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wave-particle interactions
Authors: de Soria-Santacruz M., Orlova K. G., Martinez-Sanchez M., and Shprits Y Y
Title: Scattering rates of inner belt protons by EMIC waves: A comparison between test particle and diffusion simulations
Abstract: Inner belt energetic protons are a hindrance to development of space technologies. The emission of electromagnetic ion cyclotron (EMIC) waves from spaceborne transmitters has been proposed as a way to solve this problem. The interaction between particles and narrowband emissions has been typically studied using nonlinear test particle simulations. We show that this formulation results in a random walk of the inner belt protons in velocity space. In this paper we compute bounce-averaged pitch angle diffusion rates from test particle simulations and compare them to those of quasi-linear theory for quasi-monochromatic EMIC waves interacting with inner belt protons. We find that the quasi-linear solution is not sensitive to the frequency bandwidth for narrow distributions. Bounce-averaged diff. . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4793–4797 DOI: 10.1002/grl.50925 Available at: http://doi.wiley.com/10.1002/grl.50925
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Authors: Liu Bin, Li Liuyuan, Yu Jiang, and Cao Jinbin
Title: The Effect of Hot Protons on Magnetosonic Waves Inside and Outside the Plasmapause: New Observations and Theoretic Results
Abstract: Based on the wave and proton observations by Van Allen Probes A and B, we examined the effects of hot protons (0.01–50 keV) on fast magnetosonic (MS) waves inside and outside the Earth's plasmasphere. In the low-density plasma trough outside the plasmapause, the gyroresonance interactions between hot protons and MS waves not only cause the MS wave growth at some frequencies but also lead to the damping of MS waves at other frequencies, which depends on the proton phase space density gradient and the ambient plasma density. The gyroresonance of the observed hot protons cannot excite MS waves near the lower hybrid resonance frequency and even causes the MS wave damping. Thus, the frequencies of the observed MS waves outside the plasmapause are usually lower than the lower hybrid resonance . . .
Date: 01/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024676 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024676/full
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Authors: Woodroffe J. R., Jordanova V K, Funsten H O, Streltsov A. V., Bengtson M. T., et al.
Title: Van Allen Probes observations of structured whistler mode activity and coincident electron Landau acceleration inside a remnant plasmaspheric plume
Abstract: We present observations from the Van Allen Probes spacecraft that identify a region of intense whistler mode activity within a large density enhancement outside of the plasmasphere. We speculate that this density enhancement is part of a remnant plasmaspheric plume, with the observed wave being driven by a weakly anisotropic electron injection that drifted into the plume and became nonlinearly unstable to whistler emission. Particle measurements indicate that a significant fraction of thermal (<100 eV) electrons within the plume were subject to Landau acceleration by these waves, an effect that is naturally explained by whistler emission within a gradient and high-density ducting inside a density enhancement.
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA022219 Available at: http://doi.wiley.com/10.1002/2015JA022219
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wave/wave interactions
Authors: Khazanov G. V., Boardsen S., Krivorutsky E. N., Engebretson M. J., Sibeck D., et al.
Title: Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B
Abstract: We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions' polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth . . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022814 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022814
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Authors: Khazanov G. V., Boardsen S., Krivorutsky E. N., Engebretson M. J., Sibeck D., et al.
Title: Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B
Abstract: We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions' polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth . . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics Pages: 449 - 463 DOI: 10.1002/2016JA022814 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022814/full
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waves
Authors: Chen Yaru, Zhou Qinghua, He Yihua, Yang Chang, Liu Si, et al.
Title: Global occurrences of electrostatic electron cyclotron harmonic waves associated with radiation belt electron distributions
Abstract: Electrostatic electron cyclotron harmonic (ECH) waves can yield diffuse aurora primarily at higher L‐shells by driving efficient precipitation loss of plasma sheet electrons. Here using the Van Allen Probes high resolution data, we examine in detail the global occurrences of ECH waves during the period from October 1, 2012 to June 30, 2017 and find that there are totally 419 events of enhanced ECH waves. The statistical results demonstrate that ECH waves can be present over a broad region of L=4‐6 and 00‐24 MLT, with a higher occurrence in the region of L=5‐6 and 06‐19 MLT. The electron phase space density exhibits a distinct ring distribution (∂f/∂v⊥ >0) with the peak energy around a few keV. Both ECH wave events and the electron ring distributions are closely related and . . .
Date: 04/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082668 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082668
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Authors: Osmane Adnane, III Lynn B. Wilson, Blum Lauren, and Pulkkinen Tuija I.
Title: On the Connection Between Microbursts and Nonlinear Electronic Structures in Planetary Radiation Belts
Abstract: Using a dynamical-system approach, we have investigated the efficiency of large-amplitude whistler waves for causing microburst precipitation in planetary radiation belts by modeling the microburst energy and particle fluxes produced as a result of nonlinear wave–particle interactions. We show that wave parameters, consistent with large-amplitude oblique whistlers, can commonly generate microbursts of electrons with hundreds of keV-energies as a result of Landau trapping. Relativistic microbursts (>1 MeV) can also be generated by a similar mechanism, but require waves with large propagation angles ${\theta }_{{kB}}\gt 50^\circ $ and phase-speeds ${v}_{{\rm{\Phi }}}\geqslant c/9$. Using our result for precipitating density and energy fluxes, we argue that holes in the distribution functio. . .
Date: 01/2016 Publisher: The Astrophysical Journal Pages: 51 DOI: 10.3847/0004-637X/816/2/51 Available at: http://stacks.iop.org/0004-637X/816/i=2/a=51?key=crossref.70d237eeae19ada88cf791dd9ba676be
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Authors: Archer M. O., and Plaschke F.
