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2D particle‐in‐cell simulation
Authors: Min Kyungguk, Boardsen Scott A., Denton Richard E, and Liu Kaijun
Title: Equatorial Evolution of the Fast Magnetosonic Mode in the Source Region: Observation-Simulation Comparison of the Preferential Propagation Direction
Abstract: Recent analysis of an event observed by the Van Allen Probes in the source region outside the plasmapause has shown that fast magnetosonic waves (also referred to as equatorial noise) propagate preferentially in the azimuthal direction, implying that wave amplification should occur during azimuthal propagation. To demonstrate this, we carry out 2‐D particle‐in‐cell simulations of the fast magnetosonic mode at the dipole magnetic equator with the simulation box size, the magnetic field inhomogeneity, and the plasma parameters chosen from the same event recently analyzed. The self‐consistently evolving electric and magnetic field fluctuations are characterized by spectral peaks at harmonics of the local proton cyclotron frequency. The azimuthal component of the electric field fluctua. . .
Date: 11/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026037 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026037
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Acceleration
Authors: Reeves Geoffrey D, Friedel Reiner H W, Larsen Brian A., Skoug Ruth M., Funsten Herbert O., et al.
Title: Energy dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions.
Abstract: We present observations of the radiation belts from the HOPE and MagEIS particle detectors on the Van Allen Probes satellites that illustrate the energy-dependence and L-shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on March 1 in more detail. The observations show: (a) At all L-shells, lower-energy electrons are enhanced more often than higher energies; (b) Events that fill the slot region are more common at lower energies; (c) Enhancements of electrons in the inner zone are more common at lower energies; and (d) Even when events do not fully fill the slot region, enhancements at lower-energies tend to extend to lower L-shells than higher energies. During enhancement events the outer zone extends to lower L-shells at lower energie. . .
Date: 12/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021569 Available at: http://doi.wiley.com/10.1002/2015JA021569http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021569
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Authors: Kronberg E. A., Grigorenko E. E., Turner D. L., Daly P. W., Khotyaintsev Y., et al.
Title: Comparing and contrasting dispersionless injections at geosynchronous orbit during a substorm event
Abstract: Particle injections in the magnetosphere transport electrons and ions from the magnetotail to the radiation belts. Here we consider generation mechanisms of “dispersionless” injections, namely, those with simultaneous increase of the particle flux over a wide energy range. In this study we take advantage of multisatellite observations which simultaneously monitor Earth's magnetospheric dynamics from the tail toward the radiation belts during a substorm event. Dispersionless injections are associated with instabilities in the plasma sheet during the growth phase of the substorm, with a dipolarization front at the onset and with magnetic flux pileup during the expansion phase. They show different spatial spread and propagation characteristics. Injection associated with the dipolarization. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023551 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023551/full
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adiabatic electron transport
Authors: Degeling A W, Rankin R, and Zong Q.-G.
Title: Modeling radiation belt electron acceleration by ULF fast mode waves, launched by solar wind dynamic pressure fluctuations
Abstract: We investigate the magnetospheric MHD and energetic electron response to a Storm Sudden Commencement (SSC) and subsequent magnetopause buffeting, focusing on an interval following an SSC event on 25 November 2001. We find that the electron flux signatures observed by LANL, Cluster, and GOES spacecraft during this event can largely be reproduced using an advective kinetic model for electron phase space density, using externally prescribed electromagnetic field inputs, (herein described as a “test-kinetic model”) with electromagnetic field inputs provided by a 2-D linear ideal MHD model for ULF waves. In particular, we find modulations in electron flux phase shifted by 90° from the local azimuthal ULF wave electric field (Eφ) and a net enhancement in electron flux after 1.5 h for energ. . .
Date: 11/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2013JA019672 Available at: http://doi.wiley.com/10.1002/2013JA019672
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alfvén fluctuations
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
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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
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Alfven waves
Authors: Damiano P.A., Chaston C.C., Hull A.J., and Johnson J.R.
Title: Electron Distributions in Kinetic Scale Field Line Resonances: A Comparison of Simulations and Observations
Abstract: Observations in kinetic scale field line resonances, or eigenmodes of the geomagnetic field, reveal highly field‐aligned plateaued electron distributions. By combining observations from the Van Allen Probes and Cluster spacecraft with a hybrid kinetic gyrofluid simulation we show how these distributions arise from the nonlocal self‐consistent interaction of electrons with the wavefield. This interaction is manifested as electron trapping in the standing wave potential. The process operates along most of the field line and qualitatively accounts for electron observations near the equatorial plane and at higher latitudes. In conjunction with the highly field‐aligned plateaus, loss cone features are also evident, which result from the action of the upward‐directed wave parallel electr. . .
