scholarly journals Resonant scattering of plasma sheet electrons leading to diffuse auroral precipitation: 2. Evaluation for whistler mode chorus waves

2011 ◽  
Vol 116 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Binbin Ni ◽  
Richard M. Thorne ◽  
Nigel P. Meredith ◽  
Richard B. Horne ◽  
Yuri Y. Shprits
Keyword(s):  
Plasma Sheet ◽  
Resonant Scattering ◽  
Whistler Mode ◽  
Chorus Waves

scholarly journals Evolution of the plasma sheet electron pitch angle distribution by whistler-mode chorus waves in non-dipole magnetic fields

2012 ◽  
Vol 30 (4) ◽  
pp. 751-760 ◽  
Author(s):  
Q. Ma ◽  
B. Ni ◽  
X. Tao ◽  
R. M. Thorne
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Diffusion Equation ◽  
Plasma Sheet ◽  
Diffusion Coefficients ◽  
Electron Distribution ◽  
Dipole Field ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Fokker Planck

Abstract. We present a detailed numerical study on the effects of a non-dipole magnetic field on the Earth's plasma sheet electron distribution and its implication for diffuse auroral precipitation. Use of the modified bounce-averaged Fokker-Planck equation developed in the companion paper by Ni et al. (2012) for 2-D non-dipole magnetic fields suggests that we can adopt a numerical scheme similar to that used for a dipole field, but should evaluate bounce-averaged diffusion coefficients and bounce period related terms in non-dipole magnetic fields. Focusing on nightside whistler-mode chorus waves at L = 6, and using various Dungey magnetic models, we calculate and compare of the bounce-averaged diffusion coefficients in each case. Using the Alternative Direction Implicit (ADI) scheme to numerically solve the 2-D Fokker-Planck diffusion equation, we demonstrate that chorus driven resonant scattering causes plasma sheet electrons to be scattered much faster into loss cone in a non-dipole field than a dipole. The electrons subject to such scattering extends to lower energies and higher equatorial pitch angles when the southward interplanetary magnetic field (IMF) increases in the Dungey magnetic model. Furthermore, we find that changes in the diffusion coefficients are the dominant factor responsible for variations in the modeled temporal evolution of plasma sheet electron distribution. Our study demonstrates that the effects of realistic ambient magnetic fields need to be incorporated into both the evaluation of resonant diffusion coefficients and the calculation of Fokker-Planck diffusion equation to understand quantitatively the evolution of plasma sheet electron distribution and the occurrence of diffuse aurora, in particular at L > 5 during geomagnetically disturbed periods when the ambient magnetic field considerably deviates from a magnetic dipole.

scholarly journals Penetration of MeV electrons into the mesosphere accompanying pulsating aurorae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Y. Miyoshi ◽  
K. Hosokawa ◽  
S. Kurita ◽  
S.-I. Oyama ◽  
Y. Ogawa ◽  
...  
Keyword(s):  
High Energy ◽  
Daily Basis ◽  
Maximum Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Mesospheric Ozone ◽  
Field Lines ◽  
Eiscat Radar

AbstractPulsating aurorae (PsA) are caused by the intermittent precipitations of magnetospheric electrons (energies of a few keV to a few tens of keV) through wave-particle interactions, thereby depositing most of their energy at altitudes ~ 100 km. However, the maximum energy of precipitated electrons and its impacts on the atmosphere are unknown. Herein, we report unique observations by the European Incoherent Scatter (EISCAT) radar showing electron precipitations ranging from a few hundred keV to a few MeV during a PsA associated with a weak geomagnetic storm. Simultaneously, the Arase spacecraft has observed intense whistler-mode chorus waves at the conjugate location along magnetic field lines. A computer simulation based on the EISCAT observations shows immediate catalytic ozone depletion at the mesospheric altitudes. Since PsA occurs frequently, often in daily basis, and extends its impact over large MLT areas, we anticipate that the PsA possesses a significant forcing to the mesospheric ozone chemistry in high latitudes through high energy electron precipitations. Therefore, the generation of PsA results in the depletion of mesospheric ozone through high-energy electron precipitations caused by whistler-mode chorus waves, which are similar to the well-known effect due to solar energetic protons triggered by solar flares.

scholarly journals Electromagnetic ELF wave intensification associated with fast earthward flows in mid-tail plasma sheet

2012 ◽  
Vol 30 (3) ◽  
pp. 467-488 ◽  
Author(s):  
J. Liang ◽  
B. Ni ◽  
C. M. Cully ◽  
E. F. Donovan ◽  
R. M. Thorne ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Occurrence Rate ◽  
Lower Hybrid ◽  
Angle Distribution ◽  
Frequency Range ◽  
Frequency Wave ◽  
Whistler Mode ◽  
Central Plasma ◽  
Fast Flow ◽  
Flow Activity

Abstract. In this study we perform a statistical survey of the extremely-low-frequency wave activities associated with fast earthward flows in the mid-tail central plasma sheet (CPS) based upon THEMIS measurements. We reveal clear trends of increasing wave intensity with flow enhancement over a broad frequency range, from below fLH (lower-hybrid resonant frequency) to above fce (electron gyrofrequency). We mainly investigate two electromagnetic wave modes, the lower-hybrid waves at frequencies below fLH, and the whistler-mode waves in the frequency range fLH < f < fce. The waves at f < fLH dramatically intensify during fast flow intervals, and tend to contain strong electromagnetic components in the high-plasma-beta CPS region, consistent with the theoretical expectation of the lower-hybrid drift instability in the center region of the tail current sheet. ULF waves with very large perpendicular wavenumber might be Doppler-shifted by the flows and also partly contribute to the observed waves in the lower-hybrid frequency range. The fast flow activity substantially increases the occurrence rate and peak magnitude of the electromagnetic waves in the frequency range fLH < f < fce, though they still tend to be short-lived and sporadic in occurrence. We also find that the electron pitch-angle distribution in the mid-tail CPS undergoes a variation from negative anisotropy (perpendicular temperature smaller than parallel temperature) during weak flow intervals, to more or less positive anisotropy (perpendicular temperature larger than parallel temperature) during fast flow intervals. The flow-related electromagnetic whistler-mode wave tends to occur in conjunction with positive electron anisotropy.

Global distribution of whistler-mode chorus waves observed on the THEMIS spacecraft

2009 ◽  
Vol 36 (9) ◽  
Author(s):  
W. Li ◽  
R. M. Thorne ◽  
V. Angelopoulos ◽  
J. Bortnik ◽  
C. M. Cully ◽  
...  
Keyword(s):  
Global Distribution ◽  
Whistler Mode ◽  
Chorus Waves

Lag-correlated rising tones of electron cyclotron harmonic and whistler-mode upper-band chorus waves

2020 ◽  
Vol 27 (6) ◽  
pp. 062903
Author(s):  
Zhonglei Gao ◽  
Xiongjun Shang ◽  
Pingbing Zuo ◽  
Zhengyang Zou ◽  
Geng Wang ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Cyclotron Harmonic

scholarly journals Resonant scattering of plasma sheet electrons leading to diffuse auroral precipitation: 1. Evaluation for electrostatic electron cyclotron harmonic waves

2011 ◽  
Vol 116 (A4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Binbin Ni ◽  
Richard M. Thorne ◽  
Richard B. Horne ◽  
Nigel P. Meredith ◽  
Yuri Y. Shprits ◽  
...  
Keyword(s):  
Plasma Sheet ◽  
Resonant Scattering ◽  
Electron Cyclotron ◽  
Harmonic Waves ◽  
Cyclotron Harmonic
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