Title: What frequencies of standing surface waves can the subsolar magnetopause support?
Abstract: It is has been proposed that the subsolar magnetopause may support its own eigenmode, consisting of propagating surface waves which reflect at the northern/southern ionospheres forming a standing wave. While the eigenfrequencies of these so-called Kruskal-Schwartzschild (KS) modes have been estimated under typical conditions, the potential distribution of frequencies over the full range of solar wind conditions is not know. Using models of the magnetosphere and magnetosheath applied to an entire solar cycle's worth of solar wind data, we perform time-of-flight calculations yielding a database of KS mode frequencies. Under non-storm times or northward interplanetary magnetic field (IMF), the most likely fundamental frequency is calculated to be inline image mHz, consistent with previous est. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020545 Available at: http://doi.wiley.com/10.1002/2014JA020545
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Waves global model
Authors: de Soria-Santacruz M., Li W, Thorne R M, Ma Q, Bortnik J, et al.
Title: Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis
Abstract: A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the POES spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conjunction events with the Van Allen Probes. These amplitudes are calculated with different input models of the plasma density, wave frequency spectrum, and electron energy spectrum, and the results are compared to the wave observations from the twin Van Allen Probes. Only. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020941 Available at: http://doi.wiley.com/10.1002/2014JA020941
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Authors: de Soria-Santacruz M., Li W, Thorne R M, Ma Q, Bortnik J, et al.
Title: Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations
Abstract: Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth's radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution, or the limited in-situ satellite wave measurements from satellites. This paper evaluates the performance and limitations of a novel technique capable of inferring wave amplitudes from low-altitude electron flux observations from the POES spacecraft, which provide extensive coverage in L-shell and MLT. We found that, within its limitations, this technique could potentially be used to build a dynamic global model of the plasmasp. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021148 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA021148/abstract
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waves in plasmas
Authors: Posch J. L, Engebretson M. J., Olson C. N., Thaller S. A., Breneman A. W., et al.
Title: Low-harmonic magnetosonic waves observed by the Van Allen Probes
Abstract: Purely compressional electromagnetic waves (fast magnetosonic waves), generated at multiple harmonics of the local proton gyrofrequency, have been observed by various types of satellite instruments (fluxgate and search coil magnetometers and electric field sensors), but most recent studies have used data from search coil sensors, and many have been restricted to high harmonics. We report here on a survey of low-harmonic waves, based on electric and magnetic field data from the EFW double probe and EMFISIS fluxgate magnetometer instruments, respectively, on the Van Allen Probes spacecraft during its first full precession through all local times, from October 1, 2012 through July 13, 2014. These waves were observed both inside and outside the plasmapause (PP), at L shells from 2.4 to ~6 (the. . .
Date: 07/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021179 Available at: http://doi.wiley.com/10.1002/2015JA021179
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Waves in plasmasphere
Authors: Ma Q, Li W, Thorne R M, Bortnik J, Reeves G D, et al.
Title: Diffusive transport of several hundred keV electrons in the Earth's slot region
Abstract: We investigate the gradual diffusion of energetic electrons from the inner edge of the outer radiation belt into the slot region. The Van Allen Probes observed slow inward diffusion and decay of ~200-600 keV electrons following the intense geomagnetic storm that occurred on 17 March 2013. During the 10-day non-disturbed period following the storm, the peak of electron fluxes gradually moved from L~2.7 to L~2.4, and the flux levels decreased by a factor of ~2-4 depending on the electron energy. We simulated the radial intrusion and decay of electrons using a 3-dimentional diffusion code, which reproduced the energy-dependent transport of electrons from ~100 keV to 1 MeV in the slot region. At energies of 100-200 keV, the electrons experience fast transport across the slot region due to the . . .
Date: 09/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024452 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024452/full
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Wave‐packet length
Authors: Zhang X.-J., Thorne R., Artemyev A., Mourenas D., Angelopoulos V, et al.
Title: Properties of intense field-aligned lower-band chorus waves: Implications for nonlinear wave-particle interactions
Abstract: Resonant interactions between electrons and chorus waves are responsible for a wide range of phenomena in near‐Earth space (e.g., diffuse aurora, acceleration of MeV electrons, etc.). Although quasi‐linear diffusion is believed to be the primary paradigm for describing such interactions, an increasing number of investigations suggest that nonlinear effects are also important in controlling the rapid dynamics of electrons. However, present models of nonlinear wave‐particle interactions, which have been successfully used to describe individual short‐term events, are not directly applicable for a statistical evaluation of nonlinear effects and the long‐term dynamics of the outer radiation belt, because they lack information on the properties of intense (nonlinearly resonating with e. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025390 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025390
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Wave‐particle interaction
Authors: Ren Jie, Zong Q. G., Zhou X. Z., Spence H E, Funsten H O, et al.
Title: Cold Plasmaspheric Electrons Affected by ULF Waves in the Inner Magnetosphere: A Van Allen Probes Statistical Study
Abstract: Six years of Van Allen Probes data are used to investigate cold plasmaspheric electrons affected by ultralow‐frequency (ULF) waves in the inner magnetosphere (L<7) including spatial distributions, occurrence conditions, and resonant energy range. Events exhibit a global distribution within L= 4–7 but preferentially occur at L∼5.5–7 in the dayside, while there is higher occurrence rate in the duskside than dawnside. They can occur under different geomagnetic activities and solar wind velocities (VS), but the occurrence rates are increasing with larger AE, |SYMH|, and VS. These features are closely associated with the generation and propagation of ULF waves in Pc4 (45–150 s) and Pc5 (150–600 s) bands. Combined with electron observations from HOPE instrument, the resonant energies. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 7954 - 7965 DOI: 10.1029/2019JA027009 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027009
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Authors: Yuan Zhigang, Liu Kun, Yu Xiongdong, Yao Fei, Huang Shiyong, et al.