Date: 06/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL077748 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077748
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artificial satellites
Authors: Nag Sreeja, LeMoigne Jacqueline, and de Weck Olivier
Title: Cost and risk analysis of small satellite constellations for earth observation
Abstract: Distributed Space Missions (DSMs) are gaining momentum in their application to Earth science missions owing to their ability to increase observation sampling in spatial, spectral, temporal and angular dimensions. Past literature from academia and industry have proposed and evaluated many cost models for spacecraft as well as methods for quantifying risk. However, there have been few comprehensive studies quantifying the cost for multiple spacecraft, for small satellites and the cost risk for the operations phase of the project which needs to be budgeted for when designing and building efficient architectures. This paper identifies the three critical problems with the applicability of current cost and risk models to distributed small satellite missions and uses data-based modeling to sugges. . .
Date: 03/2014 Publisher: IEEE DOI: 10.1109/AERO.2014.6836396 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6836396
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Astrophysical plasmas
Authors: Mann I. R., Ozeke L. G., Murphy K. R., Claudepierre S G, Turner D. L., et al.
Title: Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt
Abstract: Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a datadriven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence o. . .
Date: 06/2016 Publisher: Nature Physics DOI: 10.1038/nphys3799 Available at: http://www.nature.com/doifinder/10.1038/nphys3799
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Authors: Mann I. R., Ozeke L. G., Murphy K. R., Claudepierre S G, Turner D. L., et al.
Title: Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt
Abstract: Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a datadriven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence o. . .
Date: 06/2016 Publisher: Nature Physics DOI: 10.1038/nphys3799 Available at: http://www.nature.com/doifinder/10.1038/nphys3799
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aurora
Authors: Lyons L R, Nishimura Y., Gallardo-Lacourt B., Nicolls M. J., Chen S., et al.
Title: Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts
Abstract: We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds varying from ~100 m/s to ~1 km/s in just a few minutes. The auroral brightenings are associated with bursts of weak electron precipitation that move westward with the westward flow bursts and extend into the SAPS region. Additionally, our observations show evidence that the. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021023 Available at: http://doi.wiley.com/10.1002/2015JA021023
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Authors: Jaynes A. N., Lessard M. R., Takahashi K., Ali A. F., Malaspina D. M., et al.
Title: Correlated Pc4-5 ULF waves, whistler-mode chorus and pulsating aurora observed by the Van Allen Probes and ground-based systems
Abstract: Theory and observations have linked equatorial VLF waves with pulsating aurora for decades, invoking the process of pitch-angle scattering of 10's keV electrons in the equatorial magnetosphere. Recently published satellite studies have strengthened this argument, by showing strong correlation between pulsating auroral patches and both lower-band chorus and 10's keV electron modulation in the vicinity of geosynchronous orbit. Additionally, a previous link has been made between Pc4-5 compressional pulsations and modulation of whistler-mode chorus using THEMIS. In the current study, we present simultaneous in-situ observations of structured chorus waves and an apparent field line resonance (in the Pc4-5 range) as a result of a substorm injection, observed by Van Allen Probes, along with groun. . .
Date: 07/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021380 Available at: http://doi.wiley.com/10.1002/2015JA021380
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banded chorus
Authors: Fu Xiangrong, Guo Zehua, Dong Chuanfei, and Gary Peter
Title: Nonlinear subcyclotron resonance as a formationmechanism for gaps in banded chorus
Abstract: An interesting characteristic of magnetospheric chorus is the presence of a frequency gap at ω≃0.5Ωe, where Ωe is the electron cyclotron angular frequency. Recent chorus observations sometimes show additional gaps near 0.3Ωe and 0.6Ωe. Here we present a novel nonlinear mechanism for the formation of these gaps using Hamiltonian theory and test particle simulations in a homogeneous, magnetized, collisionless plasma. We find that an oblique whistler wave with frequency at a fraction of the electron cyclotron frequency can resonate with electrons, leading to effective energy exchange between the wave and particles.
Date: 05/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064182 Available at: http://doi.wiley.com/10.1002/2015GL064182
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Bernstein mode instability
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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bounce resonance
Authors: Chen Lunjin, Maldonado Armando, Bortnik Jacob, Thorne Richard M, Li Jinxing, et al.
Title: Nonlinear Bounce Resonances between Magnetosonic Waves and Equatorially Mirroring Electrons
Abstract: Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the fluxof these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from a equatorial pitch angle of 90 degrees down to lower values. However this mechanism has not been uniquely identified yet. Here, we investigate the mechanism of bounce resonance with equatorial noise (or fast magnetosonic waves). A test particle simulation is used to examine the effects of monochromatic magnetosonic waves on the equatorially mirroring energetic electrons, with a special. . .
