Bibliography





Van Allen Probes Bibliography is from August 2012 through September 2021

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Found 41 entries in the Bibliography.


Showing entries from 1 through 41


2021

Van Allen Probes Observations of Multi-MeV Electron Drift-Periodic Flux Oscillations in Earth’s Outer Radiation Belt During the March 2017 Event

Abstract Radiation belt electrons undergo frequent acceleration, transport, and loss processes under various physical mechanisms. One of the most prevalent mechanisms is radial diffusion, caused by the resonant interactions between energetic electrons and ULF waves in the Pc4-5 band. An indication of this resonant interaction is believed to be the appearance of periodic flux oscillations. In this study, we report long-lasting, drift-periodic flux oscillations of relativistic and ultrarelativistic electrons with energies up t ...

Zhao, Hong; Sarris, Theodore; Li, Xinlin; Weiner, Max; Huckabee, Isabela; Baker, Daniel; Jaynes, Allison; Kanekal, Shrikanth; Elkington, Scot; Barani, Mohammad; Tu, Weichao; Liu, Wenlong; Zhang, Dianjun; Hartinger, Michael;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2021

YEAR: 2021     DOI: https://doi.org/10.1029/2021JA029284

Radiation belt; multi-MeV electrons; radial diffusion; ULF waves; Wave-particle interaction; Phase space density radial gradient; 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;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2021

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.;

Published by: Geophysical Research Letters      Published on: 05/2021

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

Modeling the Dynamics of Radiation Belt Electrons with Source and Loss Driven by the Solar Wind

Abstract A radial diffusion model directly driven by the solar wind is developed to reproduce MeV electron variations between L=2-12 (L is L* in this study) from October 2012 to April 2015. The radial diffusion coefficient, internal source rate, quick loss due to EMIC waves, and slow loss due to hiss waves are all expressed in terms of the solar wind speed, dynamic pressure, and interplanetary magnetic field (IMF). The model achieves a prediction efficiency (PE) of 0.45 at L=5 and 0.51 at L=4 after converting the electron ph ...

Xiang, Zheng; Li, Xinlin; Kapali, Sudha; Gannon, Jennifer; Ni, Binbin; Zhao, Hong; Zhang, Kun; Khoo, Leng;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2021

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028988

Radiation belt; Solar wind; flux prediction; radial diffusion; magnetopause shadowing; wave-particle interactions; Van Allen Probes

Global distribution of reversed energy spectra of ring current protons based on Van Allen Probes observations

Abstract Energy spectra of ring current protons are crucial to understanding the ring current dynamics. Based on high-quality Van Allen Probes RBSPICE measurements, we investigate the global distribution of the reversed proton energy spectra using the 2013-2019 RBSPICE datasets. The reversed proton energy spectra are characterized by the distinct flux minima around 50 - 100 keV and flux maxima around 200 - 400 keV. Our results show that the reversed proton energy spectrum is prevalent inside the plasmasphere, with the occurr ...

Juan, Yi; Song, Fu; Binbin, Ni; Xudong, Gu; Hua, Man; Xiang, Zheng; Cao, Xing; Shi, Run; Zhao, Yiwen;

Published by: Geophysical Research Letters      Published on: 01/2021

YEAR: 2021     DOI: https://doi.org/10.1029/2020GL091559

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.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2020

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

New Insights From Long-Term Measurements of Inner Belt Protons (10s of MeV) by SAMPEX, POES, Van Allen Probes, and Simulation Results

The Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission provided long-term measurements of 10s of megaelectron volt (MeV) inner belt (L < 2) protons (1992–2009) as did the Polar-orbiting Operational Environmental Satellite-18 (POES-18, 2005 to present). These long-term measurements at low-Earth orbit (LEO) showed clear solar cycle variations which anticorrelate with sunspot number. However, the magnitude of the variation is much greater than the solar cycle variation of galactic cosmic rays (>GeV) tha ...