Title: Precipitation of radiation belt electrons by EMIC waves with conjugated observations of NOAA and Van Allen satellites
Abstract: In this letter, we present unique conjugated satellite observations of MeV relativistic electron precipitation caused by electromagnetic ion cyclotron (EMIC) waves. On the outer boundary of the plasmasphere, the Van Allen probe observed EMIC waves. At ionospheric altitudes, the NOAA 16 satellite at the footprint of Van Allen probe simultaneously detected obvious flux enhancements for precipitating >MeV radiation belt electrons, but not for precipitating MeV radiation belt electrons. Our result provides a direct magnetic conjugated observational link between in‐situ inner magnetospheric EMIC wav. . .
Date: 11/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL080481 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL080481
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Authors: Nakamura S., Omura Y., Kletzing C., and Baker D N
Title: Rapid Precipitation of Relativistic Electron by EMIC Rising‐Tone Emissions Observed by the Van Allen Probes
Abstract: On 23 February 2014, Van Allen Probes sensors observed quite strong electromagnetic ion cyclotron (EMIC) waves in the outer dayside magnetosphere. The maximum amplitude was more than 14 nT, comparable to 7% of the magnitude of the ambient magnetic field. The EMIC waves consisted of a series of coherent rising tone emissions. Rising tones are excited sporadically by energetic protons. At the same time, the probes detected drastic fluctuations in fluxes of MeV electrons. It was found that the electron fluxes decreased by more than 30% during the 1 min following the observation of each EMIC rising tone emissions. Furthermore, it is concluded that the flux reduction is a nonadiabatic (irreversible) process since holes in the particle flux levels appear as drift echoes with energy dispersion. W. . .
Date: May-08-2020 Publisher: Journal of Geophysical Research: Space Physics Pages: 6701 - 6714 DOI: 10.1029/2019JA026772 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026772
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Authors: Mager Pavel N., Mikhailova Olga S., Mager Olga V., and Klimushkin Dmitri Yu.
Title: Eigenmodes of the transverse Alfvénic resonator at the plasmapause: a Van Allen Probes case study
Abstract: A Pc4 ULF wave was detected at spacecraft B of the Van Allen Probes at the plasmapause. A distinctive feature of this wave is the strong periodical modulation of the wave. It is assumed that this modulation is a beating of oscillations close in frequency: at least two harmonics with frequencies of 15.3 and 13.6 MHz are found. It is shown that these harmonics can be the eigenmodes of the transverse resonator at the local maximum of the Alfvén velocity. In addition, the observed wave was in a drift resonance with energetic 80 keV protons and could be generated by an unstable “bump on tail” distribution of protons simultaneously observed with the wave. The estimate of the azimuthal wave number m made from the drift resonance condition gives a value of about −100, i.e., it is a westward. . .
Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079596 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079596
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Authors: Dai Guyue, Su Zhenpeng, Liu Nigang, Wang Bin, Zheng Huinan, et al.
Title: Quenching of Equatorial Magnetosonic Waves by Substorm Proton Injections
Abstract: Near equatorial (fast) magnetosonic waves, characterized by high magnetic compressibility, are whistler‐mode emissions destabilized by proton shell/ring distributions. In the past, substorm proton injections are widely known to intensify magnetosonic waves in the inner magnetosphere. Here we report the unexpected observations by the Van Allen Probes of the magnetosonic wave quenching associated with the substorm proton injections under both high‐ and low‐density conditions. The enhanced proton thermal pressure distorted the background magnetic field configuration and the cold plasma density distribution. The reduced phase velocities locally allowed the weak growth or even damping of magnetosonic waves. Meanwhile, the spatially irregularly varying refractive indices might suppress the. . .
Date: 05/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082944 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082944
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Authors: Hartinger M. D., Claudepierre S G, Turner D. L., Reeves G D, Breneman A., et al.
Title: Diagnosis of ULF Wave-Particle Interactions With Megaelectron Volt Electrons: The Importance of Ultrahigh-Resolution Energy Channels
Abstract: Electron flux measurements are an important diagnostic for interactions between ultralow‐frequency (ULF) waves and relativistic (∼1 MeV) electrons. Since measurements are collected by particle detectors with finite energy channel width, they are affected by a phase mixing process that can obscure these interactions. We demonstrate that ultrahigh‐resolution electron measurements from the Magnetic Electron Ion Spectrometer on the Van Allen Probes mission—obtained using a data product that improves the energy resolution by roughly an order of magnitude—are crucial for understanding ULF wave‐particle interactions. In particular, the ultrahigh‐resolution measurements reveal a range of complex dynamics that cannot be resolved by standard measurements. Furthermore, the standard meas. . .
Date: 10/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL080291 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL080291
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Authors: He Yihua, Xiao Fuliang, Su Zhenpeng, Zheng Huinan, Yang Chang, et al.