Date: 06/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021174 Available at: http://doi.wiley.com/10.1002/2015JA021174
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bump-on-tail
Authors: Wei Chao, Dai Lei, Duan Suping, Wang Chi, Wang YuXian, et al.
Title: Multiple satellites observation evidence: High-m Poloidal ULF waves with time-varying polarization states
Abstract: We report multi‐spacecraft observations of ULF waves from Van Allen Probes (RBSP), Magnetospheric Multiscale (MMS), Time History of Events and Macroscale Interactions during Substorm (THEMIS), and Geostationary Operational Environmental Satellites (GOES). On August 31, 2015, global‐scale poloidal waves were observed in data from RBSP‐B, GOES and THEMIS from L=4 to L=8 over a wide range of magnetic local time (MLT). The polarization states varied towards purely poloidal polarity. In two consecutive orbits over 18 hours, RBSP‐A and RBSP‐B recorded gradual variation of the polarization states of the poloidal waves; the ratio (|Ba|/|Br|) decreased from 0.82 to 0.13. After the variation of polarization states, the poloidal ULF waves became very purely poloidal waves, localized in both. . .
Date: 05/2019 Publisher: Earth and Planetary Physics Pages: 190 - 203 DOI: 10.26464/epp2019021 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.26464/epp2019021
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Authors: Wei Chao, Dai Lei, Duan Suping, Wang Chi, Wang YuXian, et al.
Title: Multiple satellites observation evidence: High-m Poloidal ULF waves with time-varying polarization states
Abstract: We report multi‐spacecraft observations of ULF waves from Van Allen Probes (RBSP), Magnetospheric Multiscale (MMS), Time History of Events and Macroscale Interactions during Substorm (THEMIS), and Geostationary Operational Environmental Satellites (GOES). On August 31, 2015, global‐scale poloidal waves were observed in data from RBSP‐B, GOES and THEMIS from L=4 to L=8 over a wide range of magnetic local time (MLT). The polarization states varied towards purely poloidal polarity. In two consecutive orbits over 18 hours, RBSP‐A and RBSP‐B recorded gradual variation of the polarization states of the poloidal waves; the ratio (|Ba|/|Br|) decreased from 0.82 to 0.13. After the variation of polarization states, the poloidal ULF waves became very purely poloidal waves, localized in both. . .
Date: 05/2019 Publisher: Earth and Planetary Physics Pages: 190 - 203 DOI: 10.26464/epp2019021 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.26464/epp2019021
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chorus modulation
Authors: Xia Zhiyang, Chen Lunjin, Dai Lei, Claudepierre Seth G., Chan Anthony A, et al.
Title: Modulation of chorus intensity by ULF waves deep in the inner magnetosphere
Abstract: Previous studies have shown that chorus wave intensity can be modulated by Pc4-Pc5 compressional ULF waves. In this study, we present Van Allen Probes observation of ULF wave modulating chorus wave intensity, which occurred deep in the magnetosphere. The ULF wave shows fundamental poloidal mode signature and mirror mode compressional nature. The observed ULF wave can modulate not only the chorus wave intensity but also the distribution of both protons and electrons. Linear growth rate analysis shows consistence with observed chorus intensity variation at low frequency (f <∼ 0.3fce), but cannot account for the observed higher-frequency chorus waves, including the upper band chorus waves. This suggests the chorus waves at higher-frequency ranges require nonlinear mechanisms. In addition, w. . .
Date: 09/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL070280 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2016GL070280/full
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chorus waves
Authors: Hartley D. P., Chen Y., Kletzing C A, Denton M. H., and Kurth W S
Title: Applying the cold plasma dispersion relation to whistler mode chorus waves: EMFISIS wave measurements from the Van Allen Probes
Abstract: Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus wave band (0.1–0.9 fce). Results from this study indicate that the calculated wave intensity is least accurate during periods of enhanced wave activity. For observed wave intensities >10−3 nT2, using the cold plasma dispersi. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020808 Available at: http://doi.wiley.com/10.1002/2014JA020808
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Chorus-type whistler waves
Authors: Breuillard H., Agapitov O., Artemyev A., Kronberg E. A., Haaland S. E., et al.
