Bibliography



Found 81 entries in the Bibliography.


Showing entries from 1 through 50


2020

The Relation Between Electron Cyclotron Harmonic Waves and Plasmapause: Case and Statistical Studies

Abstract Observationally, electron cyclotron harmonic (ECH) waves are often terminated at the outer boundary of the plasmasphere boundary layer (PBL, i.e., plasmapause). Physics of this empirical relation is not well established. In this study, two categories of ECH waves are shown by their different behaviors near PBL. For Category I, all bands of ECH waves terminate at PBL because the density ratio (nh/nc) between hot and cold electrons decreases dramatically across PBL. For Category II, ECH waves, especially the lower har ...

Liu, Xu; Chen, Lunjin; Xia, Zhiyang;

YEAR: 2020     DOI: 10.1029/2020GL087365

two types of ECH wave; Plasmapause; instability; excitation and attenuation mechanism; statistical characteristics of two types of ECH wave; Van Allen Probes

Localization of the Source of Quasiperiodic VLF Emissions in the Magnetosphere by Using Simultaneous Ground and Space Observations: A Case Study

Abstract We study quasiperiodic very low frequency (VLF) emissions observed simultaneously by Van Allen Probes spacecraft and Kannuslehto and Lovozero ground-based stations on 25 December 2015. Both Van Allen Probes A and B detected quasiperiodic emissions, probably originated from a common source, and observed on the ground. In order to locate possible regions of wave generation, we analyze wave-normal angles with respect to the geomagnetic field, Poynting flux direction, and cyclotron instability growth rate calculated by ...

Demekhov, A.; Titova, E.; Maninnen, J.; Pasmanik, D.; Lubchich, A.; Santolik, O.; Larchenko, A.; Nikitenko, A.; Turunen, T.;

YEAR: 2020     DOI: 10.1029/2020JA027776

quasiperiodic VLF emissions; Cyclotron instability; wave propagation; Magnetosphere; whistler mode waves; Van Allen Probes

Direct evidence of the pitch angle scattering of relativistic electrons induced by EMIC waves

In this study, we analyze an EMIC wave event of rising tone elements recorded by the Van Allen Probes. The pitch angle distributions of relativistic electrons exhibit a direct response to the two elements of EMIC waves: at the intermediate pitch angle the fluxes are lower and at the low pitch angle the fluxes are higher than those when no EMIC was observed. In particular, the observed changes in the pitch angle distributions are most likely to be caused by nonlinear wave particle interaction. The calculation of the minimum r ...

Zhu, Hui; Chen, Lunjin; Claudepierre, Seth; Zheng, Liheng;

YEAR: 2020     DOI: 10.1029/2019GL085637

EMIC waves; nonlinear wave-particle interaction; pitch angle scattering; Van Allen Probes

2019

On the Observation of Electrostatic Harmonics Associated With EMIC Waves

In this study, we report two events of electrostatic harmonics associated with electromagnetic ion cyclotron (EMIC) waves recorded by the Van Allen Probes. Based on the wave and plasma measurements, the wave features are investigated and the possible generation mechanism is discussed. The frequencies of these electrostatic emissions are at the integer and fractional frequencies of the fundamental EMIC waves, which can be across and above the local proton gyrofrequencies. When the frequencies increase, the electric power spec ...

Zhu, Hui; Chen, Lunjin;

YEAR: 2019     DOI: 10.1029/2019GL085528

EMIC waves; Harmonics; Van Allen Probes

Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves

Electromagnetic ion cyclotron (EMIC) waves are known to typically cause electron losses into Earth\textquoterights upper atmosphere at >~1 MeV, while the minimum energy of electrons subject to efficient EMIC-driven precipitation loss is unresolved. This letter reports electron precipitation from subrelativistic energies of ~250 keV up to ~1 MeV observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD-II) CubeSats, while two Polar Operational Environmental Satellites (POES) ...

Capannolo, L.; Li, W.; Ma, Q.; Chen, L.; Shen, X.-C.; Spence, H.; Sample, J.; Johnson, A.; Shumko, M.; Klumpar, D.; Redmon, R.;

YEAR: 2019     DOI: 10.1029/2019GL084202

electron precipitation; EMIC waves; FIREBIRD-II; quasi linear theory; Radiation belts; Van Allen Probes; wave particle interactions

Analyzing EMIC Waves in the Inner Magnetosphere Using Long-Term Van Allen Probes Observations

With 64-month magnetic data from Van Allen Probes, we have studied not only the global distribution, wave normal angle (θ), and ellipticity (ε) of electromagnetic ion cyclotron (EMIC) waves, but also the dependence of their occurrence rates and magnetic amplitudes on the AE* index (the mean value of AE index over previous 1 hr). Our results show that H+ band waves are preferentially detected at 5 <= L <= 6.5, in the noon sector. They typically have small θ (<30\textdegree) and weakly left-hand polarization but become more ...