Title: Generation of lower L -shell dayside chorus by energetic electrons from the plasmasheet
Abstract: Currently, the generation mechanism for the lower L‐shell dayside chorus has still remained an open question. Here, we report two storm events: 06‐07 March 2016 and 20‐21 January 2016, when Van Allen Probes observed enhanced dayside chorus with lower and higher wave normal angles (the angles between the wave vector and the geomagnetic field) in the region of L = 3.5‐6.3 and MLT = 5.6‐13.5. Hot and energetic (∼ 1‐100 keV) electrons displayed enhancements in fluxes and anisotropy when they were injected from the plasmasheet and drifted from midnight through dawn toward the dayside. Calculations of chorus local growth rates under different waves normal angles show that the upper cutoff and peak wave frequencies display similar patterns to the observations. Chorus growth rates ma. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2017JA024889 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2017JA024889
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Authors: Juhász Lilla, Omura Yoshiharu, Lichtenberger János, and Friedel Reinhard H.
Title: Evaluation of Plasma Properties From Chorus Waves Observed at the Generation Region
Abstract: In this study we present an inversion method which provides thermal plasma population parameters from characteristics of chorus emissions only. Our ultimate goal is to apply this method to ground‐based data in order to derive the lower‐energy boundary condition for many radiation belt models. The first step is to test the chorus inversion method on in situ data of the Van Allen Probes in the generation region. The density and thermal velocity of energetic electrons (few kiloelectron volts to 100 keV) are derived from frequency sweep rate and starting frequencies of chorus emissions through analysis of wave data from the Electric and Magnetic Field Instrument Suite and Integrated Science on board the Van Allen Probes. The nonlinear wave growth theory of Omura and Nunn (2011, https://doi. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026337 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026337
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wave‐particle interactions
Authors: Li W, and Hudson M.K.
Title: Earth's Van Allen Radiation Belts: From Discovery to the Van Allen Probes Era
Abstract: Discovery of the Earth's Van Allen radiation belts by instruments flown on Explorer 1 in 1958 was the first major discovery of the Space Age. The observation of distinct inner and outer zones of trapped megaelectron volt (MeV) particles, primarily protons at low altitude and electrons at high altitude, led to early models for source and loss mechanisms including Cosmic Ray Albedo Neutron Decay for inner zone protons, radial diffusion for outer zone electrons and loss to the atmosphere due to pitch angle scattering. This scattering lowers the mirror altitude for particles in their bounce motion parallel to the Earth's magnetic field until they suffer collisional loss. A view of the belts as quasi‐static inner and outer zones of energetic particles with different sources was modified by ob. . .
Date: 11/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025940 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025940
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Authors: Watt C. E. J., Allison H. J., Meredith N P, Thompson R. L., Bentley S. N., et al.
Title: Variability of Quasilinear Diffusion Coefficients for Plasmaspheric Hiss
Abstract: In the outer radiation belt, the acceleration and loss of high‐energy electrons is largely controlled by wave‐particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small‐scale physics of wave‐particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density, and composition. For plasmaspheric hiss in the magnetosphere, observations indicate large variations in the wave intensity and wave normal angle, but less is known about the simultaneous variability of the magnetic field and number density. We use in situ measurements. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026401 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026401
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Authors: Agapitov O., Mourenas D., Artemyev A., Hospodarsky G., and Bonnell J.W.
Title: Timescales for electron quasi‐linear diffusion by lower‐band chorus waves: the effects of ω pe / Ω ce dependence on geomagnetic activity
Abstract: Electron scattering by chorus waves is an important mechanism that can lead to fast electron acceleration and loss in the outer radiation belt. Making use of Van Allen Probes measurements, we present the first statistical survey of megaelectron volt electron pitch angle and energy quasi‐linear diffusion rates by chorus waves as a function of L‐shell, local time, and AE index, taking into account the local electron plasma frequency to gyrofrequency ratio ωpe/Ωce, chorus wave frequency, and resonance wave amplitude. We demonstrate that during disturbed periods, ωpe/Ωce strongly decreases in the night sector, leading to a faster electron loss but also a much faster electron energization in two distinct regions just above the plasmapause and at L ~ 3.5–5.5. Spatiotemporal variations . . .
Date: 05/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083446 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083446
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Authors: Turner D. L., Kilpua E. K. J., Hietala H., Claudepierre S G, O'Brien T P, et al.
Title: The Response of Earth's Electron Radiation Belts to Geomagnetic Storms: Statistics From the Van Allen Probes Era Including Effects From Different Storm Drivers
Abstract: A statistical study was conducted of Earth's radiation belt electron response to geomagnetic storms using NASA's Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L‐shell, energy, and epoch time during 110 storms with SYM‐H ≤−50 nT during September 2012 to September 2017 (inclusive). The radiation belt response revealed clear energy and L‐shell dependencies, with tens of keV electrons enhanced at all L‐shells (2.5 ≤ L ≤ 6) in all storms during the storm commencement and main phase and then quickly decaying away during the early recovery phase, low hundreds of keV electrons enhanced at lower L‐shells (~3 ≤ L ≤ ~4) in upward of 90% of all storms and then decaying gradually during the rec. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026066 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026066
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Authors: Cao Xing, Ni Binbin, Summers Danny, Shprits Yuri Y, Gu Xudong, et al.
Title: Sensitivity of EMIC Wave-Driven Scattering Loss of Ring Current Protons to Wave Normal Angle Distribution
Abstract: Electromagnetic ion cyclotron waves have long been recognized to play a crucial role in the dynamic loss of ring current protons. While the field‐aligned propagation approximation of electromagnetic ion cyclotron waves was widely used to quantify the scattering loss of ring current protons, in this study, we find that the wave normal distribution strongly affects the pitch angle scattering efficiency of protons. Increase of peak normal angle or angular width can considerably reduce the scattering rates of ≤10 keV protons. For >10 keV protons, the field‐aligned propagation approximation results in a pronounced underestimate of the scattering of intermediate equatorial pitch angle protons and overestimates the scattering of high equatorial pitch angle protons by orders of magnitude. Ou. . .