Title: Field-aligned chorus wave spectral power in Earth's outer radiation belt
Abstract: Chorus-type whistler waves are one of the most intense electromagnetic waves generated naturally in the magnetosphere. These waves have a substantial impact on the radiation belt dynamics as they are thought to contribute to electron acceleration and losses into the ionosphere through resonant wave–particle interaction. Our study is devoted to the determination of chorus wave power distribution on frequency in a wide range of magnetic latitudes, from 0 to 40°. We use 10 years of magnetic and electric field wave power measured by STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus wave spectral power, as well as PEACE and RAPID measurements to model the properties of energetic electrons (~ 0.1–100 keV) in the outer radiation belt. The dependence of this distrib. . .
Date: 01/2015 Publisher: Annales Geophysicae Pages: 583 - 597 DOI: 10.5194/angeo-33-583-2015 Available at: http://www.ann-geophys.net/33/583/2015/http://www.ann-geophys.net/33/583/2015/angeo-33-583-2015.pdf
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Cluster
Authors: Allen R. C., Zhang J. -C., Kistler L. M., Spence H E, Lin R. -L., et al.
Title: A statistical study of EMIC waves observed by Cluster: 1. Wave properties
Abstract: Electromagnetic ion cyclotron (EMIC) waves are an important mechanism for particle energization and losses inside the magnetosphere. In order to better understand the effects of these waves on particle dynamics, detailed information about the occurrence rate, wave power, ellipticity, normal angle, energy propagation angle distributions, as well as local plasma parameters are required. Previous statistical studies have used in situ observations to investigate the distribution of these parameters in the MLT-L frame within a limited MLAT range. In this study, we present a statistical analysis of EMIC wave properties using ten years (2001–2010) of data from Cluster, totaling 25,431 minutes of wave activity. Due to the polar orbit of Cluster, we are able to investigate EMIC waves at all MLATs. . .
Date: 06/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021333 Available at: http://doi.wiley.com/10.1002/2015JA021333
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convection
Authors: Lyons L R, Nishimura Y., Gallardo-Lacourt B., Nicolls M. J., Chen S., et al.
Title: Azimuthal flow bursts in the Inner Plasma Sheet and Possible Connection with SAPS and Plasma Sheet Earthward Flow Bursts
Abstract: We have combined radar observations and auroral images obtained during the PFISR Ion Neutral Observations in the Thermosphere campaign to show the common occurrence of westward moving, localized auroral brightenings near the auroral equatorward boundary and to show their association with azimuthally moving flow bursts near or within the SAPS region. These results indicate that the SAPS region, rather than consisting of relatively stable proton precipitation and westward flows, can have rapidly varying flows, with speeds varying from ~100 m/s to ~1 km/s in just a few minutes. The auroral brightenings are associated with bursts of weak electron precipitation that move westward with the westward flow bursts and extend into the SAPS region. Additionally, our observations show evidence that the. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021023 Available at: http://doi.wiley.com/10.1002/2015JA021023
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Authors: De Pascuale S., Jordanova V K, Goldstein J, Kletzing C A, Kurth W S, et al.
Title: Simulations of Van Allen Probes Plasmaspheric Electron Density Observations
Abstract: We simulate equatorial plasmaspheric electron densities using a physics‐based model (Cold PLasma, CPL; used in the ring current‐atmosphere interactions model) of the source and loss processes of refilling and erosion driven by empirical inputs. The performance of CPL is evaluated against in situ measurements by the Van Allen Probes (Radiation Belt Storm Probes) for two events: the 31 May to 5 June and 15 to 20 January 2013 geomagnetic storms observed in the premidnight and postmidnight magnetic local time (MLT) sectors, respectively. Overall, CPL reproduces the radial extent of the plasmasphere to within a mean absolute difference of urn:x-wiley:jgra:media:jgra54637:jgra54637-math-0001 L. The model electric field responsible for E × B convection and the parameterization of geomagn. . .
Date: 11/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025776 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025776
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convection electric field
Authors: Thaller S. A., Wygant J R, Cattell C. A., Breneman A. W., Tyler E., et al.
Title: Solar rotation period driven modulations of plasmaspheric density and convective electric field in the inner magnetosphere
Abstract: This paper presents the first analysis of Van Allen Probes measurements of the cold plasma density and electric field in the inner magnetosphere to show that intervals of strong modulation at the solar rotation period occur in the locations of the outer plasmasphere and plasmapause (~0.7 RE peak‐to‐peak), in the large‐scale electric field (~0.24 mV/m peak‐to‐peak), and in the cold plasma density (~250 cm‐3 – ~70 cm‐3 peak‐to‐peak). Solar rotation modulation of the inner magnetosphere is more apparent in the declining phase of the solar cycle than near solar maximum. The periodicities in these parameters are compared to solar EUV irradiance, solar wind dawn‐dusk electric field, and Kp. The variations in the plasmapause location at the solar rotation period anti‐corre. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026365 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026365
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cosmic noise absorption
Authors: Kellerman A. C., Shprits Y Y, Makarevich R. A., Spanswick E., Donovan E., et al.
