Alfvén Wave Generation by a Compact Source Moving on the Magnetopause: Asymptotic Solution

Klimushkin, D. Yu.; Mager, P. N.; Zong, Qiugang; Glaßmeier, Karl‐Heinz

doi:10.1029/2018ja025801

Cited by 9 publications

(10 citation statements)

References 64 publications

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“…With frequencies much smaller than ion cyclotron frequencies, ULF perturbations have been commonly modeled by single‐fluid MHD equations in curved dipole magnetic field (Radoski, 1967; Radoski & Carovillano, 1966). In MHD simulations (e.g., Leonovich et al, 2016; Nakariakov et al, 2016), propagation of ULF perturbations can be well resolved, which essentially depends on scales and dynamics of the perturbation source (e.g., Klimushkin et al, 2019; Wright & Elsden, 2020). Magnetopause dynamics (Hartinger et al, 2013; Plaschke, 2016) or plasmasheet injections (Liu et al, 2017; Runov et al, 2014) can act as the source for ULF perturbations.…”

Section: Introductionmentioning

confidence: 99%

“…Because the ULF perturbation source at the magnetopause can be both temporally and spatially localized (Klimushkin et al, 2019 and references therein), investigations of their propagation (and power spreading) away from the magnetopause require multispacecraft observations combined with ground‐based ULF measurements. An ideal spacecraft configuration would consist of several spacecraft, monitoring both the magnetopause position and the ULF perturbation intensity at different distances from it.…”

Section: Introductionmentioning

confidence: 99%

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Modulation of Whistler Waves by Ultra‐Low‐Frequency Perturbations: The Importance of Magnetopause Location

et al. 2020

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Ultra-low-frequency (ULF, 0.001-1 Hz) perturbations are important aspect of the dynamics in the inner magnetosphere: They are responsible for radial transport (diffusion) of high-energy electrons and for energizing the ionosphere with field-aligned currents. This study is devoted to properties of ULF perturbations generated at the magnetopause, their propagation into the inner magnetosphere, and their modulation of whistler-mode very-low-frequency (VLF) waves. Taking advantage of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission configuration in 2019, we investigate ULF perturbations simultaneously captured by three spacecraft at different distances from the magnetopause. Combining ground-based and THEMIS measurements of ULF perturbations to separate temporal and spatial variations of their properties, we show that their intensity decays exponentially with distance from the magnetopause as close as the geostationary orbit. Near the magnetopause ULF perturbations can modulate whistler-mode (VLF) waves effectively: Close to the magnetopause, VLF wave bursts have the same periodicity as the ULF perturbations. Our results demonstrate that almost the entire outer magnetosphere (from the geostationary orbit to L ∼ 12), including the outer radiation belts, is significantly influenced by ULF perturbations excited by magnetopause dynamic responses to the solar wind.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modulation of Whistler Waves by Ultra‐Low‐Frequency Perturbations: The Importance of Magnetopause Location

et al. 2020

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“…The sources of the waves with small azimuthal numbers (m ∼ 1) are ultimately connected with the solar wind (Agapitov & Cheremnykh, 2013). The waves with large azimuthal wave numbers (m ∼ 50-150) are thought to be generated by particle injections via nonstationary currents due to particle magnetic drift (the moving source theory elaborated in Klimushkin et al, 2019;Mager & Klimushkin, 2007;Zolotukhina, 1974) or kinetic plasma instabilities (Baddeley et al, 2004;Southwood, 1980;Takahashi, 2016). 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, 1991;Karpman et al, 1977;Southwood, 1976).…”

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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“…This is likely an effect of precipitation modulation by ULF waves (Motoba et al., 2013). Such waves preferentially originate from the dawn flank magnetopause due to foreshock transients (Hartinger et al., 2013, 2014), propagate to lower L (Klimushkin et al., 2019; Wright & Elsden, 2020; X. J. Zhang, Angelopoulos, et al., 2020), and modulate the equatorial generation of whistler‐mode chorus waves (W. Li, Thorne, Bortnik, Nishimura, & Angelopoulos, 2011; L. Li et al., 2022; Watt et al., 2011; Xia et al., 2016; X.‐J. Zhang et al., 2019) responsible for electron precipitation.…”

Section: Elfin Observationsmentioning

confidence: 99%

Temporal Scales of Electron Precipitation Driven by Whistler‐Mode Waves

et al. 2023

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Electron resonant scattering by whistler‐mode waves is one of the most important mechanisms responsible for electron precipitation to the Earth's atmosphere. The temporal and spatial scales of such precipitation are dictated by properties of their wave source and background plasma characteristics, which control the efficiency of electron resonant scattering. We investigate these scales with measurements from the two low‐altitude Electron Losses and Fields Investigation (ELFIN) CubeSats that move practically along the same orbit, with along‐track separations ranging from seconds to tens of minutes. Conjunctions with the equatorial THEMIS mission are also used to aid our interpretation. We compare the variations in energetic electron precipitation at the same L‐shells but on successive data collection orbit tracks by the two ELFIN satellites. Variations seen at the smallest inter‐satellite separations, those of less than a few seconds, are likely associated with whistler‐mode chorus elements or with the scale of chorus wave packets (0.1–1 s in time and ∼100 km in space at the equator). Variations between precipitation L‐shell profiles at intermediate inter‐satellite separations, a few seconds to about 1 min, are likely associated with whistler‐mode wave power modulations by ultra‐low frequency waves, that is, with the wave source region (from a few to tens of seconds to a few minutes in time and ∼1,000 km in space at the equator). During these two types of variations, consecutive crossings are associated with precipitation L‐shell profiles very similar to each other. Therefore the spatial and temporal variations at those scales do not change the net electron loss from the outer radiation belt. Variations at the largest range of inter‐satellite separations, several minutes to more than 10 min, are likely associated with mesoscale equatorial plasma structures that are affected by convection (at minutes to tens of minutes temporal variations and ≈[103, 104] km spatial scales). The latter type of variations results in appreciable changes in the precipitation L‐shell profiles and can significantly modify the net electron losses during successive tracks. Thus, such mesoscale variations should be included in simulations of the radiation belt dynamics.

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Alfvén Wave Generation by a Compact Source Moving on the Magnetopause: Asymptotic Solution

Cited by 9 publications

References 64 publications

Modulation of Whistler Waves by Ultra‐Low‐Frequency Perturbations: The Importance of Magnetopause Location

Modulation of Whistler Waves by Ultra‐Low‐Frequency Perturbations: The Importance of Magnetopause Location

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

Temporal Scales of Electron Precipitation Driven by Whistler‐Mode Waves

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