Date: 01/2019 Publisher: Geophysical Research Letters Pages: 590 - 598 DOI: 10.1029/2018GL081550 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL081550
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Authors: Li Li, Zhou Xu-Zhi, Omura Yoshiharu, Wang Zi-Han, Zong Qiu-Gang, et al.
Title: Nonlinear drift resonance between charged particles and ultra-low frequency waves: Theory and Observations
Abstract: In Earth's inner magnetosphere, electromagnetic waves in the ultra‐low frequency (ULF) range play an important role in accelerating and diffusing charged particles via drift resonance. In conventional drift‐resonance theory, linearization is applied under the assumption of weak wave‐particle energy exchange so particle trajectories are unperturbed. For ULF waves with larger amplitudes and/or durations, however, the conventional theory becomes inaccurate since particle trajectories are strongly perturbed. Here, we extend the drift‐resonance theory into a nonlinear regime, to formulate nonlinear trapping of particles in a wave‐carried potential well, and predict the corresponding observable signatures such as rolled‐up structures in particle energy spectrum. After considering how. . .
Date: 08/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079038 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079038
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wave‐wave interaction
Authors: Teng S., Zhao J., Tao X., Wang S., and Reeves G D
Title: Observation of Oblique Lower Band Chorus Generated by Nonlinear Three-Wave Interaction
Abstract: Oblique whistler mode waves have been suggested to play an important role in radiation belt electron dynamics. Recently, Fu et al. [2017] proposed that highly oblique lower band whistler waves could be generated by nonlinear three‐wave resonance. Here we present the first observational evidence of such process, using Van Allen Probes data, where an oblique lower band chorus wave is generated by two quasi‐parallel waves through nonlinear three‐wave interaction. The wave resonance condition is satisfied even in the presence of frequency chirping of one of the pump waves. Different from the simulation results of Fu et al. [2017], simultaneous particle data do not show a plateau in the electron distribution, which could be due to the very weak intensity of the generated waves. These resu. . .
Date: 06/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078765 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078765
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wedgelet
Authors: Palin L., Jacquey C., Opgenoorth H., Connors M., Sergeev V., et al.
Title: Three-dimensional current systems and ionospheric effects associated with small dipolarisation fronts
Abstract: We present a case study of eight successive plasma sheet (PS) activations (usually referred to as bursty bulk flows or dipolarization fronts ) associated with small individual inline image increases on 31 March 2009 (0200–0900 UT), observed by the THEMIS mission. This series of events happens during very quiet solar wind conditions, over a period of 7 hours preceding a substorm onset at 1230 UT. The amplitude of the dipolarizations increases with time. The low-amplitude dipolarization fronts are associated with few (1 or 2) rapid flux transport events (RFT, Eh > 2mV/m), whereas the large-amplitude ones encompass many more RFT events. All PS activations are associated with small and localized substorm current wedge (SCW) like current system signatures, which seems to be the consequenc. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021040 Available at: http://doi.wiley.com/10.1002/2015JA021040
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Weimer electric field model
Authors: Ferradas C. P., Zhang J.-C., Spence H E, Kistler L. M., Larsen B A, et al.
Title: Temporal evolution of ion spectral structures during a geomagnetic storm: Observations and modeling
Abstract: Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron (HOPE) mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1-~50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convection electric field. Prior to the beginning of the storm, the plasma sheet inner edge exhibits narrow nose spectral structures that vary little in energy across L values. Ion access to the inner magnetosphere during these times is limited to the nose energy bands. As co. . .
Date: 12/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024702 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024702/full
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Authors: Ferradas C. P., Jordanova V K, Reeves G D, and Larsen B A
Title: Comparison of Electron Loss Models in the Inner Magnetosphere During the 2013 St. Patrick's Day Geomagnetic Storm
Abstract: Electrons with energies in the keV range play an important role in the dynamics of the inner magnetosphere. Therefore, accurately modeling electron fluxes in this region is of great interest. However, these calculations constitute a challenging task since the lifetimes of electrons that are available have limitations. In this study, we simulate electron fluxes in the energy range of 20 eV to 100 keV to assess how well different electron loss models can account for the observed electron fluxes during the Geospace Environment Modelling Challenge Event of the 2013 St. Patrick's Day storm. Three models (Case 1, Case 2, and Case 3) of electron lifetimes due to wave‐induced pitch angle scattering are used to compute the fluxes, which are compared with measurements from the Van Allen Probes. Th. . .
Date: 09/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 7872 - 7888 DOI: 10.1029/2019JA026649 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026649
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Authors: Ferradas C. P., Zhang J.-C., Spence H E, Kistler L. M., Larsen B A, et al.
Title: Drift paths of ions composing multiple-nose spectral structures near the inner edge of the plasma sheet
Abstract: We present a case study of the H+, He+, and O+ multiple-nose structures observed by the Helium, Oxygen, Proton, and Electron instrument on board Van Allen Probe A over one complete orbit on 28 September 2013. Nose structures are observed near the inner edge of the plasma sheet and constitute the signatures of ion drift in the highly dynamic environment of the inner magnetosphere. We find that the multiple noses are intrinsically associated with variations in the solar wind. Backward ion drift path tracings show new details of the drift trajectories of these ions; i.e., multiple noses are formed by ions with a short drift time from the assumed source location to the inner region and whose trajectories (1) encircle the Earth different number of times or (2) encircle the Earth equal number of. . .
Date: 11/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071359 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071359/full
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whistler
Authors: Colpitts C. A., Cattell C. A., Engebretson M., Broughton M., Tian S., et al.
