Biblio

Found 232 results
Filters: First Letter Of Last Name is A  [Clear All Filters]
2019
Authors: Da Silva L. A., Sibeck D., Alves L. R., Souza V. M., Jauer P. R., et al.
Title: Contribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014
Abstract: Energy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how Ultra Low Frequency (ULF) wave activity during the passage of Alfvénic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron fluxes from the background. We found that the global recovery that started on September 22, 2014, which coincides with the co. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026184 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026184
More Details
Authors: Da Silva L. A., Sibeck D., Alves L. R., Souza V. M., Jauer P. R., et al.
Title: Contribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014
Abstract: Energy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how Ultra Low Frequency (ULF) wave activity during the passage of Alfvénic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron fluxes from the background. We found that the global recovery that started on September 22, 2014, which coincides with the co. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026184 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026184
More Details
Authors: Da Silva L. A., Sibeck D., Alves L. R., Souza V. M., Jauer P. R., et al.
Title: Contribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014
Abstract: Energy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how Ultra Low Frequency (ULF) wave activity during the passage of Alfvénic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron fluxes from the background. We found that the global recovery that started on September 22, 2014, which coincides with the co. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026184 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026184
More Details
Authors: Pinto V. A., Mourenas D., Bortnik J, Zhang X.‐J., Artemyev A. V., et al.
Title: Decay of Ultrarelativistic Remnant Belt Electrons Through Scattering by Plasmaspheric Hiss
Abstract: Ultrarelativistic electron remnant belts appear frequently following geomagnetic disturbances and are located in‐between the inner radiation belt and a reforming outer belt. As remnant belts are relatively stable, here we explore the importance of hiss and electromagnetic ion cyclotron waves in controlling the observed decay rates of remnant belt ultrarelativistic electrons in a statistical way. Using measurements from the Van Allen Probes inside the plasmasphere for 25 remnant belt events that occurred between 2012 and 2017 and that are located in the region 2.9Date: Dec-07-2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026509 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026509
More Details
Authors: Smirnov A. G., Kronberg E. A., Latallerie F., Daly P. W., Aseev N. A., et al.
Title: Electron intensity measurements by the Cluster/RAPID/IES instrument in Earth's radiation belts and ring current
Abstract: The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earth's magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high‐energy electrons (<400 keV) and inner‐zone protons (230‐630 keV) in the radiation belts and ring current, the data have been rarely used for inner‐magnetospheric science. The current paper presents two algorithms for background correction. The first algorithm is based on the empirical contamination percentages by both protons and electrons. The second algorithm uses simultaneous proton observations. The efficiencies of these algorithms are demonstrated by comparison of the . . .
Date: 02/2019 Publisher: Space Weather DOI: 10.1029/2018SW001989 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW001989
More Details
Authors: Blum L.W., Artemyev A., Agapitov O., Mourenas D., Boardsen S., et al.
Title: EMIC Wave‐Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere
Abstract: While electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron‐resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower‐energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth's inner magnetosphere. Using wave and plasma parameters directly measured by the Van Allen Probes, we estimate bounce resonance diffusion coefficients for four different events, illustrative of wave and plasma parameters to be encountered in the inner magnetosphere. The range o. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026427 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026427
More Details
Authors: Blum L.W., Artemyev A., Agapitov O., Mourenas D., Boardsen S., et al.
Title: EMIC Wave‐Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere
Abstract: While electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron‐resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower‐energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth's inner magnetosphere. Using wave and plasma parameters directly measured by the Van Allen Probes, we estimate bounce resonance diffusion coefficients for four different events, illustrative of wave and plasma parameters to be encountered in the inner magnetosphere. The range o. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026427 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026427
More Details
Authors: Bingley L., Angelopoulos V, Sibeck D., Zhang X., and Halford A.
Title: The Evolution of a Pitch‐Angle “Bite‐Out” Scattering Signature Caused by EMIC Wave Activity: A Case Study
Abstract: Electromagnetic ion cyclotron (EMIC) waves are understood to be one of the dominant drivers of relativistic electron loss from Earth's radiation belts. Theory predicts that the associated gyroresonant wave‐particle interaction results in a distinct energy‐dependent “bite‐out” signature in the normalized flux distribution of electrons as they are scattered into the loss cone. We identify such signatures along with the responsible EMIC waves captured in situ by the Van Allen Probes on 15–16 February 2017. Using the cold plasma approximation, we predict the pitch‐angle cutoffs for the scattering signature for the captured EMIC wave and find it in good agreement with the observed electron bite‐out scattering signature. Employing the close conjunction between the Van Allen Probe. . .