Chen, Huayue; Gao, Xinliang; Lu, Quanming; Wang, Shui;

YEAR: 2019     DOI: 10.1029/2019JA026965

A long-term statistical work; EMIC wave; inner magnetosphere; spatial distribution; Van Allen Probes; Van Allen Probes observation; Wave fundamental characters

Statistical analysis on plasmatrough exohiss waves from the Van Allen Probes

In this study using Van Allen Probe wave observations we investigate the statistical properties of exohiss waves, which are structureless whistler mode waves observed outside the plasmapause. The exohiss waves are identified based on the cold electron number density, frequency distribution, ellipticity, and wave normal angle. The statistical analysis on exohiss wave properties shows that exohiss waves prefer to occur over 3

Zhu, Hui; Gu, Wenyao; Chen, Lunjin;

YEAR: 2019     DOI: 10.1029/2018JA026359

Exohiss; leaking process; Van Allen Probes

Diffuse Auroral Electron and Ion Precipitation Effects on RCM-E Comparisons with Satellite Data During the March 17, 2013 Storm

Effects of scattering of electrons from whistler chorus waves and of ions due to field line curvature on diffuse precipitating particle fluxes and ionospheric conductance during the large 17 March 2013 storm are examined using the self-consistent Rice Convection Model Equilibrium (RCM-E) model. Electrons are found to dominate the diffuse precipitating particle integrated energy flux, with large fluxes from ~21:00 magnetic local time (MLT) eastward to ~11:00 MLT during the storm main phase. Simulated proton and oxygen ion pre ...

Chen, Margaret; Lemon, Colby; Hecht, James; Sazykin, Stanislav; Wolf, Richard; Boyd, Alexander; Valek, Philip;

YEAR: 2019     DOI: 10.1029/2019JA026545

diffuse aurora; electron and ion precipitation; field-line curvature scattering; inner magnetospheric electric field; ionospheric conductance; simulations and data comparisons; Van Allen Probes

Triggered Plasmaspheric Hiss: Rising Tone Structures

In this study, a rare hiss event observed by Van Allen Probe is reported and the possible generation is investigated based on wave and plasma measurements. The results suggest that the normal hiss (from 0.05fce to 0.5fce) with dominantly equatorward Poynting fluxes is locally generated by plasma sheet electrons via cyclotron instability. The low-frequency band (from 30 Hz to 0.05fce) with a mixture of equatorward and poleward Poynting fluxes is probably due to multiple reflections inside the plasmasphere. Such difference in ...

Zhu, Hui; Liu, Xu; Chen, Lunjin;

YEAR: 2019     DOI: 10.1029/2019GL082688

Plasmaspheric Hiss; Radiation belts; Rising tone structure; Van Allen Probes

Global occurrences of electrostatic electron cyclotron harmonic waves associated with radiation belt electron distributions

Electrostatic electron cyclotron harmonic (ECH) waves can yield diffuse aurora primarily at higher L-shells by driving efficient precipitation loss of plasma sheet electrons. Here using the Van Allen Probes high resolution data, we examine in detail the global occurrences of ECH waves during the period from October 1, 2012 to June 30, 2017 and find that there are totally 419 events of enhanced ECH waves. The statistical results demonstrate that ECH waves can be present over a broad region of L=4-6 and 00-24 MLT, with a highe ...

Chen, Yaru; Zhou, Qinghua; He, Yihua; Yang, Chang; Liu, Si; Gao, Zhonglei; Xiao, Fuliang;

YEAR: 2019     DOI: 10.1029/2019GL082668

electron ring distribution; global occurrences; Radiation belt; Van Allen Probe observation; Van Allen Probes; waves

Modulation of Locally Generated Equatorial Noise by ULF Wave

In this paper we report a rare and fortunate event of fast magnetosonic (MS, also called equatorial noise) waves modulated by compressional ultralow frequency (ULF) waves measured by Van Allen Probes. The characteristics of MS waves, ULF waves, proton distribution, and their potential correlations are analyzed. The results show that ULF waves can modulate the energetic ring proton distribution and in turn modulate the MS generation. Furthermore, the variation of MS intensities is attributed to not only ULF wave activities bu ...

Zhu, Hui; Chen, Lunjin; Liu, Xu; Shprits, Yuri;

YEAR: 2019     DOI: 10.1029/2018JA026199

linear growth rate; magnetosonic waves; Radiation belts; ULF waves; Van Allen Probes

Observational evidence of the drift-mirror plasma instability in Earth\textquoterights inner magnetosphere

We report on evidence for the generation of an ultra-low frequency plasma wave by the drift-mirror plasma instability in the dynamic plasma environment of Earth\textquoterights inner magnetosphere. The plasma measurements are obtained from the Radiation Belt Storm Probes Ion Composition Experiment onboard NASA\textquoterights Van Allen Probes Satellites. We show that the measured wave-particle interactions are driven by the drift-mirror instability. Theoretical analysis of the data demonstrates that the drift-mirror mode pla ...