Title: Van Allen Probes observations of cross-scale coupling between electromagnetic ion cyclotron waves and higher-frequency wave modes
Abstract: We present observations of higher-frequency (~50–2500 Hz, ~0.1–0.7 fce) wave modes modulated at the frequency of colocated lower frequency (0.5–2 Hz, on the order of fci) waves. These observations come from the Van Allen Probes Electric Field and Waves instrument's burst mode data and represent the first observations of coupling between waves in these frequency ranges. The higher-frequency wave modes, typically whistler mode hiss and chorus or magnetosonic waves, last for a few to a few tens of seconds but are in some cases observed repeatedly over several hours. The higher-frequency waves are observed to be unmodulated before and after the presence of the electromagnetic ion cyclotron (EMIC) waves, but when the EMIC waves are present, the amplitude of the higher-frequency waves . . .
Date: 11/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071566 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071566/full
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Authors: Crabtree Chris, Tejero Erik, Ganguli Gurudas, Hospodarsky George B., and Kletzing Craig A.
Title: Bayesian Spectral Analysis of Chorus Sub-Elements from the Van Allen Probes
Abstract: We develop a Bayesian spectral analysis technique that calculates the probability distribution functions of a superposition of wave-modes each described by a linear growth rate, a frequency and a chirp rate. The Bayesian framework has a number of advantages, including 1) reducing the parameter space by integrating over the amplitude and phase of the wave, 2) incorporating the data from each channel to determine the model parameters such as frequency which leads to high resolution results in frequency and time, 3) the ability to consider the superposition of waves where the wave-parameters are closely spaced, 4) the ability to directly calculate the expectation value of wave parameters without resorting to ensemble averages, 5) the ability to calculate error bars on model parameters. We exa. . .
Date: 04/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023547 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023547/full
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Authors: Nunn David, and Omura Yoshiharu
Title: A computational and theoretical investigation of nonlinear wave-particle interactions in oblique whistlers
Abstract: Most previous work on nonlinear wave-particle interactions between energetic electrons and VLF waves in the Earth's magnetosphere has assumed parallel propagation, the underlying mechanism being nonlinear trapping of cyclotron resonant electrons in a parabolic magnetic field inhomogeneity. Here nonlinear wave-particle interaction in oblique whistlers in the Earth's magnetosphere is investigated. The study is nonself-consistent and assumes an arbitrarily chosen wave field. We employ a “continuous wave” wave field with constant frequency and amplitude, and a model for an individual VLF chorus element. We derive the equations of motion and trapping conditions in oblique whistlers. The resonant particle distribution function, resonant current, and nonlinear growth rate are computed as func. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020898 Available at: http://doi.wiley.com/10.1002/2014JA020898
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whistler chorus
Authors: Kim Jin-Hee, Lee Dae-Young, Cho Jung-Hee, Shin Dae-Kyu, Kim Kyung-Chan, et al.
Title: A prediction model for the global distribution of whistler chorus wave amplitude developed separately for two latitudinal zones
Abstract: Whistler mode chorus waves are considered to play a central role in accelerating and scattering electrons in the outer radiation belt. While in situ measurements are usually limited to the trajectories of a small number of satellites, rigorous theoretical modeling requires a global distribution of chorus wave characteristics. In the present work, by using a large database of chorus wave observations made on the Time History of Events and Macroscale Interactions during Substorms satellites for about 5 years, we develop prediction models for a global distribution of chorus amplitudes. The development is based on two main components: (a) the temporal dependence of average chorus amplitudes determined by correlating with the preceding solar wind and geomagnetic conditions as represented by t. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020900 Available at: http://doi.wiley.com/10.1002/2014JA020900
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whistler intensity modulation
Authors: Tao X.
Title: A numerical study of chorus generation and the related variation of wave intensity using the DAWN code
Abstract: Chorus waves play an important role in energetic electron dynamics in the inner magnetosphere. In this work, we present a new hybrid code, DAWN, to simulate the generation of chorus waves. The DAWN code is unique in that it models cold electrons using linearized fluid equations and hot electrons using particle-in-cell techniques. The simplified fluid equations can be solved with robust and simple algorithms. We demonstrate that discrete chorus elements can be generated using the code. Waveforms of the generated element show amplitude modulation or “subpackets,” and the frequency sweep rate of the generated element is found to be consistent with that of observed chorus waves. Using the DAWN code, we then investigate the variation of wave intensity (inline image) with respect to linear g. . .
Date: 05/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 3362 - 3372 DOI: 10.1002/2014JA019820 Available at: http://doi.wiley.com/10.1002/2014JA019820
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whistler mode
Authors: Záhlava J., Němec F., Santolik O, Kolmašová I., Hospodarsky G B, et al.
Title: Lightning Contribution to Overall Whistler Mode Wave Intensities in the Plasmasphere
Abstract: Electromagnetic waves generated by lightning propagate into the plasmasphere as dispersed whistlers. They can therefore influence the overall wave intensity in space, which, in turn, is important for dynamics of the Van Allen radiation belts. We analyze spacecraft measurements in low‐Earth orbit as well as in high‐altitude equatorial region, together with a ground‐based estimate of lightning activity. We accumulate wave intensities when the spacecraft are magnetically connected to thunderstorms and compare them with measurements obtained when thunderstorms are absent. We show that strong lightning activity substantially affects the wave intensity in a wide range of L‐shells and altitudes. The effect is observed mainly between 500 Hz and 4 kHz, but its frequency range strongly varie. . .
Date: 07/2019 Publisher: Geophysical Research Letters Pages: 8607 - 8616 DOI: 10.1029/2019GL083918 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083918
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Authors: Yu Xiongdong, Yuan Zhigang, Huang Shiyong, Yao Fei, Qiao Zheng, et al.