Date: 06/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026292 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026292
More Details
Authors: Yu Yiqun, ätter Lutz, Jordanova Vania K., Zheng Yihua, Engel Miles, et al.
Title: Initial Results From the GEM Challenge on the Spacecraft Surface Charging Environment
Abstract: Spacecraft surface charging during geomagnetically disturbed times is one of the most important causes of satellite anomalies. Predicting the surface charging environment is one prevalent task of the geospace environment models. Therefore, the Geospace Environment Modeling (GEM) Focus Group “Inner Magnetosphere Cross‐energy/Population Interactions” initiated a community‐wide challenge study to assess the capability of several inner magnetosphere ring current models in determining surface charging environment for the Van Allen Probes orbits during the 17 March 2013 storm event. The integrated electron flux between 10 and 50 keV is used as the metrics. Various skill scores are applied to quantitatively measure the modeling performance against observations. Results indicate that no mo. . .
Date: 02/2019 Publisher: Space Weather DOI: 10.1029/2018SW002031 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002031
More Details
Authors: Stepanova M., Antonova E.E., Moya P.S., Pinto V.A., and Valdivia J.A.
Title: Multisatellite Analysis of Plasma Pressure in the Inner Magnetosphere During the 1 June 2013 Geomagnetic Storm
Abstract: Using data from Defense Meteorological Satellite Program 16–18, National Oceanic and Atmospheric Administration 15–19, and METOP 1–2 satellites, we reconstructed for the first time a two‐dimensional statistical distribution of plasma pressure in the inner magnetosphere during the 1 June 2013 geomagnetic storm with time resolution of 6 hr. Simultaneously, we used the data from Van Allen Probes and Time History of Events and Macroscale Interactions missions to obtain the in situ plasma pressure in the equatorial plane. This allowed us to corroborate that the dipole mapping works reasonably well during the storm time and that variations of plasma pressure are consistent at low and high altitudes; namely, we observed a drastic increase in plasma pressure a few hours before the storm on. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025965 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025965
More Details
Authors: Zhang X.‐J., Mourenas D., Artemyev A. V., Angelopoulos V, Bortnik J, et al.
Title: Nonlinear Electron Interaction With Intense Chorus Waves: Statistics of Occurrence Rates
Abstract: A comprehensive statistical analysis on 8 years of lower‐band chorus wave packets measured by the Van Allen Probes and THEMIS spacecraft is performed to examine whether, when, and where these waves are above the theoretical threshold for nonlinear resonant wave‐particle interaction. We find that ∼5–30% of all chorus waves interact nonlinearly with ∼30‐ to 300‐keV electrons possessing equatorial pitch angles of >40° in the outer radiation belt, especially during disturbed (AE>500 nT) periods with energetic particles associated with injections from the plasma sheet. Such considerable occurrence rates of nonlinear interactions imply that the evolution of energetic electron fluxes should be dominated by nonlinear effects, rather than by quasi‐linear diffusion as commonly assum. . .
Date: 06/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083833 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083833
More Details
Authors: Zhang X.‐J., Mourenas D., Artemyev A. V., Angelopoulos V, Bortnik J, et al.
Title: Nonlinear Electron Interaction With Intense Chorus Waves: Statistics of Occurrence Rates
Abstract: A comprehensive statistical analysis on 8 years of lower‐band chorus wave packets measured by the Van Allen Probes and THEMIS spacecraft is performed to examine whether, when, and where these waves are above the theoretical threshold for nonlinear resonant wave‐particle interaction. We find that ∼5–30% of all chorus waves interact nonlinearly with ∼30‐ to 300‐keV electrons possessing equatorial pitch angles of >40° in the outer radiation belt, especially during disturbed (AE>500 nT) periods with energetic particles associated with injections from the plasma sheet. Such considerable occurrence rates of nonlinear interactions imply that the evolution of energetic electron fluxes should be dominated by nonlinear effects, rather than by quasi‐linear diffusion as commonly assum. . .
Date: 06/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083833 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083833
More Details
Authors: Aseev N.A., and Shprits Y.Y.
Title: Reanalysis of ring current electron phase space densities using Van Allen Probe observations, convection model, and log‐normal Kalman filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting erro. . .
Date: 04/2019 Publisher: Space Weather DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
More Details
Authors: Aseev N. A., and Shprits Y Y
Title: Reanalysis of Ring Current Electron Phase Space Densities Using Van Allen Probe Observations, Convection Model, and Log‐Normal Kalman Filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting . . .
Date: 04/2019 Publisher: Space Weather Pages: 619 - 638 DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
More Details
Authors: Yue Chao, Jun Chae‐Woo, Bortnik Jacob, An Xin, Ma Qianli, et al.