Soto-Chavez, A.; Lanzerotti, L.; Manweiler, J.; Gerrard, A.; Cohen, R.; Xia, Z.; Chen, L.; Kim, H.;

YEAR: 2019     DOI: 10.1063/1.5083629

Van Allen Probes

PreMevE: New Predictive Model for Megaelectron-volt Electrons inside Earth\textquoterights Outer Radiation Belt

This work designs a new model called PreMevE to predict storm-time distributions of relativistic electrons within Earth\textquoterights outer radiation belt. This model takes advantage of the cross-energy, -L-shell, and \textendashpitch-angle coherence associated with wave-electron resonant interactions, ingests observations from belt boundaries\textemdashmainly by NOAA POES in low-Earth-orbits (LEOs), and provides high-fidelity nowcast (multiple-hour prediction) and forecast (> ~1 day) of MeV electron fluxes over L-shells b ...

Chen, Yue; Reeves, Geoffrey; Fu, Xiangrong; Henderson, Michael;

YEAR: 2019     DOI: 10.1029/2018SW002095

event-specific predictions; LANL GEO observations; linear predictive filters; MeV electron events; outer radiation belt; precipitation at low-earth-orbits (LEO); Van Allen Probes

Van Allen Probes observations of chorus wave vector orientations: Implications for the chorus-to-hiss mechanism

Using observations from the Van Allen Probes EMFISIS instrument, coupled with ray tracing simulations, we determine the fraction of chorus wave power with the conditions required to access the plasmasphere and evolve into plasmaspheric hiss. It is found that only an extremely small fraction of chorus occurs with the required wave vector orientation, carrying only a small fraction of the total chorus wave power. The exception is on the edge of plasmaspheric plumes, where strong azimuthal density gradients are present. In thes ...

Hartley, D.; Kletzing, C.; Chen, L.; Horne, R.; ik, O.;

YEAR: 2019     DOI: 10.1029/2019GL082111

chorus waves; EMFISIS; Plasmaspheric Hiss; plasmaspheric plumes; Van Allen Probes; wave normal angle

Local Generation of High-Frequency Plasmaspheric Hiss Observed by Van Allen Probes

The generation of a high-frequency plasmaspheric hiss (HFPH) wave observed by Van Allen Probes is studied in this letter for the first time. The wave has a moderate power spectral density (\~10-6 nT2/Hz), with a frequency range extended from 2 to 10 kHz. The correlated observations of waves and particles indicate that HFPH is associated with the enhancement of electron flux during the substorm on 6 January 2014. Calculations of the wave linear growth rate driven by the fitted electron phase space density show that the electr ...

He, Zhaoguo; Chen, Lunjin; Liu, Xu; Zhu, Hui; Liu, Si; Gao, Zhonglei; Cao, Yong;

YEAR: 2019     DOI: 10.1029/2018GL081578

electron; high frequency; local generation; Plasmaspheric Hiss; substorm injection; Van Allen Probes

2018

An event on simultaneous amplification of exohiss and chorus waves associated with electron density enhancements

Whistler mode exohiss are the structureless hiss waves observed outside the plasmapause with featured equatorward Poynting flux. An event of the amplification of exohiss as well as chorus waves was recorded by Van Allen Probes during the recovery phase of a weak geomagnetic storm. Amplitudes of both types of the waves showed a significant increase at the regions of electron density enhancements. It is found that the electrons resonant with exohiss and chorus showed moderate pitch-angle anisotropies. The ratio of the number o ...

Zhu, Hui; Shprits, Yuri; Chen, Lunjin; Liu, Xu; Kellerman, Adam;

YEAR: 2018     DOI: 10.1029/2017JA025023

electromagnetic waves; Exohiss; linear theory; Radiation belts; Van Allen Probes

The Response of the Energy Content of the Outer Electron Radiation Belt to Geomagnetic Storms

Using the data from the Van Allen Probe-A spacecraft, the variability of the total outer radiation belt (2.5300 keV) is investigated for the first time during 51 isolated storms spanning from October 2012 to May 2017. The statistical results show that the TRBEEC exhibits no-change in 20\% of the storms and gets enhanced during 80\% of them. The sub-relativistic electrons (300-500 keV) and relativistic electrons (0.5-2.0 MeV) equally contribute to the TRBEEC du ...

Xiong, Ying; Xie, Lun; Chen, Lunjin; Ni, Binbin; Fu, Suiyan; Pu, Zuyin;

YEAR: 2018     DOI: 10.1029/2018JA025475

Chorus wave; energetic particles; energy content; magnetic storm; outer radiation belt; Van Allen Probes

Observed propagation route of VLF transmitter signals in the magnetosphere

Signals of powerful ground transmitters at various places have been detected by satellites in near-Earth space. The study on propagation mode, ducted or nonducted, has attracted much attentions for several decades. Based on the statistical results from Van Allen Probes (data from Oct. 2012 to Mar. 2017) and DEMETER satellite (from Jan. 2006 to Dec. 2007), we present the ground transmitter signals distributed clearly in ionosphere and magnetosphere. The observed propagation route in the meridian plane in the magnetosphere for ...

