Bibliography



Found 113 entries in the Bibliography.


Showing entries from 1 through 50


2021

Trapping and amplification of unguided mode EMIC waves in the radiation belt

AbstractElectromagnetic ion cyclotron (EMIC) waves can cause the scattering loss of the relativistic electrons in the radiation belt. They can be classified into the guided mode and the unguided mode, according to waves propagation behavior. The guided mode waves have been widely investigated in the radiation belt, but the observation of the unguided mode waves have not been expected. Based on the observations of Van Allen Probes, we demonstrate for the first time the existence of the intense unguided L-mode EMIC waves in th ...

Wang, Geng; Gao, Zhonglei; Wu, MingYu; Wang, GuoQiang; Xiao, SuDong; Chen, YuanQiang; Zou, Zhengyang; Zhang, TieLong;

YEAR: 2021     DOI: https://doi.org/10.1029/2021JA029322

EMIC waves; unguided mode; Radiation belt; ion abundance ratios; Wave trapping; growth rate; Van Allen Probes

PreMevE Update: Forecasting Ultra-relativistic Electrons inside Earth’s Outer Radiation Belt

Abstract Energetic electrons inside Earth’s Van Allen belts pose a major radiation threat to space-borne electronics that often play vital roles in modern society. Ultra-relativistic electrons with energies greater than or equal to two Megaelectron-volt (MeV) are of particular interest, and thus forecasting these ≥2 MeV electrons has significant meaning to all space sectors. Here we update the latest development of the predictive model for MeV electrons in the outer radiation belt. The new version, called PreMevE-2E, for ...

Sinha, Saurabh; Chen, Yue; Lin, Youzuo; de Lima, Rafael;

YEAR: 2021     DOI: https://doi.org/10.1029/2021SW002773

Supervised Machine Learning; Van Allen electron radiation belt; Predicting ultra-relativistic electrons; Van Allen Probes

Observational evidence of the excitation of magnetosonic waves by an He ion ring distribution

Abstract We report plasma wave observations of equatorial magnetosonic waves at integer harmonics of the local gyrofrequency of doubly-ionized helium (He). The waves were observed by Van Allen Probe A on 08 Feb 2014 when the spacecraft was in the afternoon magnetic local time sector near inside of the plasmasphere. Analysis of the complementary in-situ energetic ion measurements (1-300 keV) reveals the presence of a helium ion ring distribution centered near 30 keV. Theoretical linear growth rate calculations suggest that th ...

Claudepierre, S.; Liu, X.; Chen, L.; Takahashi, K.;

YEAR: 2021     DOI: https://doi.org/10.1029/2021JA029532

magnetosonic waves; ion Bernstein waves; ring distribution; alpha particles; Plasma instability; ring current; Van Allen Probes

ULF-modulation of whistler-mode waves in the inner magnetosphere during solar wind compression

Abstract The solar wind plays important roles on terrestrial magnetosphere dynamics, including the particle population and plasma waves generation. Here we report an interesting event that ULF waves are enhanced right after solar wind compression and the compressional mode ULF wave subsequently modulates both the intensity and energy flux direction of whistler-mode waves. Quasi-periodic whistler-mode wave packets are observed around L=5.6 at noon sector by Van Allen Probes. Growth rate calculation demonstrates that the compr ...

Shang, Xiongjun; Liu, Si; Chen, Lunjin; Gao, Zhonglei; Wang, Geng; He, Qian; Li, Tong; Xiao, Fuliang;

YEAR: 2021     DOI: https://doi.org/10.1029/2021JA029353

Van Allen Probes

Direct evidence reveals transmitter signal propagation in the magnetosphere

AbstractSignals from very-low-frequency transmitters on the ground are known to induce energetic electron precipitation from the Earth’s radiation belts. The effectiveness of this mechanism depends on the propagation characteristics of those signals in the magnetosphere, and in particular whether the signals are ducted or nonducted along channels of enhanced plasma density, analogous to optical fibres. Here we perform a statistical analysis of in-situ waveform data collected by the Van Allen Probes satellites that shows th ...