Title: The Relationship Between EMIC Wave Properties and Proton Distributions Based on Van Allen Probes Observations
Abstract: Plasma kinetic theory predicts that sufficiently anisotropic proton distribution will excite electromagnetic ion cyclotron (EMIC) waves, which in turn relax the proton distribution to a marginally stable state creating an upper bound on the relaxed proton anisotropy. Here, using EMIC wave observations and coincident plasma measurements made by Van Allen Probes in the inner magnetosphere, we show that the proton distributions are well constrained by this instability to a marginally stable state. Near the threshold, the probability of EMIC wave occurrence is highest, having left‐handed polarization and observed near the magnetic equator with relatively small wave normal angles, indicating that these waves are locally generated. In addition, EMIC waves are distributed in two magnetic local . . .
Date: 04/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082633 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082633
More Details
Authors: Shen Xiao‐Chen, Li Wen, Ma Qianli, Agapitov Oleksiy, and Nishimura Yukitoshi
Title: Statistical Analysis of Transverse Size of Lower Band Chorus Waves Using Simultaneous Multisatellite Observations
Abstract: Chorus waves are known to accelerate or scatter energetic electrons via quasi‐linear or nonlinear wave‐particle interactions in the Earth's magnetosphere. In this letter, by taking advantage of simultaneous observations of chorus waveforms from at least a pair of probes among Van Allen Probes and/or Time History of Events and Macroscale Interactions during Substorms (THEMIS) missions, we statistically calculate the transverse size of lower band chorus wave elements. The average size of lower band chorus wave element is found to be ~315±32 km over L shells of ~5–6. Furthermore, our results suggest that the scale size of lower band chorus tends to be (1) larger at higher L shells; (2) larger at higher magnetic latitudes, especially on the dayside; and (3) larger in the azimuthal direc. . .
Date: 05/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083118 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083118
More Details
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
More Details
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
More Details
2018
Authors: Allison Hayley J., Horne Richard B, Glauert Sarah A, and Del Zanna Giulio
Title: Determination of the Equatorial Electron Differential Flux From Observations at Low Earth Orbit
Abstract: Variations in the high‐energy relativistic electron flux of the radiation belts depend on transport, acceleration, and loss processes, and importantly on the lower‐energy seed population. However, data on the seed population is limited to a few satellite missions. Here we present a new method that utilizes data from the Medium Energy Proton/Electron Detector on board the low‐altitude Polar Operational Environmental Satellites to retrieve the seed population at a pitch angle of 90°. The integral flux values measured by Medium Energy Proton/Electron Detector relate to a low equatorial pitch angle and were converted to omnidirectional flux using parameters obtained from fitting one or two urn:x-wiley:jgra:media:jgra54628:jgra54628-math-0001 functions to pitch angle distributions given . . .
Date: 11/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025786 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025786
More Details
Authors: Boardsen Scott A., Hospodarsky George B., Min Kyungguk, Averkamp Terrance F., Bounds Scott R., et al.
Title: Determining the wave vector direction of equatorial fast magnetosonic waves
Abstract: We perform polarization analysis of the equatorial fast magnetosonic waves electric field over a 20 minute interval of Van Allen Probes A Waveform Receiver burst mode data. The wave power peaks at harmonics of the proton cyclotron frequency indicating the spacecraft is near or in the source region. The wave vector is inferred from the direction of the major axis of the electric field polarization ellipsoid and the sign of the phase between the longitudinal electric and compressional magnetic field components. We show that wave vector is preferentially in the azimuthal direction as opposed to the radial direction. From Poynting flux analysis one would infer that the wave vector is primarily in the radial direction. We show that the error in the Poynting flux is large ~ 90°. These results s. . .