Zhang, Zhenxia; Chen, Lunjin; Li, Xinqiao; Xia, Zhiyang; Heelis, Roderick; Horne, Richard;

YEAR: 2018     DOI: 10.1029/2018JA025637

ducted propagation; in magnetosphere; nonducted propagation; Van Allen Probes; VLF transmitter

An empirical model of radiation belt electron pitch angle distributions based on Van Allen Probes measurements

Based on over 4 years of Van Allen Probes measurements, an empirical model of radiation belt electron equatorial pitch angle distribution (PAD) is constructed. The model, developed by fitting electron PADs with Legendre polynomials, provides the statistical PADs as a function of L-shell (L=1 \textendash 6), magnetic local time (MLT), electron energy (~30 keV \textendash 5.2 MeV), and geomagnetic activity (represented by the Dst index), and is also the first empirical PAD model in the inner belt and slot region. For MeV elect ...

Zhao, H.; Friedel, R.; Chen, Y.; Reeves, G.; Baker, D.; Li, X.; Jaynes, A.; Kanekal, S.; Claudepierre, S.; Fennell, J.; Blake, J.; Spence, H.;

YEAR: 2018     DOI: 10.1029/2018JA025277

Empirical Model; Geomagnetic storms; inner belt and slot region; Pitch angle distribution; radiation belt electrons; Van Allen Probes

The Radial Propagation Characteristics of the Injection Front: A Statistical Study Based on BD-IES and Van Allen Probes Observations

Electron flux measurements outside geosynchronous orbit (GSO) obtained by the BeiDa Imaging Electron Spectrometer instrument onboard a 55 degrees-inclined GSO satellite, and inside GSO obtained by the Van Allen Probes are analyzed to investigate the temporal and spatial evolutions of the substorm injection region. In one year data started from October 2015, 63 injection events are identified. Firstly, our study shows that the injection signatures can be detected in a large radial extent in one single event, for example, from ...

. Y. Liu, Z; Zong, Q.-G.; Hao, Y.; Liu, Y.; Chen, X.;

YEAR: 2018     DOI: 10.1002/2018JA025185

earthward propagation; radial propagation speed; substorm injection; tailward propagation; upper-cutoff magnetic moment; Van Allen Probes

Statistical Properties of Plasmaspheric Hiss from Van Allen Probes Observations

Van Allen Probes observations are used to statistically investigate plasmaspheric hiss wave properties. This analysis shows that the wave normal direction of plasmaspheric hiss is predominantly field aligned at larger L shells, with a bimodal distribution, consisting of a near-field aligned and a highly oblique component, becoming apparent at lower L shells. Investigation of this oblique population reveals that it is most prevalent at L < 3, frequencies with f/fce> 0.01 (or f> 700 Hz), low geomagnetic activity levels, and be ...

Hartley, D.; Kletzing, C.; ik, O.; Chen, L.; Horne, R.;

YEAR: 2018     DOI: 10.1002/2017JA024593

Bimodal; chorus waves; EMFISIS; Plasmaspheric Hiss; Van Allen Probes; wave normal angle

Fast Magnetosonic Waves Observed by Van Allen Probes: Testing Local Wave Excitation Mechanism

Linear Vlasov theory and particle-in-cell (PIC) simulations for electromagnetic fluctuations in a homogeneous, magnetized, and collisionless plasma are used to investigate a fast magnetosonic wave event observed by the Van Allen Probes. The fluctuating magnetic field observed exhibits a series of spectral peaks at harmonics of the proton cyclotron frequency Ωp and has a dominant compressional component, which can be classified as fast magnetosonic waves. Furthermore, the simultaneously observed proton phase space density ex ...

Min, Kyungguk; Liu, Kaijun; Wang, Xueyi; Chen, Lunjin; Denton, Richard;

YEAR: 2018     DOI: 10.1002/2017JA024867

Fast Magnetosonic Waves; inner magnetosphere; observation-simulation comparison; Van Allen Probes; wave excitation

One-Dimensional Full Wave Simulation of Equatorial Magnetosonic Wave Propagation in an Inhomogeneous Magnetosphere

The effect of the plasmapause on equatorially radially propagating fast magnetosonic (MS) waves in the Earth\textquoterights dipole magnetic field is studied by using finite difference time domain method. We run 1-D simulation for three different density profiles: (1) no plasmapause, (2) with a plasmapause, and (3) with a plasmapause accompanied with fine-scale density irregularity. We find that (1) without plasmapause the radially inward propagating MS wave can reach ionosphere and continuously propagate to lower altitude i ...

Liu, Xu; Chen, Lunjin; Yang, Lixia; Xia, Zhiyang; Malaspina, David;

YEAR: 2018     DOI: 10.1002/2017JA024336

fine-scale density structure; finite difference time domain; magnetosonic wave; Plasmapause; Van Allen Probes

2017

The Radiation Belt Electron Scattering by Magnetosonic Wave: Dependence on Key Parameters

Magnetosonic (MS) waves have been found capable of creating radiation belt electron butterfly distributions in the inner magnetosphere. To investigate the physical nature of the interactions between radiation belt electrons and MS waves, and to explore a preferential condition for MS waves to scatter electrons efficiently, we performed a comprehensive parametric study of MS wave-electron interactions using test particle simulations. The diffusion coefficients simulated by varying the MS wave frequency show that the scatterin ...

