. Processes Geophys.

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Abstract. We report on recent measurements of solitary waves made by the Wideband Plasma Wave Receiver located on each of the four Cluster spacecraft at 4.5-6.5 R E (well above the auroral acceleration region) as they cross field lines that map to the auroral zones. These solitary waves are observed in the Wideband data as isolated bipolar and tripolar waveforms. Examples of the two types of pulses are provided. The time durations of the majority of both types of solitary waves observed in this region range from about 0.3 up to 5 ms. Their peak-to-peak amplitudes range from about 0.05 up to 20 mV/m, with a few reaching up to almost 70 mV/m. There is essentially no potential change across the bipolar pulses. There appears to be a small, measurable potential change, up to 0.5 V, across the tripolar pulses, which is consistent with weak or hybrid double layers. A limited cross-spacecraft correlation study was carried out in order to identify the same solitary wave on more than one spacecraft. We found no convincing correlations of the bipolar solitary waves. In the two cases of possible correlation of the tripolar pulses, we found that the solitary waves are propagating at several hundred to a few thousand km/s and that they are possibly evolving (growing, decaying) as they propagate from one spacecraft to the next. Further, they have a perpendicular (to the magnetic field) width of 50 km or greater and a parallel width of about 2-5 km. We conclude, in general, Correspondence to: J. S. Pickett (pickett@uiowa.edu) however, that the Cluster spacecraft at separations along and perpendicular to the local magnetic field direction of tens of km and greater are too large to obtain positive correlations in this region. Looking at the macroscale of the auroral zone at 4.5-6.5 R E , we find that the onsets of the broadband electrostatic noise associated with the solitary waves observed in the spectrograms of the WBD data are generally consistent with propagation of the solitary waves up the field lines (away from Earth), or with particles or waves propagating up the field line, which leads to local generation of the solitary waves all along the field lines. A discussion of the importance of these solitary waves in magnetospheric processes and their possible generation mechanisms, through electron beam instabilities and turbulence, is provided.

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Section: Discussionsupporting

confidence: 61%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective

Pickett

Kahler

Chen

et al. 2004

Nonlin. Processes Geophys.

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“…From the analysis of three component magnetic field and plasma data from Polar, Tsurutani et al (2003) identified two magnetic hole events which occurred on 20 May 1996 during the interval 08:25:17.2 to 08:26:06.4 UT and 08:26:39.8 to 08:27:28.9 UT, respectively. The Polar satellite happens to be in the polar cap/polar cusp boundary layer at these times.…”

Section: Alfvén Wavesmentioning

confidence: 99%

“…Recently, Tsurutani et al (2003) have examined two magnetic hole events in detail using a full complement of Polar field and plasma data on 20 May 1996 when Polar was in the polar cap/polar cusp boundary layer. They found isotropic electron heating, accompanied by nonlinear Alfvén waves, large amplitude (±14 nT peak-to-peak) obliquely propagating proton cyclotron waves (with frequency f ∼0.6 to 0.7 f cp ), and electric bipolar pulses (electron holes), located within magnetic holes/cavities/bubbles.…”

Section: Introductionmentioning

confidence: 99%

Association of Alfvén waves and proton cyclotron waves with electrostatic bipolar pulses: magnetic hole events observed by Polar

Lakhina

Tsurutani

Pickett

2004

Nonlin. Processes Geophys.

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Abstract. Two magnetic hole events observed by Polar on 20 May 1996 when it was in the polar cap/polar cusp boundary layer are studied. Low-frequency waves, consisting of nonlinear Alfvén waves and large amplitude (±14 nT peakto-peak) obliquely propagating proton cyclotron waves (with frequency f ∼0.6 to 0.7f cp ), accompanied by electric bipolar pulses (electron holes) and electron heating have been observed located within magnetic holes. It is shown that lowfrequency waves can provide free energy to drive some high frequency instabilities which saturate by trapping electrons, thus, leading to the generation of electron holes.

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Extremely intense ELF magnetosonic waves: A survey of polar observations

et al. 2014

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A Polar magnetosonic wave (MSW) study was conducted using 1 year of 1996-1997 data (during solar minimum). Waves at and inside the plasmasphere were detected at all local times with a slight preference for occurrence in the midnight-postmidnight sector. Wave occurrence (and intensities) peaked within~±5°of the magnetic equator, with half maxima at~±10°. However, MSWs were also detected as far from the equator as +20°and 60°MLAT but with lower intensities. An extreme MSW intensity event of amplitude B w =~± 1 nT and E w =~± 25 mV/m was detected. This event occurred near local midnight, at the plasmapause, at the magnetic equator, during an intense substorm event, e.g., a perfect occurrence. These results support the idea of generation by protons injected from the plasma sheet into the midnight sector magnetosphere by substorm electric fields. MSWs were also detected near noon (1259 MLT) during relative geomagnetic quiet (low AE). A possible generation mechanism is a recovering/expanding plasmasphere engulfing preexisting energetic ions, in turn leading to ion instability. The wave magnetic field components are aligned along the ambient magnetic field direction, with the wave electric components orthogonal, indicating linear wave polarization. The MSW amplitudes decreased at locations further from the magnetic equator, while transverse whistler mode wave amplitudes (hiss) increased. We argue that intense MSWs are always present somewhere in the magnetosphere during strong substorm/convection events. We thus suggest that modelers use dynamic particle tracing codes and the maximum (rather than average) wave amplitudes to simulate wave-particle interactions.

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Magnetic field turbulence, electron heating, magnetic holes, proton cyclotron waves, and the onsets of bipolar pulse (electron hole) events: a possible unifying scenario

Cited by 33 publications

References 31 publications

Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective

Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective

Association of Alfvén waves and proton cyclotron waves with electrostatic bipolar pulses: magnetic hole events observed by Polar

Extremely intense ELF magnetosonic waves: A survey of polar observations

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