Gu, Wenyao; Chen, Lunjin; Xia, Zhiyang; Horne, Richard;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL093987

VLF transmitters; ducted propagation; nonducted propagation; Magnetosphere; Van Allen Probes

Frequency-Dependent Modulation of Whistler-mode Waves By Density Irregularities During the Recovery Phase of a Geomagnetic Storm

Abstract Density irregularities near the plasmapause are commonly observed and play an important role in whistler-mode wave excitation and propagation. In this study, we report a frequency-dependent modulation event of whistler-mode waves by background density irregularities during a geomagnetic storm. Higher-frequency whistler waves (near 0.5 fce, where fce is the equatorial electron cyclotron frequency) are trapped in the density trough regions due to the small refractive index near the parallel direction, while lower-freq ...

Liu, Xu; Gu, Wenyao; Xia, Zhiyang; Chen, Lunjin; Horne, Richard;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL093095

Van Allen Probes

The Characteristics of Three-belt Structure of Sub-MeV Electrons in the Radiation Belts

Abstract After the launch of Van Allen Probes, the three-belt structures of ultra-relativistic electrons are discovered. In this study, we investigate the three-belt structures of sub-MeV electrons, which may form under different mechanism compared with those of ultra-relativistic electrons and are worth in-depth analysis. Based on the differential flux data from MagEIS onboard RBSP-B satellite, we find 54 events, in which two comparable peaks of sub-MeV electron fluxes and a slot appear where there should be the outer radia ...

Li, Yu-Xuan; Yue, Chao; Hao, Yi-Xin; Zong, Qiu-Gang; Zhou, Xu-Zhi; Fu, Sui-Yan; Chen, Xing-Ran; Zhao, Xing-Xin;

YEAR: 2021     DOI: https://doi.org/10.1029/2021JA029385

Van Allen Probes

Origin of Electron Boomerang Stripes: Statistical Study

Abstract In the outer radiation belt, localized ULF waves can interact with energetic electrons by drift resonance, leading to quasiperiodic oscillations. The oscillations in the pitch angle spectrum can be characterized by either boomerang-shaped or straight stripes. Previous studies have shown that boomerang-shaped stripes evolve from straight ones when electrons drift away from the localized wave interaction region. Based on the time-of-flight technique on the pitch angle-dependent drift velocity, the origin can be remote ...

Zhao, X.; Hao, Y.; Zong, Q.; Zhou, X.; Yue, Chao; Chen, X.; Liu, Y.; Liu, Z.-Y.; Blake, J.; Claudepierre, S.; Reeves, G.;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL093377

Localized ULF waves; Energetic Elctrons; drift resonance; Time-of-flight Technique; source region; boomerang-shaped stripes; Van Allen Probes

A Statistical Study of Lower Hybrid Waves In the Earth’s Magnetosphere by Van Allen Probes

Abstract The lower hybrid (LH) waves are electrostatic emissions near the LH resonant frequency. They propagate perpendicularly with a small wavelength comparable to Larmor radius of thermal particles and can heat both ions and electrons. In this paper, we statistically study the global distribution of LH waves in the inner magnetosphere by using Van Allen Probes observation from 2012 to 2018. We find that (1) LH waves are commonly observed in the inner magnetosphere. Most LH waves are confined near the magnetic equator with ...

Liu, Xu; Chen, Lunjin; Ma, Qianli;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL093168

Van Allen Probes

Observational Evidence for Whistler Waves Guided/Ducted by the Inner and Outer Edges of the Plasmapause

Abstract With Van Allen Probes data, we present the observational support for whistler waves guided by the plasmapause based on a case study and statistical analyses. Due to the combined effects of inhomogeneous magnetic fields and plasma densities, whistler waves near the inner edge of plasmapause (plasmasphere side) will be guided by a HDD-like (HDD, high density duct) density gradient, and tend to have very small wave normal angles (WNAs ≤20°). In contrast, whistler waves around the outer edge of the plasmapause (plasm ...

