Drift-compression waves propagating in the direction of energetic electron drift in the magnetosphere

Kostarev, Danila; Mager, P. N.

doi:10.12737/stp-33201703

Cited by 16 publications

(10 citation statements)

References 14 publications

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“…The wave studied in this paper can be classified as compressional Pc5 intermediate-m wave generated by the gradient instability via drift resonance with the substorm injected energetic protons. A theory of the gradient instability for the drift-compressional mode is elaborated in Crabtree et al (2003), Kostarev and Mager (2017), and Mager et al (2013).…”

Section: Discussionmentioning

confidence: 99%

“…These waves are characterized by periods longer than Alfvénic periods on the same magnetic shells and by antiphase oscillation of the plasma and the magnetic pressure (diamagnetic property). This kind of the high-m waves can have non-Alfvénic nature, representing the drift-compressional mode (Chelpanov et al, 2016(Chelpanov et al, , 2018Crabtree & Chen, 2004;Kostarev & Mager, 2017;Mager et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

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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“…These waves usually have lower frequencies than the characteristic local Alfvénic frequencies, and they are often observed in the equatorial region of the magnetosphere (Agapitov & Cheremnykh, 2011). Recent radar observations hint that these waves can be identified as the drift compressional mode (DCM; Chelpanov et al, 2016Chelpanov et al, , 2018Mager et al, 2015), which can be excited in hot inhomogeneous plasmas by resonant interaction with energetic protons (Crabtree et al, 2003;Klimushkin & Mager, 2011;Mager et al, 2013) and electrons (Kostarev & Mager, 2017), or via coupling with the shear Alfvén mode (Klimushkin et al, 2012;Mager & Klimushkin, 2017).…”

Section: Introductionmentioning

confidence: 99%

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

et al. 2018

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A compressional Pc5 wave associated with localized hot proton injection was observed by the five THEMIS (Time History of Events and Macroscale Interactions during Substorms) spacecraft in the dusk sector of the Earth's magnetosphere at L ∼ 10R E on 21 May 2007. The wave magnetic field perturbation transverse to the background magnetic field was primarily poloidal, in agreement with the predominately azimuthal wave vector direction (with westward phase velocity). The observation followed two consecutive substorms, when the cloud of energetic particles comprised of the lower-energy protons from the earlier substorm was mixed with higher-energy protons from the subsequent one. The clear signatures of the wave-particle drift resonance of protons modulated by the wave were observed. The wave period was found to be about 2 times longer than the corresponding Alfvén wave eigenmode period on the same L-shells calculated with the THEMIS data. The increase of the particle energy with the distance from the Earth and the observed strong dependence of the wave frequency on the azimuthal wave number constitutes conditions for the gradient instability of the drift compressional mode (for the Alfvén mode one supposes the particle energy decrease with radial distance). Based on these results, we conclude that the observed wave was the drift compressional mode generated by the gradient instability.

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“…Such n and B variations are typical of slow magnetosonic (SM) waves [Van de Hulst, 1951] or mirror mode oscillations [Hasegawa, 1969;Woch et al, 1988] and also indicate the compression nature of oscillations in the magnetosphere. In [Mager et al, 2013;Kostarev, Mager, 2017], compression small-scale oscillations are interpreted using the drift compression wave mode, which also features opposite variations of n and B. However, this mode is recorded mainly during the magnetic storm recovery phase.…”

Section: Observations Of Pulsations On Earth and In The Magnetospherementioning

confidence: 99%

FEATURES OF EXCITATION AND AZIMUTHAL AND MERIDIONAL PROPAGATION OF LONG-PERIOD Pi3 OSCILLATIONS OF THE GEOMAGNETIC FIELD ON DECEMBER 8, 2017

Moiseev

Starodubtsev

Мишин

2020

Solar-Terrestrial Physics

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We study the Pi3 pulsations (with a period T=15–30 min) that were recorded on December 8, 2017 at ground stations in the midnight sector of the magnetosphere at the latitude range of DP2 current system convective electrojets. We have found that Pi3 are especially pronounced in the pre-midnight sector with amplitude of up to 300 nT and duration of up to 2.5 hrs. The pulsation amplitude rapidly decreased with decreasing latitude from F′=72° to F′=63°. The event was recorded during the steady magnetospheric convection. In the southward Bz component of the interplanetary magnetic field, irregular oscillations were detected in the Pi3 frequency range. They correspond to slow magnetosonic waves occurring without noticeable variations in the dynamic pressure Pd. Ground-based geomagnetic observations have shown azimuthal propagation of pulsations with a 0.6–10.6 km/s velocity east and west of the midnight meridian. An analysis of the dynamics of pulsations along the meridian has revealed their propagation to the equator at a velocity 0.75–7.87 km/s. In the projection onto the magnetosphere, the velocities are close in magnitude to the observed propagation velocities of substorm injected electrons. In the dawn-side magnetosphere during ground-observed Pi3 pulsations, compression mode oscillations were recorded. We conclude that propagation of geomagnetic field oscillations in this event depends on the dynamics of particle injections under the action of a large-scale electric field of magnetospheric convection, which causes the plasma to move to Earth due to reconnection in the magnetotail. Small-scale oscillations in the magnetosphere were secondary, excited by the solar wind oscillations penetrating into the magnetosphere.

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Drift-compression waves propagating in the direction of energetic electron drift in the magnetosphere

Cited by 16 publications

References 14 publications

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

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

Drift Resonance of Compressional ULF Waves and Substorm‐Injected Protons From Multipoint THEMIS Measurements

FEATURES OF EXCITATION AND AZIMUTHAL AND MERIDIONAL PROPAGATION OF LONG-PERIOD Pi3 OSCILLATIONS OF THE GEOMAGNETIC FIELD ON DECEMBER 8, 2017

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