Lei, Mingda; Xie, Lun; Li, Jinxing; Pu, Zuyin; Fu, Suiyan; Ni, Binbin; Hua, Man; Chen, Lunjin; Li, Wen;

YEAR: 2017     DOI: 10.1002/2016JA023801

magnetosonic wave; parametric study; Radiation belt; Van Allen Probes; Wave-particle interaction

Analysis of the Duration of Rising Tone Chorus Elements

The duration of chorus elements is an important parameter to understand chorus excitation and to quantify the effects of nonlinear wave-particle interactions on energetic electron dynamics. In this work, we analyze the duration of rising tone chorus elements statistically using Van Allen Probes data. We present the distribution of chorus element duration (τ) as a function of magnetic local time (MLT) and the geomagnetic activity level characterized by auroral electrojet (AE) index. We show that the typical value of τ for n ...

Teng, S.; Tao, X.; Xie, Y.; Zonca, F.; Chen, L.; Fang, W.; Wang, S.;

YEAR: 2017     DOI: 10.1002/2017GL075824

chorus element duration; DAWN; frequency chirping rate; Van Allen Probes

Multiple-satellite observation of magnetic dip event during the substorm on 10 October, 2013

We present a multiple-satellite observation of the magnetic dip event during the substorm on October 10, 2013. The observation illustrates the temporal and spatial evolution of the magnetic dip and gives a compelling evidence that ring current ions induce the magnetic dip by enhanced plasma beta. The dip moves with the energetic ions in a comparable drift velocity and affects the dynamics of relativistic electrons in the radiation belt. In addition, the magnetic dip provides a favorable condition for the EMIC wave generation ...

He, Zhaoguo; Chen, Lunjin; Zhu, Hui; Xia, Zhiyang; Reeves, G.; Xiong, Ying; Xie, Lun; Cao, Yong;

YEAR: 2017     DOI: 10.1002/2017GL074869

EMIC wave; magnetic dip; radiation belt electrons; Ring current ions; Van Allen Probes

The characteristic response of whistler mode waves to interplanetary shocks

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 p ...

Yue, Chao; Chen, Lunjin; Bortnik, Jacob; Ma, Qianli; Thorne, Richard; Angelopoulos, Vassilis; Li, Jinxing; An, Xin; Zhou, Chen; Kletzing, Craig; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2017     DOI: 10.1002/2017JA024574

IP shocks; MLT dependent; Plasmaspheric Hiss; Ray Tracing; Van Allen Probes; whistler mode chorus

Relativistic electron dynamics produced by azimuthally localized poloidal mode ULF waves: Boomerang-shaped pitch angle evolutions

We present an analysis of \textquotedblleftboomerang-shaped\textquotedblright pitch angle evolutions of outer radiation belt relativistic electrons observed by the Van Allen Probes after the passage of an interplanetary shock on June 7th, 2014. The flux at different pitch angles is modulated by Pc5 waves, with equatorially mirroring electrons reaching the satellite first. For 90o pitch angle electrons, the phase change of the flux modulations across energy exceeds 180o, and increasingly tilts with time. Using estimates of th ...

Hao, Y.; Zong, Q.-G.; Zhou, X.-Z.; Rankin, R.; Chen, X.; Liu, Y.; . Y. Fu, S; Spence, H.; Blake, J.; Reeves, G.;

YEAR: 2017     DOI: 10.1002/2017GL074006

drift resonance; interplanetary shock; localized waves; Radiation belts; ULF waves; Van Allen Probes; Wave-particle interaction

Van Allen Probes observations of whistler-mode chorus with long-lived oscillating tones

Whistler-mode chorus plays an important role in the radiation belt electron dynamics. In the frequency-time spectrogram, chorus often appears as a hiss-like band and/or a series of short-lived (up to \~1 s) discrete elements. Here we present some rarely reported chorus emissions with long-lived (up to 25 s) oscillating tones observed by the Van Allen Probes in the dayside (MLT \~9\textendash14) midlatitude (|MLAT|>15\textdegree) region. An oscillating tone can behave either regularly or irregularly and can even transform int ...

Gao, Zhonglei; Su, Zhenpeng; Chen, Lunjin; Zheng, Huinan; Wang, Yuming; Wang, Shui;

YEAR: 2017     DOI: 10.1002/2017GL073420

Chorus; falling tone; nonlinear generation; oscillating tone; rising tone; Van Allen Probes

Relativistic electron\textquoterights butterfly pitch angle distribution modulated by localized background magnetic field perturbation driven by hot ring current ions

Dayside modulated relativistic electron\textquoterights butterfly pitch angle distributions (PADs) from \~200 keV to 2.6 MeV were observed by Van Allen Probe B at L = 5.3 on 15 November 2013. They were associated with localized magnetic dip driven by hot ring current ion (60\textendash100 keV proton and 60\textendash200 keV helium and oxygen) injections. We reproduce the electron\textquoterights butterfly PADs at satellite\textquoterights location using test particle simulation. The simulation results illustrate that a negat ...