Title: Characterization of the energy-dependent response of riometer absorption
Abstract: Ground based riometers provide an inexpensive means to continuously remote sense the precipitation of electrons in the dynamic auroral region of Earth's ionosphere. The energy-dependent relationship between riometer absorption and precipitating electrons is thus of great importance for understanding the loss of electrons from the Earth's magnetosphere. In this study, statistical and event-based analyses are applied to determine the energy of electrons to which riometers chiefly respond. Time-lagged correlation analysis of trapped to precipitating fluxes shows that daily averaged absorption best correlates with ~ 60 keV trapped electron flux at zero-time lag, although large variability is observed across different phases of the solar cycle. High-time resolution statistical cross-correlati. . .
Date: 11/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020027 Available at: http://doi.wiley.com/10.1002/2014JA020027
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current wedge
Authors: Kronberg E. A., Grigorenko E. E., Turner D. L., Daly P. W., Khotyaintsev Y., et al.
Title: Comparing and contrasting dispersionless injections at geosynchronous orbit during a substorm event
Abstract: Particle injections in the magnetosphere transport electrons and ions from the magnetotail to the radiation belts. Here we consider generation mechanisms of “dispersionless” injections, namely, those with simultaneous increase of the particle flux over a wide energy range. In this study we take advantage of multisatellite observations which simultaneously monitor Earth's magnetospheric dynamics from the tail toward the radiation belts during a substorm event. Dispersionless injections are associated with instabilities in the plasma sheet during the growth phase of the substorm, with a dipolarization front at the onset and with magnetic flux pileup during the expansion phase. They show different spatial spread and propagation characteristics. Injection associated with the dipolarization. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023551 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023551/full
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Density
Authors: Hartley D. P., Kletzing C A, De Pascuale S., Kurth W S, and ík O.
Title: Determining Plasmaspheric Densities from Observations of Plasmaspheric Hiss
Abstract: A new method of inferring electron plasma densities inside of the plasmasphere is presented. Utilizing observations of the electric and magnetic field wave power associated with plasmaspheric hiss, coupled with the cold plasma dispersion relation, permits calculation of the plasma density. This methodology yields a density estimate for each frequency channel and time interval where plasmaspheric hiss is observed and is shown to yield results that are generally in agreement with densities determined via other methods. A statistical calibration is performed against the density from the upper hybrid line, accounting for both systematic offsets and distribution scatter in the hiss‐inferred densities. This calculation and calibration methodology provides accurate density estimates, both stati. . .
Date: 08/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025658 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025658
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diffusion coefficients
Authors: Zhao Lei, Yu Yiqun, Delzanno Gian Luca, and Jordanova Vania K.
Title: Bounce- and MLT-averaged diffusion coefficients in a physics-based magnetic field geometry obtained from RAM-SCB for the 17 March 2013 storm
Abstract: Local acceleration via whistler wave and particle interaction plays a significant role in particle dynamics in the radiation belt. In this work we explore gyroresonant wave-particle interaction and quasi-linear diffusion in different magnetic field configurations related to the 17 March 2013 storm. We consider the Earth's magnetic dipole field as a reference and compare the results against nondipole field configurations corresponding to quiet and stormy conditions. The latter are obtained with the ring current-atmosphere interactions model with a self-consistent magnetic field (RAM-SCB), a code that models the Earth's ring current and provides a realistic modeling of the Earth's magnetic field. By applying quasi-linear theory, the bounce- and Magnetic Local Time (MLT)-averaged electron pit. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020858 Available at: http://doi.wiley.com/10.1002/2014JA020858
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Authors: Ripoll J.-F., Santol?k O., Reeves G., Kurth W S, Denton M., et al.
Title: Effects of whistler mode hiss waves in March 2013
Abstract: We present simulations of the loss of radiation belt electrons by resonant pitch angle diffusion caused by whistler mode hiss waves for March 2013. Pitch angle diffusion coefficients are computed from the wave properties and the ambient plasma data obtained by the Van Allen Probes with a resolution of 8 hours and 0.1 L-shell. Loss rates follow a complex dynamic structure, imposed by the wave and plasma properties. Hiss effects can be strong, with minimum lifetimes (of ~1 day) moving from energies of ~100 keV at L~5 up to ~2 MeV at L~2, and stop abruptly, similarly to the observed energy-dependent inner belt edge. Periods when the plasmasphere extends beyond L~5 favor long-lasting hiss losses from the outer belt. Such loss rates are embedded in a reduced Fokker-Planck code and validated aga. . .