Title: Excitation of extremely low-frequency chorus emissions: The role of background plasma density
Abstract: Low‐frequency chorus emissions have recently attracted much attention due to the suggestion that they may play important roles in the dynamics of the Van Allen Belts. However, the mechanism (s) generating these low‐frequency chorus emissions have not been well understood. . In this letter, we report an interesting case in which background plasma density lowered the lower cutoff frequency of chorus emissions from above 0.1 f ce (typical ordinary chorus) to 0.02 f ce (extremely low‐frequency chorus). Those extremely low‐frequency chorus waves were observed in a rather dense plasma, where the number density N e was found to be several times larger than has been associated with observations of ordinary chorus waves. For suprathermal electrons whose free energy is supplied by anisotropi. . .
Date: 02/2019 Publisher: Earth and Planetary Physics Pages: 1 - 7 DOI: 10.26464/epp2019001 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.26464/epp2019001
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Authors: Li Jinxing, Bortnik Jacob, Li Wen, Thorne Richard M, Ma Qianli, et al.
Title: Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales
Abstract: Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to ~4.3 RE over 3 h during a relatively quiet period. The modulation of 150–500 Hz plasmaspheric hiss was correlated with whistler mode waves measured outside the plasmasphere across 3 h in magnetic local time and 3 L shells, revealing that the modulation was temporal in nature. We suggest that the coherent modulation of whistler mode waves was associated with the coherent ULF waves measured ov. . .
Date: 02/2017 Publisher: Journal of Geophysical Research: Space Physics Pages: 1871-1882 DOI: 10.1002/2016JA023706 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023706/full
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Authors: Li Jinxing, Bortnik Jacob, Li Wen, Thorne Richard M., Ma Qianli, et al.
Title: Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales
Abstract: Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to ~4.3 RE over 3 h during a relatively quiet period. The modulation of 150–500 Hz plasmaspheric hiss was correlated with whistler mode waves measured outside the plasmasphere across 3 h in magnetic local time and 3 L shells, revealing that the modulation was temporal in nature. We suggest that the coherent modulation of whistler mode waves was associated with the coherent ULF waves measured ov. . .
Date: 02/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023706 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023706/full
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whistler mode chorus
Authors: Kurita Satoshi, Miyoshi Yoshizumi, Blake Bernard, Reeves Geoffery D., and Kletzing Craig A.
Title: Relativistic electron microbursts and variations in trapped MeV electron fluxes during the 8-9 October 2012 storm: SAMPEX and Van Allen Probes observations
Abstract: It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Relativistic electron microbursts have been considered as an important loss mechanism of radiation belt electrons. Here we report on the observations of relativistic electron microbursts and flux variations of trapped MeV electrons during the 8–9 October 2012 storm, using the SAMPEX and Van Allen Probes satellites. Observations by the satellites show that relativistic electron microbursts correlate well with the rapid enhancement of trapped MeV electron fluxes by chorus wave-particle interactions, indicating that acceleration by chorus is much more efficient than losses by microbursts during the storm. It . . .
Date: 02/2016 Publisher: Geophysical Research Letters Pages: n/a - n/a DOI: 10.1002/2016GL068260 Available at: http://doi.wiley.com/10.1002/2016GL068260http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2016GL068260
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Authors: Hartley D. P., Kletzing C A, Kurth W S, Bounds S R, Averkamp T. F., et al.
Title: Using the cold plasma dispersion relation and whistler-mode waves to quantify the antenna sheath impedance of the Van Allen Probes EFW instrument
Abstract: Cold plasma theory and parallel wave propagation are often assumed when approximating the whistler mode magnetic field wave power from electric field observations. The current study is the first to include the wave normal angle from the Electric and Magnetic Field Instrument Suite and Integrated Science package on board the Van Allen Probes in the conversion factor, thus allowing for the accuracy of these assumptions to be quantified. Results indicate that removing the assumption of parallel propagation does not significantly affect calculated plasmaspheric hiss wave powers. Hence, the assumption of parallel propagation is valid. For chorus waves, inclusion of the wave normal angle in the conversion factor leads to significant alterations in the distribution of wave power ratios (observed/. . .
Date: 05/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022501 Available at: http://doi.wiley.com/10.1002/2016JA022501
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Authors: Yue Chao, Chen Lunjin, Bortnik Jacob, Ma Qianli, Thorne Richard M, et al.
Title: The characteristic response of whistler mode waves to interplanetary shocks
Abstract: Magnetospheric whistler mode waves play a key role in regulating the dynamics of the electron radiation belts. Recent satellite observations indicate a significant influence of interplanetary (IP) shocks on whistler mode wave power in the inner magnetosphere. In this study, we statistically investigate the response of whistler mode chorus and plasmaspheric hiss to IP shocks based on Van Allen Probes and THEMIS satellite observations. Immediately after the IP shock arrival, chorus wave power is usually intensified, often at post-midnight to pre-noon sector, while plasmaspheric hiss wave power predominantly decreases near the dayside but intensifies near the nightside. We conclude that chorus wave intensification outside the plasmasphere is probably associated with the suprathermal electron . . .
Date: 09/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024574 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024574/full
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whistler mode chorus waves
Authors: Anderson B. R., Shekhar S., Millan R M, Crew A. B., Spence H E, et al.