Xiong, Ying; Chen, Lunjin; Xie, Lun; Fu, Suiyan; Xia, Zhiyang; Pu, Zuyin;

YEAR: 2017     DOI: 10.1002/2017GL072558

butterfly distribution; Radiation belt; ring current; Van Allen Probes

Propagation characteristics of plasmaspheric hiss: Van Allen Probe observations and global empirical models

Based on the Van Allen Probe A observations from 1 October 2012 to 31 December 2014, we develop two empirical models to respectively describe the hiss wave normal angle (WNA) and amplitude variations in the Earth\textquoterights plasmasphere for different substorm activities. The long-term observations indicate that the plasmaspheric hiss amplitudes on the dayside increase when substorm activity is enhanced (AE index increases), and the dayside hiss amplitudes are greater than the nightside. However, the propagation angles ( ...

Yu, J.; . Y. Li, L; Cao, J.; Chen, L.; Wang, J.; Yang, J.;

YEAR: 2017     DOI: 10.1002/2016JA023372

hiss amplitude model; hiss wave amplitude; Plasmaspheric Hiss; propagation angle model of hiss waves; substorm dependence; Van Allen Probes; wave normal angle

Variations of the relativistic electron flux after a magnetospheric compression event

On January 21, 2015, a sharp increase of the solar wind dynamic pressure impacted the magnetosphere. The magnetopause moved inward to the region L< 8 without causing a geomagnetic storm. The flux of the relativistic electrons in the outer radiation belt decreased by half during this event based on the observations of the particle radiation monitor (PRM) of the fourth of the China-Brazil Earth Resource Satellites (CBERS-4). The flux remained low for approximately 11 d; it did not recover after a small magnetic storm on Januar ...

Chen, Zhe; Chen, HongFei; Li, YiFan; Xiang, HongWen; Yu, XiangQian; Shi, WeiHong; Hao, ZhiHua; Zou, Hong; Zou, JiQing; Zhong, WeiYing;

YEAR: 2017     DOI: 10.1007/s11431-016-9008-3

outer radiation belt high-energy electrons medium-energy electrons space environment; Van Allen Probes

Variations of the relativistic electron flux after a magnetospheric compression event

On January 21, 2015, a sharp increase of the solar wind dynamic pressure impacted the magnetosphere. The magnetopause moved inward to the region L< 8 without causing a geomagnetic storm. The flux of the relativistic electrons in the outer radiation belt decreased by half during this event based on the observations of the particle radiation monitor (PRM) of the fourth of the China-Brazil Earth Resource Satellites (CBERS-4). The flux remained low for approximately 11 d; it did not recover after a small magnetic storm on Januar ...

Chen, Zhe; Chen, HongFei; Li, YiFan; Xiang, HongWen; Yu, XiangQian; Shi, WeiHong; Hao, ZhiHua; Zou, Hong; Zou, JiQing; Zhong, WeiYing;

YEAR: 2017     DOI: 10.1007/s11431-016-9008-3

outer radiation belt high-energy electrons medium-energy electrons space environment; Van Allen Probes

Van Allen Probes observation of a 360\textdegree phase shift in the flux modulation of injected electrons by ULF waves

We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of \~450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (\~50 to 150 keV) across the estimated resonant energy (\~104 keV) is \~360\textdegree. This phase relationship is different from the characteristic 180\textdegree phase shift as expected from ...

Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, Bernard; Wygant, J.; Kletzing, C.;

YEAR: 2017     DOI: 10.1002/2016GL071252

drift resonance; injection; PSD gradient; ULF waves; Van Allen Probes

Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to ~4.3 RE over 3 h during a relatively quiet period. The modulation of 150\textendash500 Hz plasmaspheric hiss was correlated with whist ...

Li, Jinxing; Bortnik, Jacob; Li, Wen; Thorne, Richard; Ma, Qianli; Chu, Xiangning; Chen, Lunjin; Kletzing, Craig; Kurth, William; Hospodarsky, George; Wygant, John; Breneman, Aaron; Thaller, Scott;

YEAR: 2017     DOI: 10.1002/2016JA023706

coherent waves; multisatellite; periodic rising tone; Van Allen Probes; whistler mode

Coherently modulated whistler mode waves simultaneously observed over unexpectedly large spatial scales

Utilizing simultaneous twin Van Allen Probes observations of whistler mode waves at variable separations, we are able to distinguish the temporal variations from spatial variations, determine the coherence spatial scale, and suggest the possible mechanism of wave modulation. The two probes observed coherently modulated whistler mode waves simultaneously at an unexpectedly large distance up to ~4.3 RE over 3 h during a relatively quiet period. The modulation of 150\textendash500 Hz plasmaspheric hiss was correlated with whist ...