Chen, Rui; Gao, Xinliang; Lu, Quanming; Tsurutani, Bruce; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL092652

Plasmapause; whistler wave; ducting effect; inner edge; outer edge; wave normal angle; Van Allen Probes

Whistler-mode waves trapped by density irregularities in the Earth s magnetosphere

Abstract Whistler-mode waves are electromagnetic waves pervasively observed in the Earth s and other planetary magnetospheres. They are considered to be mainly responsible for producing the hazardous radiation and diffuse aurora, which heavily relies on their properties. Density irregularities, frequently observed in the Earth s magnetospheres, are found to change largely the properties of whistler-mode waves. Here we report, using Van Allen Probes measurements, whistler-mode waves strongly modulated by two different density ...

Ke, Yangguang; Chen, Lunjin; Gao, Xinliang; Lu, Quanming; Wang, Xueyi; Chen, Rui; Chen, Huayue; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2020GL092305

WHISTLER-MODE WAVES; density irregularities; Magnetosphere; Radiation belts; particle-in-cell simulation; Wave trapping; Van Allen Probes

Whistler-mode waves trapped by density irregularities in the Earth s magnetosphere

Abstract Whistler-mode waves are electromagnetic waves pervasively observed in the Earth s and other planetary magnetospheres. They are considered to be mainly responsible for producing the hazardous radiation and diffuse aurora, which heavily relies on their properties. Density irregularities, frequently observed in the Earth s magnetospheres, are found to change largely the properties of whistler-mode waves. Here we report, using Van Allen Probes measurements, whistler-mode waves strongly modulated by two different density ...

Ke, Yangguang; Chen, Lunjin; Gao, Xinliang; Lu, Quanming; Wang, Xueyi; Chen, Rui; Chen, Huayue; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2020GL092305

WHISTLER-MODE WAVES; density irregularities; Magnetosphere; Radiation belts; particle-in-cell simulation; Wave trapping; Van Allen Probes

Whistler-mode waves trapped by density irregularities in the Earth s magnetosphere

Abstract Whistler-mode waves are electromagnetic waves pervasively observed in the Earth s and other planetary magnetospheres. They are considered to be mainly responsible for producing the hazardous radiation and diffuse aurora, which heavily relies on their properties. Density irregularities, frequently observed in the Earth s magnetospheres, are found to change largely the properties of whistler-mode waves. Here we report, using Van Allen Probes measurements, whistler-mode waves strongly modulated by two different density ...

Ke, Yangguang; Chen, Lunjin; Gao, Xinliang; Lu, Quanming; Wang, Xueyi; Chen, Rui; Chen, Huayue; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2020GL092305

WHISTLER-MODE WAVES; density irregularities; Magnetosphere; Radiation belts; particle-in-cell simulation; Wave trapping; Van Allen Probes

A comparative study on the distributions of incoherent and coherent plasmaspheric hiss

Abstract We perform a comparative study on the distributions of incoherent and coherent plasmaspheric hiss, based on the Van Allen Probe data. The statistics show that incoherent hiss ( ∼10–20 pT) is widely distributed in dayside plasmasphere, with peak frequencies below 500 Hz; intense coherent hiss (amplitudes up to 80 pT) occurs in outer plasmasphere of L > 4 (L denotes the L-shell.), whose frequency increases with ambient magnetic field significantly. The Poynting flux analysis indicates that incoherent hiss generall ...

He, Zhaoguo; Yu, Jiang; Li, Kun; Liu, Nigang; Chen, Zewen; Cui, Jun;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL092902

Van Allen Probes

In situ Observations of Whistler-mode Chorus Waves Guided by Density Ducts

Abstract In this paper, we report the proof of the existence of density ducts in the Earth’s magnetosphere by studying in situ observations of whistler-mode chorus waves using NASA’s Van Allen Probe-A data. Chorus waves, originally excited inside the density ducts with wave normal angles (WNAs) smaller than the Gendrin angle at near equator region, are efficiently confined to a limited area inside density ducts (i.e., ducted regions), and remain with small WNAs as they propagate towards high latitudes. The ducted region ...