Date: 07/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078695 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078695
More Details
Authors: Zhang X.-J., Mourenas D., Artemyev A. V., Angelopoulos V, and Thorne R M
Title: Electron flux enhancements at L  = 4.2 observed by Global Positioning System satellites: Relationship with solar wind and geomagnetic activity
Abstract: Determining solar wind and geomagnetic activity parameters most favorable to strong electron flux enhancements is an important step towards forecasting radiation belt dynamics. Using electron flux measurements from Global Positioning System satellites at L = 4.2 in 2009‐2016, we seek statistical relationships between flux enhancements at different energies and solar wind dynamic pressure Pdyn, AE, and Kp, from hundreds of events inside and outside the plasmasphere. Most ⩾1 MeV electron flux enhancements occur during non‐storm (or weak storm) times. Flux enhancements of 4 MeV electrons outside the plasmasphere occur during periods of low Pdyn and high AE. We perform superposed epoch analyses of GPS electron fluxes, along with solar wind and geomagnetic indices, 40 keV electron flu. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025497 Available at: http://doi.wiley.com/10.1029/2018JA025497http://onlinelibrary.wiley.com/wol1/doi/10.1029/2018JA025497/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018JA025497
More Details
Authors: Zhang X.-J., Mourenas D., Artemyev A. V., Angelopoulos V, and Thorne R M
Title: Electron flux enhancements at L  = 4.2 observed by Global Positioning System satellites: Relationship with solar wind and geomagnetic activity
Abstract: Determining solar wind and geomagnetic activity parameters most favorable to strong electron flux enhancements is an important step towards forecasting radiation belt dynamics. Using electron flux measurements from Global Positioning System satellites at L = 4.2 in 2009‐2016, we seek statistical relationships between flux enhancements at different energies and solar wind dynamic pressure Pdyn, AE, and Kp, from hundreds of events inside and outside the plasmasphere. Most ⩾1 MeV electron flux enhancements occur during non‐storm (or weak storm) times. Flux enhancements of 4 MeV electrons outside the plasmasphere occur during periods of low Pdyn and high AE. We perform superposed epoch analyses of GPS electron fluxes, along with solar wind and geomagnetic indices, 40 keV electron flu. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025497 Available at: http://doi.wiley.com/10.1029/2018JA025497http://onlinelibrary.wiley.com/wol1/doi/10.1029/2018JA025497/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018JA025497
More Details
Authors: Mourenas D., Zhang X.-J., Artemyev A. V., Angelopoulos V, Thorne R M, et al.
Title: Electron nonlinear resonant interaction with short and intense parallel chorus wave-packets
Abstract: One of the major drivers of radiation belt dynamics, electron resonant interaction with whistler‐mode chorus waves, is traditionally described using the quasi‐linear diffusion approximation. Such a description satisfactorily explains many observed phenomena, but its applicability can be justified only for sufficiently low intensity, long duration waves. Recent spacecraft observations of a large number of very intense lower band chorus waves (with magnetic field amplitudes sometimes reaching ∼1% of the background) therefore challenge this traditional description, and call for an alternative approach when addressing the global, long‐term effects of the nonlinear interaction of these waves with radiation belt electrons. In this paper, we first use observations from the Van Allen Probe. . .
Date: 05/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025417 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025417
More Details
Authors: Mourenas D., Zhang X.-J., Artemyev A. V., Angelopoulos V, Thorne R M, et al.
Title: Electron nonlinear resonant interaction with short and intense parallel chorus wave-packets
Abstract: One of the major drivers of radiation belt dynamics, electron resonant interaction with whistler‐mode chorus waves, is traditionally described using the quasi‐linear diffusion approximation. Such a description satisfactorily explains many observed phenomena, but its applicability can be justified only for sufficiently low intensity, long duration waves. Recent spacecraft observations of a large number of very intense lower band chorus waves (with magnetic field amplitudes sometimes reaching ∼1% of the background) therefore challenge this traditional description, and call for an alternative approach when addressing the global, long‐term effects of the nonlinear interaction of these waves with radiation belt electrons. In this paper, we first use observations from the Van Allen Probe. . .
Date: 05/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025417 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025417
More Details
Authors: Engebretson M. J., Posch J. L., Braun D. J., Li W, Ma Q, et al.
Title: EMIC wave events during the four GEM QARBM challenge intervals
Abstract: This paper presents observations of EMIC waves from multiple data sources during the four GEM challenge events in 2013 selected by the GEM “Quantitative Assessment of Radiation Belt Modeling” focus group: March 17‐18 (Stormtime Enhancement), May 31‐June 2 (Stormtime Dropout), September 19‐20 (Non‐storm Enhancement), and September 23‐25 (Non‐storm Dropout). Observations include EMIC wave data from the Van Allen Probes, GOES, and THEMIS spacecraft in the near‐equatorial magnetosphere and from several arrays of ground‐based search coil magnetometers worldwide, as well as localized ring current proton precipitation data from low‐altitude POES spacecraft. Each of these data sets provides only limited spatial coverage, but their combination shows consistent occurrence patte. . .
Date: 07/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025505 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025505
More Details
Authors: Vainchtein D., Zhang X.-J., Artemyev A. V., Mourenas D., Angelopoulos V, et al.