Li, Jinxing; Bortnik, Jacob; Li, Wen; Thorne, Richard; Ma, Qianli; Chu, Xiangning; Chen, Lunjin; Kletzing, Craig; Kurth, William; Hospodarsky, George; Wygant, John; Breneman, Aaron; Thaller, Scott;

YEAR: 2017     DOI: 10.1002/2016JA023706

coherent waves; multisatellite; periodic rising tone; Van Allen Probes; whistler mode

Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B

We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions\textquoteright polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities ...

Khazanov, G.; Boardsen, S.; Krivorutsky, E.; Engebretson, M.; Sibeck, D.; Chen, S.; Breneman, A.;

YEAR: 2017     DOI: 10.1002/2016JA022814

nonlinear phenomena; parametric processes; Van Allen Probes; wave/wave interactions

Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B

We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions\textquoteright polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities ...

Khazanov, G.; Boardsen, S.; Krivorutsky, E.; Engebretson, M.; Sibeck, D.; Chen, S.; Breneman, A.;

YEAR: 2017     DOI: 10.1002/2016JA022814

nonlinear phenomena; parametric processes; Van Allen Probes; wave/wave interactions

Transitional behavior of different energy protons based on Van Allen Probes observations

Understanding the dynamical behavior of ~1 eV to 50 keV ions and identifying the energies at which the morphologies transit are important in that they involve the relative intensities and distributions of the large-scale electric and magnetic fields, the outflow, and recombination rates. However, there have been only few direct observational investigations of the transition in drift behaviors of different energy ions before the Van Allen Probes era. Here we statistically analyze ~1 eV to 50 keV hydrogen (H+) differential flu ...

Yue, Chao; Bortnik, Jacob; Chen, Lunjin; Ma, Qianli; Thorne, Richard; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2017     DOI: 10.1002/2016GL071324

Transition in drift behavior; UBK method; Van Allen Probes

2016

Transitional behavior of different energy protons based on Van Allen Probes observations

Understanding the dynamical behavior of ~1 eV to 50 keV ions and identifying the energies at which the morphologies transit are important in that they involve the relative intensities and distributions of the large-scale electric and magnetic fields, the outflow and recombination rates. However, there have been only few direct observational investigations of the transition in drift behaviors of different energy ions before the Van Allen Probes era. Here, we statistically analyze ~1 eV to 50 keV Hydrogen (H+) differential flu ...

Yue, Chao; Bortnik, Jacob; Chen, Lunjin; Ma, Qianli; Thorne, Richard; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2016     DOI: 10.1002/2016GL071324

Transition in drift behavior; UBK method; Van Allen Probes

Van Allen Probes observation of a 360\textdegree phase shift in the flux modulation of injected electrons by ULF waves

We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultra-low frequency (ULF) waves on October 29, 2013. Oscillations in electron flux were observed at the period of \~450s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (\~50 to 150 keV) across the estimated resonant energy (\~104 keV) is \~360\textdegree. This phase relationship is different from the characteristic 180\textdegree phase shift as expected from ...

Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, Bernard; Wygant, John; Kletzing, Craig;

YEAR: 2016     DOI: 10.1002/2016GL071252

drift-resonance; injection; PSD gradient; ULF waves; Van Allen Probes

Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

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 ...

Xia, Zhiyang; Chen, Lunjin; Dai, Lei; Claudepierre, Seth; Chan, Anthony; Soto-Chavez, A.; Reeves, G.;

YEAR: 2016     DOI: 10.1002/2016GL070280

chorus modulation; inner magnetosphere; ULF wave; Van Allen Probes; whistler wave

Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event

Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth\textquoterights outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the presen ...

Zhang, X.-J.; Li, W.; Thorne, R.; Angelopoulos, V.; Ma, Q.; Li, J.; Bortnik, J.; Nishimura, Y.; Chen, L.; Baker, D.; Reeves, G.; Spence, H.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Blake, J.; Fennell, J.;

YEAR: 2016     DOI: 10.1002/2016JA022517

Drift shell splitting; dropouts; magnetic storm; magnetopause shadowing; outer radiation belt; relativistic electron loss; Van Allen Probes

RAM-SCB simulations of electron transport and plasma wave scattering during the October 2012 \textquotedblleftdouble-dip\textquotedblright storm

Mechanisms for electron injection, trapping, and loss in the near-Earth space environment are investigated during the October 2012 \textquotedblleftdouble-dip\textquotedblright storm using our ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB). Pitch angle and energy scattering are included for the first time in RAM-SCB using L and magnetic local time (MLT)-dependent event-specific chorus wave models inferred from NOAA Polar-orbiting Operational Environmental Satellites (POES) and Van Al ...

