Eigenmodes of the Transverse Alfvénic Resonator at the Plasmapause: A Van Allen Probes Case Study

Mager, P. N.; Mikhailova, Olga S.; Mager, Olga V.; Klimushkin, D. Yu.

doi:10.1029/2018gl079596

Cited by 21 publications

(24 citation statements)

References 40 publications

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“…Azimuthally small-scale ULF waves are excited inside the magnetosphere by various instabilities associated with nonequilibrium distribution of high-energy particle flows (Chelpanov et al, 2018;Hao et al, 2014;Horvath & Lovell, 2019;Klimushkin, 2007). This is confirmed in numerous observational data (Agapitov et al, 2009;Engebretson et al, 1998;Mager et al, 2018;Mann et al, 2002).…”

Section: Introductionsupporting

confidence: 58%

Focusing of Fast Magnetosonic Waves in the Dayside Magnetosphere

Leonovich

Козлов

2020

JGR Space Physics

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The spatial structure of ultra‐low‐frequency (ULF) fast magnetosonic (FMS) waves is calculated in the dayside magnetosphere. A balanced model is developed of a dipole magnetosphere with a plasma rotating in the azimuthal direction. The magnetopause is in the form of a smooth transition layer. It is shown that the largest‐scale FMS eigen harmonics are either weakly unstable or neutrally stable. The calculations show that the eigen oscillation amplitudes increase greatly from the magnetopause into the magnetosphere. Presumably, the dayside magnetosphere plays the role of a sort of focusing lens for ULF FMS waves. Hence, one can expect a significant increase in the magnetosonic oscillation amplitudes in the inner part of the magnetosphere when the FMS oscillations (determining the magnetopause eigen oscillation amplitudes) are amplified in the magnetosheath.

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Section: Introductionsupporting

confidence: 58%

Focusing of Fast Magnetosonic Waves in the Dayside Magnetosphere

Leonovich

Козлов

2020

JGR Space Physics

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“…ULF waves of high azimuthal mode number ( m ) are known to be excited by instabilities. Theoretical works (Leonovich & Mazur, ; Ozeke & Mann, ) suggested that drift‐bounce resonance can excite both fundamental and second harmonic high m standing waves, which have been evidenced by recent observations (e.g., Dai et al, ; Mager et al, ; Takahashi et al, ; Yeoman et al, ). Besides internal sources, medium‐ m or low‐ m ULF waves can be excited by external sources such as interplanetary shocks or dynamic pressure pulses as well (e.g., Eriksson et al, ; Mishin et al, ; Villante et al, ; Zong et al, ;).…”

Section: Introductionmentioning

confidence: 89%

Global‐Scale ULF Waves Associated With SSC Accelerate Magnetospheric Ultrarelativistic Electrons

et al. 2019

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We study electron behavior in the outer radiation belts during the 16 July 2017 storm sudden commencement (SSC), in which prompt intensification of ultrarelativistic electron fluxes was observed at around L = 4.8 by Van Allen Probe B immediately after an interplanetary shock. The electron fluxes in multiple energy channels show clear oscillations in the Pc5 frequency range, although the oscillation characteristics are quite different in different energy channels. At energies above ∼1 MeV, the oscillation periods were very close to the electron drift period, which resembles an energy spectrogram evolution expected for an energetic particle injection event and its drift echoes. At lower energies, however, the oscillation periods hardly depended on the energy: They were very close to the ultralow frequency (ULF) wave period derived from electric field measurements (about 250 s according to wavelet analysis). These complex signatures are consistent with the picture of drift resonance between electrons and short-lived ULF waves with low azimuthal wave numbers. Good agreement between the observations and numerical simulations confirms that shock-induced global-scale ULF waves can efficiently accelerate outer belt ultrarelativistic electrons up to 3.4 MeV over a time scale shorter than 1 hr.

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“…There are three possible reasons for the plasma instability leading to the high‐ m waves generation: inverted parts of the distribution function ( bump on tail distribution), strong gradients of the distribution function, and pressure anisotropy (Chen & Hasegawa, ; Karpman et al, ; Southwood, ). Recent examples of the high‐ m waves driven by the bump on tail instability are presented in Mager et al () and Liu et al (), by the gradient instability in Dai et al (), Rubtsov et al (), and Takahashi et al (), and by the pressure anisotropy in Rae et al (). An interest for the study of the high‐ m waves is caused by their ability to accelerate the charged particles up to very high energies (Ukhorskiy et al, ; Zong et al, ), modulate the fluxes of energetic particles (Chen & Hasegawa, ; Zong et al, ), and serve as substorm triggers (Rae et al, ).…”

Section: Introductionmentioning

confidence: 99%

Conjugate Ionosphere‐Magnetosphere Observations of a Sub‐Alfvénic Compressional Intermediate‐m Wave: A Case Study Using EKB Radar and Van Allen Probes

et al. 2019

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A Pc5 wave was simultaneously observed in the ionosphere by EKB radar and in the magnetosphere by both Van Allen Probe spacecraft within a substorm activity. The wave was located in the nightside, in 1.5‐ to 3‐hr magnetic local time sector, and in the region corresponding to the magnetic shells with maximal distances 4.6–7.8 Earth's radii. As it was found using both the radar and spacecraft data, the wave had frequency of about 1.8 mHz and azimuthal wave number m≈−10; that is, the wave was westward propagating. The EKB radar data revealed the equatorward wave propagating in the ionosphere, which corresponded to the earthward propagation in the magnetosphere. Furthermore, the field‐aligned magnetic component was approximately 2 times larger than both transverse components and accompanied by antiphase pressure oscillations; that is, the wave is compressional and diamagnetic. According to both radar and spacecraft measurements, among two transverse magnetic components, the dominant one was the poloidal. The wave was possibly driven by substorm‐injected energetic protons registered by the spacecraft: the proton fluxes were modulated with the wave frequency at energies of about 90 keV, which corresponded to the energy of the drift wave‐particle resonance. The wave frequency was much lower than the minimal frequency of the field line resonance calculated using the spacecraft data. We conclude that the wave is not the Alfvén mode, but some kind of compressional wave, for example, the drift‐compressional mode.

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Eigenmodes of the Transverse Alfvénic Resonator at the Plasmapause: A Van Allen Probes Case Study

Cited by 21 publications

References 40 publications

Focusing of Fast Magnetosonic Waves in the Dayside Magnetosphere

Focusing of Fast Magnetosonic Waves in the Dayside Magnetosphere

Global‐Scale ULF Waves Associated With SSC Accelerate Magnetospheric Ultrarelativistic Electrons

Conjugate Ionosphere‐Magnetosphere Observations of a Sub‐Alfvénic Compressional Intermediate‐m Wave: A Case Study Using EKB Radar and Van Allen Probes

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