Date: 06/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024139 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024139/full
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Dipolarization
Authors: Reiff P. H., Daou A. G., Sazykin S. Y., Nakamura R, Hairston M. R., et al.
Title: Multispacecraft Observations and Modeling of the June 22/23, 2015 Geomagnetic Storm
Abstract: The magnetic storm of June 22-23, 2015 was one of the largest in the current solar cycle. We present in situ observations from the Magnetospheric Multiscale Mission (MMS) and the Van Allen Probes (VAP) in the magnetotail, field-aligned currents from AMPERE, and ionospheric flow data from DMSP. Our real-time space weather alert system sent out a “red alert”, correctly predicting Kp indices greater than 8. We show strong outflow of ionospheric Oxygen, dipolarizations in the MMS magnetometer data, and dropouts in the particle fluxes seen by the MMS FPI instrument suite. At ionospheric altitudes, the AMPERE data show highly variable currents exceeding 20 MA. We present numerical simulations with the BATS-R-US global magnetohydrodynamic (MHD) model linked with the Rice Convection Model (RCM. . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL069154 Available at: http://doi.wiley.com/10.1002/2016GL069154
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Authors: Kronberg E. A., Grigorenko E. E., Turner D. L., Daly P. W., Khotyaintsev Y., et al.
Title: Comparing and contrasting dispersionless injections at geosynchronous orbit during a substorm event
Abstract: Particle injections in the magnetosphere transport electrons and ions from the magnetotail to the radiation belts. Here we consider generation mechanisms of “dispersionless” injections, namely, those with simultaneous increase of the particle flux over a wide energy range. In this study we take advantage of multisatellite observations which simultaneously monitor Earth's magnetospheric dynamics from the tail toward the radiation belts during a substorm event. Dispersionless injections are associated with instabilities in the plasma sheet during the growth phase of the substorm, with a dipolarization front at the onset and with magnetic flux pileup during the expansion phase. They show different spatial spread and propagation characteristics. Injection associated with the dipolarization. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023551 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023551/full
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dipolarization front
Authors: Contel O., Nakamura R, Breuillard H., Argall M. R., Graham D. B., et al.
Title: Lower-hybrid drift waves and electromagnetic electron space-phase holes associated with dipolarization fronts and field-aligned currents observed by the Magnetospheric Multiscale mission during a substorm
Abstract: We analyse two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on August 10, 2016. The first event corresponds to a fast dawnward flow with an anti-parallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower-hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing, and with a smaller lower-hybrid drift wave activity. Electromag. . .
Date: 10/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024550 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024550/full
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Authors: Contel O., Nakamura R, Breuillard H., Argall M. R., Graham D. B., et al.
Title: Lower-hybrid drift waves and electromagnetic electron space-phase holes associated with dipolarization fronts and field-aligned currents observed by the Magnetospheric Multiscale mission during a substorm
Abstract: We analyse two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on August 10, 2016. The first event corresponds to a fast dawnward flow with an anti-parallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower-hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing, and with a smaller lower-hybrid drift wave activity. Electromag. . .
Date: 10/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024550 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024550/full
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distribution
Authors: Wang Dedong, Yuan Zhigang, Yu Xiongdong, Deng Xiaohua, Zhou Meng, et al.
Title: Statistical characteristic of EMIC waves: Van Allen Probe observations
Abstract: Utilizing the data from the magnetometer instrument which is a part of the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument suite onboard the Van Allen Probe A from Sep. 2012 to Apr. 2014, when the apogee of the satellite has passed all the MLT sectors, we obtain the statistical distribution characteristic of EMIC waves in the inner magnetosphere over all local times from L=3 to L=6. Compared with the previous statistical results about EMIC waves, the occurrence rates of EMIC waves distribute relatively uniform in the MLT sectors in lower L-shells. On the other hand, in higher L-shells, there are indeed some peaks of the occurrence rate for the EMIC waves, especially in the noon, dusk and night sectors. EMIC waves appear at lower L-shells in the dawn. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021089 Available at: http://doi.wiley.com/10.1002/2015JA021089
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Earth's magnetosphere
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
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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
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Earth's Outer Radiation Belts
Authors: Drake J. F., Agapitov O. V., and Mozer F S
Title: The development of a bursty precipitation front with intense localized parallel electric fields driven by whistler waves
Abstract: The dynamics and structure of whistler turbulence relevant to electron acceleration in the Earth's outer radiation belt is explored with simulations and comparisons with observations. An initial state with an electron temperature anisotropy in a spatially localized domain drives whistlers which scatter electrons. An outward propagating front of whistlers and hot electrons nonlinearly evolves to form regions of intense parallel electric field with structure similar to observations. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.