Jordanova, V.; Tu, W.; Chen, Y.; Morley, S.; Panaitescu, A.-D.; Reeves, G.; Kletzing, C.;

YEAR: 2016     DOI: 10.1002/2016JA022470

Geomagnetic storms; inner magnetosphere; Van Allen Probes

Direct evidence for EMIC wave scattering of relativistic electrons in space

Electromagnetic ion cyclotron (EMIC) waves have been proposed to cause efficient losses of highly relativistic (>1 MeV) electrons via gyroresonant interactions. Simultaneous observations of EMIC waves and equatorial electron pitch angle distributions, which can be used to directly quantify the EMIC wave scattering effect, are still very limited, however. In the present study, we evaluate the effect of EMIC waves on pitch angle scattering of ultrarelativistic (>1 MeV) electrons during the main phase of a geomagnetic storm, wh ...

Zhang, X.-J.; Li, W.; Ma, Q.; Thorne, R.; Angelopoulos, V.; Bortnik, J.; Chen, L.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Baker, D.; Reeves, G.; Spence, H.; Blake, J.; Fennell, J.;

YEAR: 2016     DOI: 10.1002/2016JA022521

electron precipitation; EMIC waves; equatorial pitch angle distribution; Fokker-Planck equation; relativistic electron loss; Van Allen Probes; Wave-particle interaction

Electron butterfly distribution modulation by magnetosonic waves

The butterfly pitch angle distribution is observed as a dip in an otherwise normal distribution of electrons centered about αeq=90\textdegree. During storm times, the formation of the butterfly distribution on the nightside magnetosphere has been attributed to L shell splitting combined with magnetopause shadowing and strong positive radial flux gradients. It has been shown that this distribution can be caused by combined chorus and magnetosonic wave scattering where the two waves work together but at different local times. ...

Maldonado, Armando; Chen, Lunjin; Claudepierre, Seth; Bortnik, Jacob; Thorne, Richard; Spence, Harlan;

YEAR: 2016     DOI: 10.1002/2016GL068161

butterfly; electron; magnetosonic; Magnetosphere; Van Allen Probes; wave particle interaction

Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance

Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90\textdegree, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been ...

Li, Jinxing; Ni, Binbin; Ma, Qianli; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Thorne, R.; Bortnik, J.; Chen, Lunjin; Li, Wen; Baker, Daniel; Kletzing, Craig; Kurth, William; Hospodarsky, George; Fennell, Joseph; Reeves, Geoffrey; Spence, Harlan; Funsten, Herbert; Summers, Danny;

YEAR: 2016     DOI: 10.1002/2016GL067853

butterfly distributions; energetic electrons; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

Charged particle behavior in the growth and damping stages of ultralow frequency waves: theory and Van Allen Probes observations

Ultralow frequency (ULF) electromagnetic waves in Earth\textquoterights magnetosphere can accelerate charged particles via a process called drift resonance. In the conventional drift-resonance theory, a default assumption is that the wave growth rate is time-independent, positive, and extremely small. However, this is not the case for ULF waves in the real magnetosphere. The ULF waves must have experienced an earlier growth stage when their energy was taken from external and/or internal sources, and as time proceeds the wave ...

Zhou, Xu-Zhi; Wang, Zi-Han; Zong, Qiu-Gang; Rankin, Robert; Kivelson, Margaret; Chen, Xing-Ran; Blake, Bernard; Wygant, John; Kletzing, Craig;

YEAR: 2016     DOI: 10.1002/2016JA022447

drift resonance; Radiation belt; ULF waves; Van Allen Probes; wave growth and damping; Wave-particle interaction

Forecasting and remote sensing outer belt relativistic electrons from low Earth orbit

This study demonstrates the feasibility and reliability of using observations from low Earth orbit (LEO) to forecast and nowcast relativistic electrons in the outer radiation belt. We first report a high cross-energy, cross-pitch-angle coherence discovered between the trapped MeV electrons and precipitating approximately hundreds (~100s) of keV electrons\textemdashobserved by satellites with very different altitudes\textemdashwith correlation coefficients as high as ≳ 0.85. Based upon the coherence, we then tested the feas ...

Chen, Yue; Reeves, Geoffrey; Cunningham, Gregory; Redmon, Robert; Henderson, Michael;

YEAR: 2016     DOI: 10.1002/2015GL067481

forecast and nowcast; hundreds of keV precipitating electrons; LEO observations; Radiation belts; relativistic electrons; wave particle interactions

Determination of the Earth\textquoterights plasmapause location from the CE-3 EUVC images

The Moon-based Extreme Ultraviolet Camera (EUVC) aboard China\textquoterights Chang\textquoterighte-3 (CE-3) mission has successfully imaged the entire Earth\textquoterights plasmasphere for the first time from the side views on lunar surface. An EUVC image on 21 April 2014 is used in this study to demonstrate the characteristics and configurations of the Moon-based EUV imaging and to illustrate the determination algorithm of the plasmapause locations on the magnetic equator. The plasmapause locations determined from all the ...

He, Fei; Zhang, Xiao-Xin; Chen, Bo; Fok, Mei-Ching;

YEAR: 2016     DOI: 10.1002/2015JA021863

Chang\textquoterighte-3; EUV imaging; Plasmapause; plasmasphere; reconstruction



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