Chen, Rui; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tsurutani, Bruce; Li, Wen; Ni, Binbin; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028814

Radiation belt; Chorus wave; density duct; ducted region; Van Allen Probes

In situ Observations of Whistler-mode Chorus Waves Guided by Density Ducts

Abstract In this paper, we report the proof of the existence of density ducts in the Earth’s magnetosphere by studying in situ observations of whistler-mode chorus waves using NASA’s Van Allen Probe-A data. Chorus waves, originally excited inside the density ducts with wave normal angles (WNAs) smaller than the Gendrin angle at near equator region, are efficiently confined to a limited area inside density ducts (i.e., ducted regions), and remain with small WNAs as they propagate towards high latitudes. The ducted region ...

Chen, Rui; Gao, Xinliang; Lu, Quanming; Chen, Lunjin; Tsurutani, Bruce; Li, Wen; Ni, Binbin; Wang, Shui;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028814

Radiation belt; Chorus wave; density duct; ducted region; Van Allen Probes

2020

Equatorial pitch angle distributions of 1 – 50 keV electrons in Earth s inner magnetosphere: an empirical model based on the Van Allen Probes observations

Using seven years of data from the HOPE instrument on the Van Allen Probes, equatorial pitch angle distributions (PADs) of 1 – 50 keV electrons in Earth s inner magnetosphere are investigated statistically. An empirical model of electron equatorial PADs as a function of radial distance, magnetic local time, geomagnetic activity, and electron energy is constructed using the method of Legendre polynomial fitting. Model results show that most equatorial PADs of 1 – 10s of keV electrons in Earth s inner magnetosphere are pan ...

Zhao, H.; Friedel, R.; Chen, Y.; Baker, D.; Li, X.; Malaspina, D.; Larsen, B.; Skoug, R.; Funsten, H.; Reeves, G.; Boyd, A.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028322

Pitch angle distribution; energetic electrons; Earth s inner magnetosphere; Anisotropy; Chorus wave; statistical analysis; Van Allen Probes

Ring Current Decay During Geomagnetic Storm Recovery Phase: Comparison Between RBSP Observations and Theoretical Modeling

Ring current decay during storm recovery phase may be affected by different loss processes. In this study, we have investigated the lifetimes of ring current ions (H+ and O+) of energies from 1 keV to several hundred keV at L shell from 3 to 6 during the storm recovery phase through a statistical survey. The observational data of 48 geomagnetic storms from March 2013 to May 2019 are collected based on Van Allen Probe observations. We find that (1) the observed lifetimes of H+ and O+ in general increase with L shell and (2) ...

Chen, Ao; Yue, Chao; Chen, HongFei; Zong, Qiugang; Fu, Suiyan; Wang, Yongfu; Ren, Jie;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028500

charge exchange; lifetime; ring current decay; Van Allen Probes

Ring Current Decay During Geomagnetic Storm Recovery Phase: Comparison Between RBSP Observations and Theoretical Modeling

Ring current decay during storm recovery phase may be affected by different loss processes. In this study, we have investigated the lifetimes of ring current ions (H+ and O+) of energies from 1 keV to several hundred keV at L shell from 3 to 6 during the storm recovery phase through a statistical survey. The observational data of 48 geomagnetic storms from March 2013 to May 2019 are collected based on Van Allen Probe observations. We find that (1) the observed lifetimes of H+ and O+ in general increase with L shell and (2) ...

Chen, Ao; Yue, Chao; Chen, HongFei; Zong, Qiugang; Fu, Suiyan; Wang, Yongfu; Ren, Jie;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028500

charge exchange; lifetime; ring current decay; Van Allen Probes

Statistical Study of Chorus Modulations by Background Magnetic Field and Plasma Density

In this study, we use observations of THEMIS and Van Allen Probes to statistically study the modulations of chorus emissions by variations of background magnetic field and plasma density in the ultra low frequency range. The modulation events are identified automatically and divided into three types according to whether the chorus intensity correlates to the variations of the magnetic field only (Type B), plasma density only (Type N), or both (Type NB). For the THEMIS observations, the occurrences of the Types B and N are la ...

