Substorm dependence of chorus amplitudes: Implications for the acceleration of electrons to relativistic energies

Meredith, Nigel P.; Horne, Richard B.; Anderson, R. R.

doi:10.1029/2000ja900156

Cited by 481 publications

(696 citation statements)

References 29 publications

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“…There are discrepancies of the required wave amplitudes between 50 and 100 eV/nT (less than a factor of 2), and some of these discrepancies are due to the ambiguity of the assumed wave normal angle and the plasma parameters. The mean value of the required wave amplitudes at 50 and 100 eV/nT electrons are 7.48, 9.06, 12.0, 13.7, and 14.9 pT for Kp = 0, 1, 2, 3, and 4, respectively, while the observed average wave amplitudes of the chorus waves are a few pT during quiet conditions and enhanced during active conditions with amplitudes of^10 pT [Meredith et al, 2001]. Therefore, the required wave amplitudes are roughly consistent with the observed average amplitudes of the chorus waves.…”

Section: Electron Loss Time Scalementioning

confidence: 98%

“…The chorus waves are frequently observed from the nightside through dawn to the dayside equatorial magnetosphere [e.g., Meredith et al, 2001;Li et al, 2009]. Therefore, the chorus wave is a primary candidate that interacts with plasma sheet electrons in the morning sector and causes them to precipitate into the atmosphere.…”

Section: Evaluation Of Theoretical Loss Time Scales Based On Pitch Anmentioning

confidence: 99%

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Transport and loss of the inner plasma sheet electrons: THEMIS observations

et al. 2011

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[1] Using the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements from 2007 to 2009, we derived global phase space density (PSD) distributions of plasma sheet electrons (2-100 eV/nT) to examine the transport process of the electrons to the inner magnetosphere and possible loss mechanisms of plasma sheet electrons during the convective transport. The inner boundaries of the electron plasma sheet were determined by the observed global distributions and compared with the Alfvén boundaries that were calculated by the sum of the simple corotation and convection electric field models. This comparison confirms the previous results that the large-scale convection electric field controls the electron transport to the inner magnetosphere. The gradual decrease in PSD is observed from the dawn to the dayside sector, indicating the existence of some loss mechanisms in the morning sector. The loss time scales estimated from the PSD distributions were compared with the theoretical ones based on the quasi-linear diffusion theory using an empirical wave model of whistler mode chorus. We also estimated the required wave amplitudes that can explain the estimated loss time scales. It is shown that whistler mode chorus has a sufficient power to scatter the plasma sheet electrons, and the required wave amplitudes are roughly consistent with the CRRES statistical survey of the chorus wave amplitude. We suggest that the loss of plasma sheet electrons in the morning sector is mainly induced by pitch angle scattering by whistler mode chorus.

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Section: Electron Loss Time Scalementioning

confidence: 98%

Section: Evaluation Of Theoretical Loss Time Scales Based On Pitch Anmentioning

confidence: 99%

Transport and loss of the inner plasma sheet electrons: THEMIS observations

et al. 2011

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“…[17] Whistler-mode chorus waves, which are observed in the low-density region outside of the plasmapause, can fall into the frequency range between 0.1 and 5 kHz [e.g., Meredith et al, 2001]. In order to exclude these emissions from the study we adopt a criterion based on the amplitude of the waves in the band f ce < f < 2f ce .…”

Section: Identification Of Plasmaspheric Hiss and Lightning Generatedmentioning

confidence: 99%

Slot region electron loss timescales due to plasmaspheric hiss and lightning‐generated whistlers

et al. 2007

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[1] Energetic electrons (E > 100 keV) in the Earth's radiation belts undergo Dopplershifted cyclotron resonant interactions with a variety of whistler mode waves leading to pitch angle scattering and subsequent loss to the atmosphere. In this study we assess the relative importance of plasmaspheric hiss and lightning-generated whistlers in the slot region and beyond. Electron loss timescales are determined using the Pitch Angle and energy Diffusion of Ions and Electrons (PADIE) code with global models of the spectral distributions of the wave power based on CRRES observations. Our results show that plasmaspheric hiss propagating at small and intermediate wave normal angles is a significant scattering agent in the slot region and beyond. In contrast, plasmaspheric hiss propagating at large wave normal angles and lightning-generated whistlers do not contribute significantly to radiation belt loss. The loss timescale of 2 MeV electrons due to plasmaspheric hiss propagating at small and intermediate wave normal angles in the center of the slot region (L = 2.5) lies in the range 1-10 days, consistent with recent Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) observations. Wave turbulence in space, which is responsible for the generation plasmaspheric hiss, thus leads to the formation of the slot region. During active periods, losses due to plasmaspheric hiss may occur on a timescale of 1 day or less for a wide range of energies, 200 keV < E < 1 MeV, in the region 3.5 < L < 4.0. Plasmaspheric hiss may thus also be a significant loss process in the inner region of the outer radiation belt during magnetically disturbed periods.Citation: Meredith, N. P., R. B. Horne, S. A. Glauert, and R. R. Anderson (2007), Slot region electron loss timescales due to plasmaspheric hiss and lightning-generated whistlers,

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“…The pitch-angle scattering of the radiation belt energetic electrons by chorus can lead to significant precipitation into the atmosphere [Lorentzen et al, 2001;Meredith et al, 2001;Summers, 2005]. Tsurutani and Smith [1974] and Anderson and Maeda [1977] found that the onset of the chorus emissions coincided with the injection of substorm electrons with energies of ∼10-100 keV.…”

Section: Introductionmentioning

confidence: 99%

Pc5 geomagnetic pulsations, pulsating particle precipitation, and VLF chorus: Case study on 24 November 2006

Manninen¹,

Клейменова

Козырева

et al. 2010

J. Geophys. Res.

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[1] The event (24 November 2006, ∼0400-0500 UT) of the simultaneous observations of Pc5 ULF geomagnetic pulsations, electron precipitation (CNA riometer absorption), and whistler-mode chorus, as well as solar wind (SW) and IMF parameters have been analyzed based on the data from IMAGE magnetometers, Finnish riometer array, and temporal VLF station. The visible correlation between the simultaneous occurrence of several minutes scale patches of chorus and pulsating CNA enhancements was found. The dynamic spectra of the riometer data showed a maximum at ∼3.5 mHz in the first half-hour interval and at ∼2.0 mHz in the second one, while the ULF pulsation spectra exhibit these two maxima in both intervals simultaneously. In the first time interval, the Pc5 pulsations at ∼3.5 mHz demonstrated the typical FLR feature. The SW dynamic pressure fluctuations showed a broad (1.5-3.5 mHz) spectral maximum in the first interval; however, in the second one, the simultaneous oscillations at ∼2.0 mHz were observed in SW pressure and in IMF Bz. The similar ∼2.0 mHz peak has been found in the spectra of Pc5 pulsations from auroral zone to the equator, in riometer absorption, and in VLF chorus power. We suggest that the modulation of particle precipitation and whistler-mode chorus patches was caused by the 2.0 mHz compressional component of Pc5 poloidal geomagnetic pulsations driven in the magnetosphere by SW dynamic pressure and IMF Bz disturbances.

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Substorm dependence of chorus amplitudes: Implications for the acceleration of electrons to relativistic energies

Cited by 481 publications

References 29 publications

Transport and loss of the inner plasma sheet electrons: THEMIS observations

Transport and loss of the inner plasma sheet electrons: THEMIS observations

Slot region electron loss timescales due to plasmaspheric hiss and lightning‐generated whistlers

Pc5 geomagnetic pulsations, pulsating particle precipitation, and VLF chorus: Case study on 24 November 2006

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