Date: 03/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL063528 Available at: http://doi.wiley.com/10.1002/2015GL063528
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electric field
Authors: Thaller S. A., Wygant J R, Dai L., Breneman A.W., Kersten K., et al.
Title: Van Allen Probes investigation of the large scale duskward electric field and its role in ring current formation and plasmasphere erosion in the June 1, 2013 storm
Abstract: Using the Van Allen Probes we investigate the enhancement in the large scale duskward convection electric field during the geomagnetic storm (Dst ~ −120 nT) on June 1, 2013 and its role in ring current ion transport and energization, and plasmasphere erosion. During this storm, enhancements of ~1-2 mV/m in the duskward electric field in the co-rotating frame are observed down to L shells as low as ~2.3. A simple model consisting of a dipole magnetic field and constant, azimuthally westward, electric field is used to calculate the earthward and westward drift of 90° pitch angle ions. This model is applied to determine how far earthward ions can drift while remaining on Earth's night side, given the strength and duration of the convection electric field. The calculation based on this simp. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020875 Available at: http://doi.wiley.com/10.1002/2014JA020875
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Authors: Thaller S. A., Wygant J R, Dai L., Breneman A.W., Kersten K., et al.
Title: Van Allen Probes investigation of the large scale duskward electric field and its role in ring current formation and plasmasphere erosion in the June 1, 2013 storm
Abstract: Using the Van Allen Probes we investigate the enhancement in the large scale duskward convection electric field during the geomagnetic storm (Dst ~ −120 nT) on June 1, 2013 and its role in ring current ion transport and energization, and plasmasphere erosion. During this storm, enhancements of ~1-2 mV/m in the duskward electric field in the co-rotating frame are observed down to L shells as low as ~2.3. A simple model consisting of a dipole magnetic field and constant, azimuthally westward, electric field is used to calculate the earthward and westward drift of 90° pitch angle ions. This model is applied to determine how far earthward ions can drift while remaining on Earth's night side, given the strength and duration of the convection electric field. The calculation based on this simp. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020875 Available at: http://doi.wiley.com/10.1002/2014JA020875
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electric field response
Authors: Cattell C., Breneman A., Colpitts C., Dombeck J., Thaller S., et al.
Title: Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13
Abstract: Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated ExB flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by MMS, with a speed that is comparable to the ExB flow. The magnetopause speed and the ExB speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF. . .
Date: 08/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL074895 Available at: onlinelibrary.wiley.com/doi/10.1002/2017GL074895/full
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electric fields
Authors: Dai Lei, Wang Chi, Duan Suping, He Zhaohai, Wygant John R., et al.
Title: Near-Earth Injection of MeV Electrons associated with Intense Dipolarization Electric Fields: Van Allen Probes observations
Abstract: Substorms generally inject 10s-100s keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the pre-midnight sector at L∼5.5, Van Allen Probes (RBSP)-A observed a large dipolarization electric field (50mV/m) over ∼40s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the in. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064955 Available at: http://doi.wiley.com/10.1002/2015GL064955
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Authors: Dai Lei, Wang Chi, Duan Suping, He Zhaohai, Wygant John R., et al.
Title: Near-Earth Injection of MeV Electrons associated with Intense Dipolarization Electric Fields: Van Allen Probes observations
Abstract: Substorms generally inject 10s-100s keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the pre-midnight sector at L∼5.5, Van Allen Probes (RBSP)-A observed a large dipolarization electric field (50mV/m) over ∼40s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the in. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064955 Available at: http://doi.wiley.com/10.1002/2015GL064955
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electromagnetic ion-cyclotron
Authors: Clilverd Mark A., Duthie Roger, Hardman Rachael, Hendry Aaron T., Rodger Craig J., et al.
Title: Electron precipitation from EMIC waves: a case study from 31 May 2013
Abstract: On 31 May 2013 several rising-tone electromagnetic ion-cyclotron (EMIC) waves with intervals of pulsations of diminishing periods (IPDP) were observed in the magnetic local time afternoon and evening sectors during the onset of a moderate/large geomagnetic storm. The waves were sequentially observed in Finland, Antarctica, and western Canada. Co-incident electron precipitation by a network of ground-based Antarctic Arctic Radiation-belt Dynamic Deposition VLF Atmospheric Research Konsortia (AARDDVARK) and riometer instruments, as well as the Polar-orbiting Operational Environmental Satellite (POES) electron telescopes, was also observed. At the same time POES detected 30-80 keV proton precipitation drifting westwards at locations that were consistent with the ground-based observations, i. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021090 Available at: http://doi.wiley.com/10.1002/2015JA021090
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Authors: Clilverd Mark A., Duthie Roger, Hardman Rachael, Hendry Aaron T., Rodger Craig J., et al.