Title: Evolution of electron distribution driven by nonlinear resonances with intense field-aligned chorus waves
Abstract: Resonant electron interaction with whistler‐mode chorus waves is recognized as one of the main drivers of radiation belt dynamics. For moderate wave intensity, this interaction is well described by quasi‐linear theory. However, recent statistics of parallel propagating chorus waves have demonstrated that 5 − 20% of the observed waves are sufficiently intense to interact nonlinearly with electrons. Such interactions include phase trapping and phase bunching (nonlinear scattering) effects not described by quasi‐linear diffusion. For sufficiently long (large) wave‐packets, these nonlinear effects can result in very rapid electron acceleration and scattering. In this paper we introduce a method to include trapping and nonlinear scattering into the kinetic equation describing the . . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025654 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025654
More Details
Authors: Vainchtein D., Zhang X.-J., Artemyev A. V., Mourenas D., Angelopoulos V, et al.
Title: Evolution of electron distribution driven by nonlinear resonances with intense field-aligned chorus waves
Abstract: Resonant electron interaction with whistler‐mode chorus waves is recognized as one of the main drivers of radiation belt dynamics. For moderate wave intensity, this interaction is well described by quasi‐linear theory. However, recent statistics of parallel propagating chorus waves have demonstrated that 5 − 20% of the observed waves are sufficiently intense to interact nonlinearly with electrons. Such interactions include phase trapping and phase bunching (nonlinear scattering) effects not described by quasi‐linear diffusion. For sufficiently long (large) wave‐packets, these nonlinear effects can result in very rapid electron acceleration and scattering. In this paper we introduce a method to include trapping and nonlinear scattering into the kinetic equation describing the . . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025654 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025654
More Details
Authors: Jaynes A. N., Ali A. F., Elkington S R, Malaspina D. M., Baker D N, et al.
Title: Fast diffusion of ultra-relativistic electrons in the outer radiation belt: 17 March 2015 storm event
Abstract: Inward radial diffusion driven by ULF waves has long been known to be capable of accelerating radiation belt electrons to very high energies within the heart of the belts, but more recent work has shown that radial diffusion values can be highly event‐specific and mean values or empirical models may not capture the full significance of radial diffusion to acceleration events. Here we present an event of fast inward radial diffusion, occurring during a period following the geomagnetic storm of 17 March 2015. Ultra‐relativistic electrons up to ∼8 MeV are accelerated in the absence of intense higher‐frequency plasma waves, indicating an acceleration event in the core of the outer belt driven primarily or entirely by ULF wave‐driven diffusion. We examine this fast diffusion rate alon. . .
Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079786 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079786
More Details
Authors: Shi R., Mourenas D., Artemyev A., Li W, and Ma Q
Title: Highly Oblique Lower-Band Chorus Statistics: Dependencies of Wave Power on Refractive Index and Geomagnetic Activity
Abstract: We use 3 years of Van Allen Probes observations of highly oblique lower‐band chorus waves at low latitudes over L = 4–6 to provide a comprehensive statistics of the distribution of their magnetic and electric powers and full energy density as a function of wave refractive index N, L shell, and geomagnetic activity AE. We use the refractive index calculated either in the cold plasma approximation or in the quasi‐electrostatic (hot plasma) approximation and either observed wave electric fields or corrected wave electric fields accounting for the formation of a plasma sheath around antenna probes in a low‐density plasma. Approximate fits to the maximum refractive index and to the magnetic wave power profile of highly oblique waves are provided as a function of AE and L. Such fits shou. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025337 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025337
More Details
Authors: áhlava J., ěmec F., ík O., šová I., Hospodarskyy G. B., et al.
Title: Longitudinal dependence of whistler mode electromagnetic waves in the Earth's inner magnetosphere
Abstract: We use the measurements performed by the DEMETER (2004‐2010) and the Van Allen Probes (2012‐2016, still operating) spacecraft to investigate the longitudinal dependence of the intensity of whistler mode waves in the Earth's inner magnetosphere. We show that a significant longitudinal dependence is observed inside the plasmasphere on the nightside, primarily in the frequency range 400 Hz–2 kHz. On the other hand, almost no longitudinal dependence is observed on the dayside. The obtained results are compared to the lightning occurrence rate provided by the OTD/LIS mission normalized by a factor accounting for the ionospheric attenuation. The agreement between the two dependencies indicates that lightning generated electromagnetic waves may be responsible for the observed effect, thus s. . .
Date: 07/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025284 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025284
More Details
Authors: Engebretson M. J., Posch J. L., Capman N. S. S., Campuzano N. G., ělik P., et al.