Xia, Zhiyang; Chen, Lunjin; Li, Wen;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL089344

Van Allen Probes

Alpha Transmitter Signal Reflection and Triggered Emissions

Russian Alpha radio navigation system (RSDN-20) emits F1 = 11.9 kHz signals into the magnetosphere which propagate as whistler mode waves. Observed by waveform continuous burst mode from Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on Van Allen Probes, a case is presented and featured with ducted propagation, multiple reflections, and triggered emissions. Both risers and fallers appear in the triggered emissions. We use a ray tracing method to demonstrate ducted propagation, which has a s ...

Gu, Wenyao; Chen, Lunjin; Xia, Zhiyang; An, Xin; Horne, Richard;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL090165

VLF transmitter; ducted propagation; triggered emission; Van Allen Probes

Long-Term Dropout of Relativistic Electrons in the Outer Radiation Belt During Two Sequential Geomagnetic Storms

On 31 January 2016, the flux of >2 MeV electrons observed by Geostationary Operational Environmental Satellite (GOES)-13 dropped to the background level during a minor storm main phase (−48 nT). Then, a second storm (−53 nT) occurred on 2 February; during the 3 days after its main phase, the flux remained at background level. Using data from various instruments on the GOES, Polar Operational Environmental Satellites (POES), Radiation Belt Storm Probes (RBSP), Meteor-M2, and Fengyun-series spacecraft, we study this long ...

Wu, H.; Chen, T.; Kalegaev, V.; Panasyuk, M.; Vlasova, N.; Duan, S.; Zhang, X.; He, Z.; Luo, J.; Wang, C.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028098

Radiation belt; relativistic electron dropout; Geomagnetic storm; Van Allen Probes

Statistical Study on Locally Generated High-Frequency Plasmaspheric Hiss and Its Effect on Suprathermal Electrons: Van Allen Probes Observation and Quasi-linear Simulation

The local generation of high-frequency plasmaspheric hiss has recently been reported by a case study (He et al., 2019, https://doi.org/10.1029/2018GL081578). In this research, we perform statistics of global distributions of the locally generated high-frequency plasmaspheric hiss (LHFPH) for different levels of substorm activity, using 6-year observational data from Van Allen Probes. The statistics find that the LHFPH amplitude presents a strong magnetic local time (MLT) asymmetry and highly depends on substorm activity, and ...

He, Zhaoguo; Yu, Jiang; Chen, Lunjin; Xia, Zhiyang; Wang, Wenrui; Li, Kun; Cui, Jun;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028526

Van Allen Probes

Statistical Evidence for EMIC Wave Excitation Driven by Substorm Injection and Enhanced Solar Wind Pressure in the Earth s Magnetosphere: Two Different EMIC Wave Sources

Substorm injection and solar wind dynamic pressure have long been considered as two main drivers of electromagnetic ion cyclotron (EMIC) wave excitation, but clear observational evidence is still lacking. With Van Allen Probes data from 2012–2017, we have investigated the roles of the two EMIC wave drivers separately, by using time-modified AE+ and . Both the occurrence rate and magnetic amplitude of waves significantly increase with the enhancement of each index. During large AE+, EMIC waves are mainly generated in the du ...

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

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL090275

EMIC wave; wave excitation; source region; substorm injection; solar wind dynamic pressure; Earth s magnetosphere; Van Allen Probes

Lower-Band “Monochromatic” Chorus Riser Subelement/Wave Packet Observations

Three lower-band (f < 0.5 fce) chorus riser elements detected in the dayside generation region were studied in detail using the Van Allen Probe data. Two subelements/wave packets within each riser were examined for their wave “frequency” constancy within seven consecutive wave cycles. The seven wave cycles contained the maximum amplitudes of the subelements/packets. Maximum variance B1 zero crossings were used for the identification of wave cycle start and stop times. It is found that the frequency is constant to with ...

