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

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

2021 ◽  
Author(s):  
Zhonglei Gao
Keyword(s):  
Electron Cyclotron ◽  
Hot Electrons ◽  
Time Lags ◽  
Discrete Elements ◽  
Loss Cone ◽  
Whistler Mode ◽  
Chorus Waves ◽  
Van Allen Probes ◽  
Gain Energy ◽  
Cyclotron Harmonic

<p>Electron cyclotron harmonic (ECH) and whistler-mode chorus waves can contribute significantly to the magnetospheric dynamics. In the frequency-time spectrogram, ECH usually appears as a series of harmonic structureless bands, while chorus often exhibits successive discrete elements. Here, we present surprising observations by Van Allen Probes of lag-correlated rising tones of ECH and upper-band chorus waves. The time lags of ECH elements with respect to chorus elements range from 0.05 to 0.28 s, negatively correlated with the chorus peak amplitudes. The ECH elements seemingly emerge only when the chorus elements are sufficiently intense (peak amplitude >3 mV/m), and their peak amplitudes are positively correlated. Our data and modeling suggest that upper-band chorus may promote the generation of ECH through rapidly precipitating the ~keV electrons near the loss cone. This phenomenon implies that ECH and chorus may not grow independently but competitively or collaboratively gain energy from hot electrons.</p>

scholarly journals Nonlinear Coupling Between Whistler‐Mode Chorus and Electron Cyclotron Harmonic Waves in the Magnetosphere

2018 ◽  
Vol 45 (23) ◽  
Author(s):  
Zhonglei Gao ◽  
Zhenpeng Su ◽  
Fuliang Xiao ◽  
Danny Summers ◽  
Nigang Liu ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Harmonic Waves ◽  
Nonlinear Coupling ◽  
Whistler Mode ◽  
Cyclotron Harmonic

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 Radial variation of whistler-mode chorus: first results from the STAFF/DWP instrument on board the Double Star TC-1 spacecraft

2005 ◽  
Vol 23 (8) ◽  
pp. 2937-2942 ◽  
Author(s):  
O. Santolík ◽  
E. Macúšová ◽  
K. H. Yearby ◽  
N. Cornilleau-Wehrlin ◽  
H. StC. K. Alleyne
Keyword(s):  
Cyclotron Frequency ◽  
Power Spectra ◽  
Double Star ◽  
Electron Cyclotron ◽  
Radial Variation ◽  
Whistler Mode ◽  
Electron Cyclotron Frequency ◽  
The Earth ◽  
First Results ◽  
Initial Results

Abstract. We use the first measurements of the STAFF/DWP instrument on the Double Star TC-1 spacecraft to investigate whistler-mode chorus. We present initial results of a systematic study on radial variation of dawn chorus. The chorus events show an increased intensity at L parameter above 6. This is important for the possible explanation of intensifications of chorus, which were previously observed closer to the Earth at higher latitudes. Our results also indicate that the upper band of chorus at frequencies above one-half of the electron cyclotron frequency disappears for L above 8. The lower band of chorus is observed at frequencies below 0.4 of the electron cyclotron frequency up to L of 11-12. The maxima of the chorus power spectra are found at slightly lower frequencies compared to previous studies. We do not observe any distinct evolution of the position of the chorus frequency band as a function of L. More data of the TC-1 spacecraft are needed to verify these initial results and to increase the MLT coverage.

Expansions of the mildly relativistic dispersion function for nearly perpendicular electron cyclotron ray tracing

1999 ◽  
Vol 61 (1) ◽  
pp. 121-128 ◽  
Author(s):  
I. P. SHKAROFSKY
Keyword(s):  
Ray Tracing ◽  
Computer Programs ◽  
Higher Order ◽  
Electron Cyclotron ◽  
Dispersion Function ◽  
Relativistic Dispersion ◽  
Plasma Dispersion ◽  
Derivatives Of ◽  
Cyclotron Harmonic ◽  
Experienced Difficulty

To trace rays very close to the nth electron cyclotron harmonic, we need the mildly relativistic plasma dispersion function and its higher-order derivatives. Expressions for these functions have been obtained as an expansion for nearly perpendicular propagation in a region where computer programs have previously experienced difficulty in accuracy, namely when the magnitude of (c/vt)2 (ω−nωc)/ω is between 1 and 10. In this region, the large-argument expansions are not yet valid, but partial cancellations of terms occur. The expansion is expressed as a sum over derivatives of the ordinary dispersion function Z. New expressions are derived to relate higher-order derivatives of Z to Z itself in this region of concern in terms of a finite series.

scholarly journals Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
X. Tao ◽  
R. M. Thorne ◽  
R. B. Horne ◽  
S. Grimald ◽  
C. S. Arridge ◽  
...  
Keyword(s):  
Electron Cyclotron ◽  
Harmonic Waves ◽  
Cyclotron Harmonic
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