Title: MMS, Van Allen Probes, GOES 13, and Ground Based Magnetometer Observations of EMIC Wave Events Before, During, and After a Modest Interplanetary Shock
Abstract: The stimulation of EMIC waves by a magnetospheric compression is perhaps the closest thing to a controlled experiment that is currently possible in magnetospheric physics, in that one prominent factor that can increase wave growth acts at a well‐defined time. We present a detailed analysis of EMIC waves observed in the outer dayside magnetosphere by the four Magnetosphere Multiscale (MMS) spacecraft, Van Allen Probe A, and GOES 13, and by four very high latitude ground magnetometer stations in the western hemisphere before, during, and after a modest interplanetary shock on December 14, 2015. Analysis shows several features consistent with current theory, as well as some unexpected features. During the most intense MMS wave burst, which began ~ 1 min after the end of a brief magnetosheat. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025984 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025984
More Details
Authors: Engebretson M. J., Posch J. L., Capman N. S. S., Campuzano N. G., ělik P., et al.
Title: MMS, Van Allen Probes, GOES 13, and Ground Based Magnetometer Observations of EMIC Wave Events Before, During, and After a Modest Interplanetary Shock
Abstract: The stimulation of EMIC waves by a magnetospheric compression is perhaps the closest thing to a controlled experiment that is currently possible in magnetospheric physics, in that one prominent factor that can increase wave growth acts at a well‐defined time. We present a detailed analysis of EMIC waves observed in the outer dayside magnetosphere by the four Magnetosphere Multiscale (MMS) spacecraft, Van Allen Probe A, and GOES 13, and by four very high latitude ground magnetometer stations in the western hemisphere before, during, and after a modest interplanetary shock on December 14, 2015. Analysis shows several features consistent with current theory, as well as some unexpected features. During the most intense MMS wave burst, which began ~ 1 min after the end of a brief magnetosheat. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025984 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025984
More Details
Authors: Engebretson M. J., Posch J. L., Capman N. S. S., Campuzano N. G., ělik P., et al.
Title: MMS, Van Allen Probes, GOES 13, and Ground Based Magnetometer Observations of EMIC Wave Events Before, During, and After a Modest Interplanetary Shock
Abstract: The stimulation of EMIC waves by a magnetospheric compression is perhaps the closest thing to a controlled experiment that is currently possible in magnetospheric physics, in that one prominent factor that can increase wave growth acts at a well‐defined time. We present a detailed analysis of EMIC waves observed in the outer dayside magnetosphere by the four Magnetosphere Multiscale (MMS) spacecraft, Van Allen Probe A, and GOES 13, and by four very high latitude ground magnetometer stations in the western hemisphere before, during, and after a modest interplanetary shock on December 14, 2015. Analysis shows several features consistent with current theory, as well as some unexpected features. During the most intense MMS wave burst, which began ~ 1 min after the end of a brief magnetosheat. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025984 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025984
More Details
Authors: Agapitov O., Drake J. F., Vasko I., Mozer F S, Artemyev A., et al.
Title: Nonlinear Electrostatic Steepening of Whistler Waves: The Guiding Factors and Dynamics in Inhomogeneous Systems
Abstract: Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The efficiency of wave‐particle resonant interactions is defined by whistler wave properties which have been described by the approximation of plane linear waves propagating through the cold plasma of the inner magnetosphere. However, recent observations of extremely high‐amplitude whistlers suggest the importance of nonlinear wave‐particle interactions for the dynamics of the outer radiation belt. Oblique chorus waves observed in the inner magnetosphere often exhibit drastically nonsinusoidal (with significant power in the higher harmonics) waveforms of the parallel electric field, pres. . .
Date: 03/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076957 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017GL076957
More Details
Authors: Agapitov O., Drake J. F., Vasko I., Mozer F S, Artemyev A., et al.
Title: Nonlinear Electrostatic Steepening of Whistler Waves: The Guiding Factors and Dynamics in Inhomogeneous Systems
Abstract: Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The efficiency of wave‐particle resonant interactions is defined by whistler wave properties which have been described by the approximation of plane linear waves propagating through the cold plasma of the inner magnetosphere. However, recent observations of extremely high‐amplitude whistlers suggest the importance of nonlinear wave‐particle interactions for the dynamics of the outer radiation belt. Oblique chorus waves observed in the inner magnetosphere often exhibit drastically nonsinusoidal (with significant power in the higher harmonics) waveforms of the parallel electric field, pres. . .
Date: 03/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076957 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017GL076957
More Details
Authors: Agapitov O., Drake J. F., Vasko I., Mozer F S, Artemyev A., et al.
Title: Nonlinear Electrostatic Steepening of Whistler Waves: The Guiding Factors and Dynamics in Inhomogeneous Systems
Abstract: Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The efficiency of wave‐particle resonant interactions is defined by whistler wave properties which have been described by the approximation of plane linear waves propagating through the cold plasma of the inner magnetosphere. However, recent observations of extremely high‐amplitude whistlers suggest the importance of nonlinear wave‐particle interactions for the dynamics of the outer radiation belt. Oblique chorus waves observed in the inner magnetosphere often exhibit drastically nonsinusoidal (with significant power in the higher harmonics) waveforms of the parallel electric field, pres. . .
