Polarisation and propagation of lion roars in the dusk side magnetosheath

Maksimović, M.; Harvey, C. C.; Santolı́k, O.; Lacombe, Catherine; Conchy, Y. de; Hubert, D.; Pantellini, Filippo; Cornilleau-Werhlin, N.; Dandouras, I.; Lucek, E.; Balogh, A.

doi:10.5194/angeo-19-1429-2001

Cited by 38 publications

(79 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The red curves depict the growth rate of waves excited by the electron temperature anisotropy. The maximum of the phase speed shifts to ω∼0.2 e , which is in a reasonable agreement with the magnetosheath observations (Zhang et al, 1988;Baumjohann et al, 1999;Maksimovic et al, 2001). Note that, in general, this frequency does not coincide with the frequency at which the growth rate reaches the maximum value.…”

Section: Modifications Due To a Finite Electron Temperaturesupporting

confidence: 78%

“…Note that if a characteristic scale of magnetic bottles along the magnetic field is about 10 4 km (see e.g. Maksimovic et al, 2001) then the transit time of whistler waves at ω∼0.1 e is about 5 s, and dur- ing 0.5-1 min of a wave activity, the wave packets can either propagate across several successive magnetic bottles or be trapped in a magnetic field trough.…”

Section: Multipoint Measurementsmentioning

confidence: 99%

“…STAFF (Spatio-Temporal Analysis of Field Fluctuations) comprises of a triaxial search coil magnetometer, a waveform receiver (SC) with an upper frequency of either 10 Hz or 180 Hz, and a digital spectrum analyzer (SA) with a frequency range up to 4 kHz (Cornilleau-Wehrlin et al, 1997Maksimovic et al, 2001). In this study we use the data acquired in the burst mode of STAFF operation when the wave form of whistler emissions can be recovered up to a frequency of 180 Hz.…”

Section: Instrumentationmentioning

confidence: 99%

See 2 more Smart Citations

Coherent whistler emissions in the magnetosphere – Cluster observations

et al. 2007

Self Cite

View full text Add to dashboard Cite

Abstract. The STAFF-SC observations complemented by the data from other instruments on Cluster spacecraft were used to study the main properties of magnetospheric lion roars: sporadic bursts of whistler emissions at f ∼0.1−0.2f e where f e is the electron gyrofrequency. Magnetospheric lion roars are shown to be similar to the emissions in the magnetosheath while the conditions for their generation are much less favorable: the growth rate of the cyclotron temperature anisotropy instability is much smaller due to a smaller number of the resonant electrons. This implies a nonlinear mechanism of generation of the observed wave emissions. It is shown that the observed whistler turbulence, in reality, consists of many nearly monochromatic wave packets. It is suggested that these structures are nonlinear Gendrin's whistler solitary waves. Properties of these waves are widely discussed. Since the group velocity of Gendrin's waves is aligned with the magnetic field, these well guided wave packets can propagate through many magnetic "bottles" associated with mirror structures, without being trapped.

show abstract

Section: Modifications Due To a Finite Electron Temperaturesupporting

confidence: 78%

Section: Multipoint Measurementsmentioning

confidence: 99%

Section: Instrumentationmentioning

confidence: 99%

See 1 more Smart Citation

Coherent whistler emissions in the magnetosphere – Cluster observations

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…We now know that part of the BEN, at least some of the higher frequency part extending up to as much as 40-60 kHz, which is also near or higher than the typical electron plasma frequency in the magnetosheath, is a result of the isolated solitary waves imbedded in the wave field as detailed in Pickett et al (2003). The remainder of the wave electric field usually consists of waves with frequencies around 1-3 kHz, the mode identification of which has still not been made, as well as short bursts of lion roars around a few Hundred Hz (also clearly seen in the wave magnetic field data) (Tsurutani et al, 1982;Maksimovic et al, 2001) and electron cyclotron waves around the local electron cyclotron frequency.…”

Section: Introductionmentioning

confidence: 99%

On the generation of solitary waves observed by Cluster in the near-Earth magnetosheath

Pickett

Chen

Kahler

et al. 2005

Nonlin. Processes Geophys.