Tsurutani, Bruce; Chen, Rui; Gao, Xinliang; Lu, Quanming; Pickett, Jolene; Lakhina, Gurbax; Sen, Abhijit; Hajra, Rajkumar; Park, Sang; Falkowski, Barbara;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028090

chorus coherency; chorus subelement monochromaticity; a modified theory needed; Van Allen Probes

Origin of Electron Boomerang Stripes: Localized ULF Wave-Particle Interactions

Ultralow frequency (ULF) wave-particle interactions play a significant role in the radiation belt dynamic process, during which drift resonance can accelerate and transport energetic electrons in the outer radiation belt. Observations of wave-electron drift resonance are characterized by quasiperiodic straight or “boomerang-shaped” stripes in the pitch angle spectrogram. Here we present an ULF wave event on 1 December 2015, during which both kinds stripes were observed by Van Allen Probes A and B, respectively. Using the ...

Zhao, X.; Hao, Y.; Zong, Q.-G.; Zhou, X.-Z.; Yue, Chao; Chen, X.; Liu, Y.; Blake, J.; Claudepierre, S.; Reeves, G.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL087960

boomerang-shaped stripes; ULF waves; drift resonance; time of flight; Van Allen Probes

A Short-lived Three-Belt Structure for sub-MeV Electrons in the Van Allen Belts: Time Scale and Energy Dependence

In this study we focus on the radiation belt dynamics driven by the geomagnetic storms during September 2017. Besides the long-lasting three-belt structures of ultrarelativistic electrons (>2 MeV, existing for tens of days), which has been studied intensively during the Van Allen Probe era, it is found that magnetospheric electrons of hundreds of keVs can also have three-belt structures at similar L extent during storm time. Measurements of 500–800 keV electrons from MagEIS instrument onboard Van Allen Probes show double- ...

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

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028031

storage ring; three-belt structure; hiss wave; electron lifetime; Radial Transport; Van Allen Probes

Electron-Driven Magnetic Dip Embedded Within the Proton-Driven Magnetic Dip and the Related Echoes of Butterfly Distribution of Relativistic Electrons

In this study, a magnetic dip event in which a small-scale magnetic dip is embedded within a large-scale magnetic dip is analyzed based on the observations of the Van Allen Probes. The small-scale dip is contributed by a sharp electron injection at the energy range of 1 to 10 keV, but the large-scale dip is contributed by a smooth proton injection at the energy range higher than 10 keV. The formation of dip caused by the suprathermal electrons is supported by the self-consistent magnetic model. Moreover, the echoes of bu ...

Zhu, Hui; Chen, Lunjin; Xia, Zhiyang;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088983

magnetic dips; echoes of butterfly distributions; ring current-radiation belt coupling; Van Allen Probes

Simultaneous Observations of Localized and Global Drift Resonance

In this study, we present Van Allen Probe observations showing that seed (hundreds of keV) and core ( 1 MeV) electrons can resonate with ultra-low-frequency (ULF) wave modes with distinctive m values simultaneously. An unusual electron energy spectrogram with double-banded resonant structure was recorded by energetic particle, composition, and thermal plasma (ECT)-magnetic electron ion spectrometer (MagEIS) and, meanwhile, boomerang stripes in pitch angle spectrogram appeared at the lower energy band. A localized drift reson ...

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

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088019

drift resonance; ULF waves; Radiation Belt Dynamics; boomerang stripes; azimuthal wave number; multiple resonances; Van Allen Probes

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

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

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 harmonic ban ...

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

YEAR: 2020     DOI: https://doi.org/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

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 using the ...

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

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027776

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

Global Simulation of Electron Cyclotron Harmonic Wave Instability in a Storm-Time Magnetosphere

Abstract Electron cyclotron harmonic (ECH) waves are electrostatic emissions between the ECHs and play a dominant role for precipitating energetic electrons in the magnetotail. Statistically, the ECH wave intensity is stronger at nightside and dawnside than at dayside and duskside. In this study, we, for the first time, simulate the global ECH wave evolution during a geomagnetic storm event using Ring current Atmosphere interactions Model with Self-Consistent Magnetic field (RAM-SCB) combined with a linear growth rate solver ...

Liu, Xu; Chen, Lunjin; Engel, Miles; Jordanova, Vania;

YEAR: 2020     DOI: https://doi.org/10.1029/2019GL086368

ECH wave global instability; RAM-SCB model; Geomagnetic storm; 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



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