Date: 03/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076957 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017GL076957
More Details
Authors: Artemyev A. V., Zhang X.-J., Angelopoulos V, Runov A., Spence H E, et al.
Title: Plasma anisotropies and currents in the near-Earth plasma sheet and inner magnetosphere
Abstract: The region occupying radial distances of ∼3 − 9 Earth radii (RE) in the night side, includes the near‐Earth plasma sheet with stretched magnetic field lines and the inner magnetosphere with strong dipolar magnetic field. In this region, the plasma flow energy, which was injected into the inner magnetosphere from the magnetotail, is converted to particle heating and electromagnetic wave generation. These important processes are controlled by plasma anisotropies, which are the focus of this study. Using measurements of THEMIS and Van Allen Probes in this transition region we obtain radial profiles of ion and electron temperatures and anisotropies for various geomagnetic activity levels. Ion and electron anisotropies vary with the geomagnetic activity in opposite directions. Paralle. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025232 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025232
More Details
Authors: Artemyev A. V., Zhang X.-J., Angelopoulos V, Runov A., Spence H E, et al.
Title: Plasma anisotropies and currents in the near-Earth plasma sheet and inner magnetosphere
Abstract: The region occupying radial distances of ∼3 − 9 Earth radii (RE) in the night side, includes the near‐Earth plasma sheet with stretched magnetic field lines and the inner magnetosphere with strong dipolar magnetic field. In this region, the plasma flow energy, which was injected into the inner magnetosphere from the magnetotail, is converted to particle heating and electromagnetic wave generation. These important processes are controlled by plasma anisotropies, which are the focus of this study. Using measurements of THEMIS and Van Allen Probes in this transition region we obtain radial profiles of ion and electron temperatures and anisotropies for various geomagnetic activity levels. Ion and electron anisotropies vary with the geomagnetic activity in opposite directions. Paralle. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025232 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025232
More Details
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
More Details
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
More Details
2017
Authors: Souza V. M., Lopez R. E., Jauer P. R., Sibeck D G, Pham K., et al.
Title: Acceleration of radiation belt electrons and the role of the average interplanetary magnetic field B z component in high speed streams
Abstract: In this study we examine the recovery of relativistic radiation belt electrons on November 15-16, 2014, after a previous reduction in the electron flux resulting from the passage of a Corotating Interaction Region (CIR). Following the CIR, there was a period of high-speed streams characterized by large, nonlinear fluctuations in the interplanetary magnetic field (IMF) components. However, the outer radiation belt electron flux remained at a low level for several days before it increased in two major steps. The first increase is associated with the IMF background field turning from slightly northward on average, to slightly southward on average. The second major increase is associated with an increase in the solar wind velocity during a period of southward average IMF background field. We p. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024187 Available at: onlinelibrary.wiley.com/doi/10.1002/2017JA024187/full
More Details
Authors: Yue Chao, Bortnik Jacob, Thorne Richard M, Ma Qianli, An Xin, et al.
Title: The characteristic pitch angle distributions of 1 eV to 600 keV protons near the equator based on Van Allen Probes observations
Abstract: Understanding the source and loss processes of various plasma populations is greatly aided by having accurate knowledge of their pitch angle distributions (PADs). Here, we statistically analyze ~1 eV to 600 keV hydrogen (H+) PADs near the geomagnetic equator in the inner magnetosphere based on Van Allen Probes measurements, to comprehensively investigate how the H+ PADs vary with different energies, magnetic local times (MLTs), L-shells, and geomagnetic conditions. Our survey clearly indicates four distinct populations with different PADs: (1) a pancake distribution of the plasmaspheric H+ at low L-shells except for dawn sector; (2) a bi-directional field-aligned distribution of the warm plasma cloak; (3) pancake or isotropic distributions of ring current H+; (4) radiation belt particles s. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024421 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024421/full
More Details
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
More Details
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
More Details
Authors: Li Jinxing, Bortnik Jacob, An Xin, Li Wen, Thorne Richard M, et al.
Title: Chorus Wave Modulation of Langmuir Waves in the Radiation Belts
Abstract: Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E|| component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity that matches the parallel phase velocity of the chorus waves. Based on this evidence, we conclude that the chorus waves accelerate the suprathermal electrons via Landau resonance and generate a localized electron beam in phase space density. Consequently, the Langmuir wave. . .