Title: Electron precipitation from EMIC waves: a case study from 31 May 2013
Abstract: On 31 May 2013 several rising-tone electromagnetic ion-cyclotron (EMIC) waves with intervals of pulsations of diminishing periods (IPDP) were observed in the magnetic local time afternoon and evening sectors during the onset of a moderate/large geomagnetic storm. The waves were sequentially observed in Finland, Antarctica, and western Canada. Co-incident electron precipitation by a network of ground-based Antarctic Arctic Radiation-belt Dynamic Deposition VLF Atmospheric Research Konsortia (AARDDVARK) and riometer instruments, as well as the Polar-orbiting Operational Environmental Satellite (POES) electron telescopes, was also observed. At the same time POES detected 30-80 keV proton precipitation drifting westwards at locations that were consistent with the ground-based observations, i. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021090 Available at: http://doi.wiley.com/10.1002/2015JA021090
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Electron acceleration
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
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Authors: Vasko I. Y., Agapitov O. V., Mozer F S, Artemyev A. V., Drake J. F., et al.
Title: Electron holes in the outer radiation belt: Characteristics and their role in electron energization
Abstract: Van Allen Probes have detected electron holes (EHs) around injection fronts in the outer radiation belt. Presumably generated near equator, EHs propagate to higher latitudes potentially resulting in energization of electrons trapped within EHs. This process has been recently shown to provide electrons with energies up to several tens of keV and requires EH propagation up to rather high latitudes. We have analyzed more than 100 EHs observed around a particular injection to determine their kinetic structure and potential energy sources supporting the energization of trapped electrons. EHs propagate with velocities from 1000 to 20,000 km/s (a few times larger than the thermal velocity of the coldest background electron population). The parallel scale of observed EHs is from 0.3 to 3 km that i. . .
Date: 12/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023083 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023083/full
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electron acoustic waves
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
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Electron density
Authors: Kurth W S, De Pascuale S., Faden J. B., Kletzing C A, Hospodarsky G B, et al.
Title: Electron Densities Inferred from Plasma Wave Spectra Obtained by the Waves Instrument on Van Allen Probes
Abstract: The twin Van Allen Probe spacecraft, launched in August 2012, carry identical scientific payloads. The Electric and Magnetic Fields Instrument Suite and Integrated Science (EMFISIS) suite includes a plasma wave instrument (Waves) that measures three magnetic and three electric components of plasma waves in the frequency range of 10 Hz to 12 kHz using triaxial search coils and the Electric Fields and Waves (EFW) triaxial electric field sensors. The Waves instrument also measures a single electric field component of waves in the frequency range of 10 to 500 kHz. A primary objective of the higher frequency measurements is the determination of the electron density ne at the spacecraft, primarily inferred from the upper hybrid resonance frequency fuh. Considerable work has gone into developing . . .
Date: 01/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020857 Available at: http://doi.wiley.com/10.1002/2014JA020857
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electron energy
Authors: Kellerman A. C., Shprits Y Y, Makarevich R. A., Spanswick E., Donovan E., et al.
Title: Characterization of the energy-dependent response of riometer absorption
Abstract: Ground based riometers provide an inexpensive means to continuously remote sense the precipitation of electrons in the dynamic auroral region of Earth's ionosphere. The energy-dependent relationship between riometer absorption and precipitating electrons is thus of great importance for understanding the loss of electrons from the Earth's magnetosphere. In this study, statistical and event-based analyses are applied to determine the energy of electrons to which riometers chiefly respond. Time-lagged correlation analysis of trapped to precipitating fluxes shows that daily averaged absorption best correlates with ~ 60 keV trapped electron flux at zero-time lag, although large variability is observed across different phases of the solar cycle. High-time resolution statistical cross-correlati. . .
Date: 11/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020027 Available at: http://doi.wiley.com/10.1002/2014JA020027
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electron hole
Authors: Contel O., Nakamura R, Breuillard H., Argall M. R., Graham D. B., et al.
Title: Lower-hybrid drift waves and electromagnetic electron space-phase holes associated with dipolarization fronts and field-aligned currents observed by the Magnetospheric Multiscale mission during a substorm
Abstract: We analyse two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on August 10, 2016. The first event corresponds to a fast dawnward flow with an anti-parallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower-hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing, and with a smaller lower-hybrid drift wave activity. Electromag. . .
Date: 10/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024550 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024550/full
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