Title: Spatial Scale and Duration of One Microburst Region on 13 August 2015
Abstract: Prior studies of microburst precipitation have largely relied on estimates of the spatial scale and temporal duration of the microburst region in order to determine the radiation belt loss rate of relativistic electrons. These estimates have often relied on the statistical distribution of microburst events. However, few studies have directly observed the spatial and temporal evolution of a single microburst event. In this study, we combine BARREL balloon-borne X-ray measurements with FIREBIRD-II and AeroCube-6 CubeSat electron measurements to determine the spatial and temporal evolution of a microburst region in the morning MLT sector on 13 August 2015. The microburst region is found to extend across at least four hours in local time in the morning sector, from 09:00 to 13:00 MLT, and from. . .
Date: 04/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023752 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023752/full
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Authors: Yue Chao, An Xin, Bortnik Jacob, Ma Qianli, Li Wen, et al.
Title: The relationship between the macroscopic state of electrons and the properties of chorus waves observed by the Van Allen Probes
Abstract: Plasma kinetic theory predicts that a sufficiently anisotropic electron distribution will excite whistler mode waves, which in turn relax the electron distribution in such a way as to create an upper bound on the relaxed electron anisotropy. Here using whistler mode chorus wave and plasma measurements by Van Allen Probes, we confirm that the electron distributions are well constrained by this instability to a marginally stable state in the whistler mode chorus waves generation region. Lower band chorus waves are organized by the electron β∥e into two distinct groups: (i) relatively large-amplitude, quasi-parallel waves with inline image and (ii) relatively small-amplitude, oblique waves with inline image. The upper band chorus waves also have enhanced amplitudes close to the instabili. . .
Date: 08/2016 Publisher: Geophysical Research Letters Pages: 7804 - 7812 DOI: 10.1002/2016GL070084 Available at: http://doi.wiley.com/10.1002/2016GL070084
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whistler mode wave
Authors: Kurita Satoshi, Kadokura Akira, Miyoshi Yoshizumi, Morioka Akira, Sato Yuka, et al.
Title: Relativistic electron precipitations in association with diffuse aurora: Conjugate observation of SAMPEX and the all sky TV camera at Syowa Station
Abstract: It has been believed that whistler mode waves can cause relativistic electron precipitations. It has been also pointed out that pitch angle scattering of ~keV electrons by whistler mode waves results in diffuse auroras. Thus, it is natural to expect relativistic electron precipitations associated with diffuse auroras. Based on a conjugate observation between the SAMPEX spacecraft and the all-sky TV camera at Syowa Station, we report, for the first time, a case in which relativistic electron precipitations are associated with diffuse aurora. The SAMPEX observation shows that the precipitations of >1 MeV electrons are well accompanied with those of >150 and >400 keV electrons. This indicates that electrons in the energy range from several keV to >1 MeV precipitate into the atmosphere s. . .
Date: 06/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064564 Available at: http://doi.wiley.com/10.1002/2015GL064564
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Authors: Li W, Shen X.‐C., Ma Q, Capannolo L., Shi R., et al.
Title: Quantification of Energetic Electron Precipitation Driven by Plume Whistler Mode Waves, Plasmaspheric Hiss, and Exohiss
Abstract: Whistler mode waves are important for precipitating energetic electrons into Earth's upper atmosphere, while the quantitative effect of each type of whistler mode wave on electron precipitation is not well understood. In this letter, we evaluate energetic electron precipitation driven by three types of whistler mode waves: plume whistler mode waves, plasmaspheric hiss, and exohiss observed outside the plasmapause. By quantitatively analyzing three conjunction events between Van Allen Probes and POES/MetOp satellites, together with quasi‐linear calculation, we found that plume whistler mode waves are most effective in pitch angle scattering loss, particularly for the electrons from tens to hundreds of keV. Our new finding provides the first direct evidence of effective pitch angle scatter. . .
Date: 03/2019 Publisher: Geophysical Research Letters Pages: 3615 - 3624 DOI: 10.1029/2019GL082095 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082095
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whistler mode waves
Authors: Shi Run, Li Wen, Ma Qianli, Green Alex, Kletzing Craig A., et al.
Title: Properties of Whistler Mode Waves in Earth's Plasmasphere and Plumes
Abstract: Whistler mode wave properties inside the plasmasphere and plumes are systematically investigated using 5‐year data from Van Allen Probes. The occurrence and intensity of whistler mode waves in the plasmasphere and plumes exhibit dependences on magnetic local time, L, and AE. Based on the dependence of the wave normal angle and Poynting flux direction on L shell and normalized wave frequency to electron cyclotron frequency (fce), whistler mode waves are categorized into four types. Type I: ~0.5 fce with oblique wave normal angles mostly in plumes; Type II: 0.01–0.5 fce with small wave normal angles in the outer plasmasphere or inside plumes; Type III: <0.01 fce with oblique wave normal angles mostly within the plasmasphere or plumes; Type IV: 0.05–0.5 fce with oblique wave normal angl. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026041 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026041
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Authors: Summers Danny, Omura Yoshiharu, Nakamura Satoko, and Kletzing Craig A.
Title: Fine structure of plasmaspheric hiss
Abstract: Plasmaspheric hiss has been widely regarded as a broadband, structureless, incoherent emission. In this study, by examining burst-mode vector waveform data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on the Van Allen Probes mission, we show that plasmaspheric hiss is a coherent emission with complex fine structure. Specifically, plasmaspheric hiss appears as discrete rising tone and falling tone elements. Our study comprises the analysis of two one-hour samples within which a total of 8 one-second samples were analyzed. By means of waveform analysis on two samples we identify typical amplitudes, phase profiles, and sweep rates of the rising and falling tone elements. The exciting new observations reported here can be expected to fuel a . . .
Date: 12/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020437 Available at: http://doi.wiley.com/10.1002/2014JA020437
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