Date: 12/2017 Publisher: Geophysical Research Letters Pages: 11,713 - 11,721 DOI: 10.1002/2017GL075877 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017GL075877/full
More Details
Authors: Agapitov O., Blum L. W., Mozer F S, Bonnell J. W., and Wygant J
Title: Chorus whistler wave source scales as determined from multipoint Van Allen Probe measurements
Abstract: Whistler mode chorus waves are particularly important in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The key parameters for both nonlinear and quasi-linear treatment of wave-particle interactions are the temporal and spatial scales of the wave source region and coherence of the wave field perturbations. Neither the source scale nor the coherence scale is well established experimentally, mostly because of a lack of multipoint VLF waveform measurements. We present an unprecedentedly long interval of coordinated VLF waveform measurements (sampled at 16384 s−1) aboard the two Van Allen Probes spacecraft—9 h (0800–1200 UT and 1700–2200 UT) during two consecutive apogees on 15 July . . .
Date: 03/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL072701 Available at: http://doi.wiley.com/10.1002/2017GL072701
More Details
Authors: Aryan Homayon, Sibeck David G., Bin Kang Suk-, Balikhin Michael A., Fok Mei-Ching, et al.
Title: CIMI simulations with newly developed multi-parameter chorus and plasmaspheric hiss wave models
Abstract: Numerical simulation studies of the Earth's radiation belts are important to understand the acceleration and loss of energetic electrons. The Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model considers the effects of the ring current and plasmasphere on the radiation belts to obtain plausible results. The CIMI model incorporates pitch angle, energy, and cross diffusion of electrons, due to chorus and plasmaspheric hiss waves. These parameters are calculated using statistical wave distribution models of chorus and plasmaspheric hiss amplitudes. However, currently these wave distribution models are based only on a single parameter, geomagnetic index (AE), and could potentially underestimate the wave amplitudes. Here we incorporate recently developed multi-parameter chorus and plasmas. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024159 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024351/full
More Details
Authors: Aryan Homayon, Sibeck David G., Bin Kang Suk-, Balikhin Michael A., Fok Mei-Ching, et al.
Title: CIMI simulations with newly developed multi-parameter chorus and plasmaspheric hiss wave models
Abstract: Numerical simulation studies of the Earth's radiation belts are important to understand the acceleration and loss of energetic electrons. The Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model considers the effects of the ring current and plasmasphere on the radiation belts to obtain plausible results. The CIMI model incorporates pitch angle, energy, and cross diffusion of electrons, due to chorus and plasmaspheric hiss waves. These parameters are calculated using statistical wave distribution models of chorus and plasmaspheric hiss amplitudes. However, currently these wave distribution models are based only on a single parameter, geomagnetic index (AE), and could potentially underestimate the wave amplitudes. Here we incorporate recently developed multi-parameter chorus and plasmas. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024159 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024351/full
More Details
Authors: Zhang X.-J., Mourenas D., Artemyev A. V., Angelopoulos V, and Thorne R M
Title: Contemporaneous EMIC and Whistler-Mode Waves: Observations and Consequences for MeV Electron Loss
Abstract: The high variability of relativistic (MeV) electron fluxes in the Earth's radiation belts is partly controlled by loss processes involving resonant interactions with electromagnetic ion cyclotron (EMIC) and whistler-mode waves. But as previous statistical models were generated independently for each wave mode, whether simultaneous electron scattering by the two wave types has global importance remains an open question. Using >3 years of simultaneous Van Allen Probes and THEMIS measurements, we explore the contemporaneous presence of EMIC and whistler-mode waves in the same L-shell, albeit at different local times, determining the distribution of wave and plasma parameters as a function of L, Kp, and AE. We derive electron lifetimes from observations and provide the first statistics of comb. . .
Date: 07/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL073886 Available at: onlinelibrary.wiley.com/doi/10.1002/2017GL073886/full
More Details
Authors: Zhang X.-J., Mourenas D., Artemyev A. V., Angelopoulos V, and Thorne R M
Title: Contemporaneous EMIC and Whistler-Mode Waves: Observations and Consequences for MeV Electron Loss
Abstract: The high variability of relativistic (MeV) electron fluxes in the Earth's radiation belts is partly controlled by loss processes involving resonant interactions with electromagnetic ion cyclotron (EMIC) and whistler-mode waves. But as previous statistical models were generated independently for each wave mode, whether simultaneous electron scattering by the two wave types has global importance remains an open question. Using >3 years of simultaneous Van Allen Probes and THEMIS measurements, we explore the contemporaneous presence of EMIC and whistler-mode waves in the same L-shell, albeit at different local times, determining the distribution of wave and plasma parameters as a function of L, Kp, and AE. We derive electron lifetimes from observations and provide the first statistics of comb. . .
Date: 07/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL073886 Available at: onlinelibrary.wiley.com/doi/10.1002/2017GL073886/full
More Details

Pages