Self Cite

View full text Add to dashboard Cite

Abstract. Through case studies involving Cluster waveform observations, solitary waves in the form of bipolar and tripolar pulses have recently been found to be quite abundant in the near-Earth dayside magnetosheath. We expand on the results of those previous studies by examining the distribution of solitary waves from the bow shock to the magnetopause using Cluster waveform data. Cluster's orbit allows for the measurement of solitary waves in the magnetosheath from about 10 R E to 19.5 R E . Our results clearly show that within the magnetosheath, solitary waves are likely to be observed at any distance from the bow shock and that this distance has no dependence on the time durations and amplitudes of the solitary waves. In addition we have found that these same two quantities show no dependence on either the ion velocity or the angle between the ion velocity and the local magnetic field direction. These results point to the conclusion that the solitary waves are probably created locally in the magnetosheath at multiple locations, and that the generation mechanism is most likely not solely related to ion dynamics, if at all. To gain insight into a possible local generation mechanism, we have examined the electron differential energy flux characteristics parallel and perpendicular to the magnetic field, as well as the local electron plasma and cyCorrespondence to: J. S. Pickett (pickett@uiowa.edu) clotron frequencies and the type of bow shock that Cluster is behind, for several time intervals where solitary waves were observed in the magnetosheath. We have found that solitary waves are most likely to be observed when there are counterstreaming (∼ parallel and anti-parallel to the magnetic field) electrons at or below about 100 eV. However, there are times when these counterstreaming electrons are present when solitary waves are not. During these times the background magnetic field strength is usually very low (<10 nT), implying that the amplitudes of the solitary waves, if present, would be near or below those of other waves and electrostatic fluctuations in this region making it impossible to isolate or clearly distinguish them from these other emissions in the waveform data. Based on these results, we have concluded that some of the near-Earth magnetosheath solitary waves, perhaps in the form of electron phase-space holes, may be generated locally by a two-stream instability involving electrons based on the counterstreaming electrons that are often observed when solitary waves are present. We have not ruled out the possibility that the solitary waves could be generated as a result of the lower-hybrid Buneman instability in the presence of an electron beam, through the electron acoustic mode or through processes involving turbulence, which is almost always present in the magnetosheath, but these will be examined in a more comprehensive study in the future.

show abstract

“…from regions close to the magnetopause, in the outer cusp or in association with the bowshock by, e.g., Smith et al (1967) (OGO-1); Olson et al (1969) (OGO-3); Rodriguez and Gurnett (1975) ; Tsurutani and Smith (1977) (OGO-5); Gurnett et al, 1979 (ISEE 1 and 2); LaBelle and Treumann (1988) (AMPTE/IRM); Zhang et al (1998) (Geotail); Pickett et al (1999) (Polar) and Maksimovic et al (2001) (Cluster).…”

Section: Introductionmentioning

confidence: 99%

Internal structure and spatial dimensions of whistler wave regions in the magnetopause boundary layer

et al. 2007

View full text Add to dashboard Cite

Abstract. We use whistler waves observed close to the magnetopause as an instrument to investigate the internal structure of the magnetopause-magnetosheath boundary layer. We find that this region is characterized by tube-like structures with dimensions less than or comparable with an ion inertial length in the direction perpendicular to the ambient magnetic field. The tubes are revealed as they constitute regions where whistler waves are generated and propagate. We believe that the region containing tube-like structures extend several Earth radii along the magnetopause in the boundary layer. Within the presumed wave generating regions we find current structures moving at the whistler wave group velocity in the same direction as the waves.

show abstract

Polarisation and propagation of lion roars in the dusk side magnetosheath

Cited by 38 publications

References 24 publications

Coherent whistler emissions in the magnetosphere – Cluster observations

Coherent whistler emissions in the magnetosphere – Cluster observations

On the generation of solitary waves observed by Cluster in the near-Earth magnetosheath

Internal structure and spatial dimensions of whistler wave regions in the magnetopause boundary layer

Contact Info

Product

Resources

About