Li, Xinlin; Xiang, Zheng; Zhang, Kun; Khoo, Lengying; Zhao, Hong; Baker, Daniel; Temerin, Michael;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2020

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028198

Inner radiation belt; Inner Belt Proton; Solar cycle variation; Cosmic rays; neutron monitor; Low Earth Orbit satellite; Van Allen Probes

Dynamics of Energetic Electrons in the Slot Region During Geomagnetically Quiet Times: Losses Due to Wave-Particle Interactions Versus a Source From Cosmic Ray Albedo Neutron Decay (CRAND)

Earth s slot region, lying between the outer and inner radiation belts, has been identified as due to a balance between inward radial diffusion and pitch angle (PA) scattering induced by waves. However, recent satellite observations and modeling studies indicate that cosmic ray albedo neutron decay (CRAND) may also play a significant role in energetic electron dynamics in the slot region. In this study, using a drift-diffusion-source model, we investigate the relative contribution of all significant waves and CRAND to the dy ...

Xiang, Zheng; Li, Xinlin; Ni, Binbin; Temerin, M.; Zhao, Hong; Zhang, Kun; Khoo, Leng;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2020

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028042

Slot region; Wave-particle interaction; CRAND; energetic electrons; 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.;

Published by: Geophysical Research Letters      Published on: 07/2020

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

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

Simulations of Electron Flux Oscillations as Observed by MagEIS in Response to Broadband ULF Waves

Coherent electron flux oscillations of hundreds of keV are often observed by the Van Allen Probes in the magnetosphere during quiet times in association with ultralow frequency (ULF) waves. They are observed in the form of periodic flux fluctuations, with a drift frequency that is energy dependent, but are not associated with drift echoes following storm- or substorm-related energetic particle injections. Instead, they are associated with the resonant interaction of electrons with ULF waves and are an indication of ongoing e ...

Sarris, Theodore; Li, Xinlin; Temerin, Michael; Zhao, Hong; Khoo, Leng; Turner, Drew; Liu, Wenlong; Claudepierre, Seth;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2020

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027798

electron flux oscillations; ULF waves; Magnetosphere; Radiation belts; radial diffusion; particle tracing simulations; 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.; Fu, S; Blake, J.; Reeves, G.; Claudepierre, S.;

Published by: Geophysical Research Letters      Published on: 05/2020

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 Role of the Dynamic Plasmapause in Outer Radiation Belt Electron Flux Enhancement

Abstract The plasmasphere is a highly dynamic toroidal region of cold, dense plasma around Earth. Plasma waves exist both inside and outside this region and can contribute to the loss and acceleration of high energy outer radiation belt electrons. Early observational studies found an apparent correlation on long time scales between the observed inner edge of the outer radiation belt and the modeled innermost plasmapause location. More recent work using high-resolution Van Allen Probes data has found a more complex relationsh ...

Bruff, M.; Jaynes, A.; Zhao, H.; Goldstein, J.; Malaspina, D.; Baker, D.; Kanekal, S.; Spence, H.; Reeves, G.;

Published by: Geophysical Research Letters      Published on: 03/2020

YEAR: 2020     DOI: 10.1029/2020GL086991

Plasmapause; outer radiation belt; Magnetosphere; chorus waves; Van Allen Probes

Upper Limit of Electron Fluxes Observed in the Radiation Belts

Radiation belt electrons have a complicated relationship with geomagnetic activity. We select electron measurements from 7 years of DEMETER and 6 years of Van Allen Probes data during geomagnetic storms to conduct statistical analysis focusing on the correlation between electron flux and Dst index. We report, for the first time, an upper limit of electron fluxes observed by both satellites throughout the inner and outer belts across a wide energy range from ?100s keV to multi-MeV. The upper flux limit is determined at diffe ...

Zhang, Kun; Li, Xinlin; Zhao, Hong; Xiang, Zheng; Khoo, Leng; Zhang, Wenxun; Hogan, Benjamin; Temerin, Michael;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028511

electron; Radiation belt; statistics; upper limit; Van Allen Probes

2019

Comparison of Van Allen Probes Energetic Electron Data with Corresponding GOES-15 Measurements: 2012-2018

Baker, D.N.; Zhao, H.; Li, X.; Kanekal, S.G.; Jaynes, A.N.; Kress, B.T.; Rodriguez, J.V.; Singer, H.J.; Claudepierre, S.G.; Fennell, J.F.; Hoxie, V.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2019

YEAR: 2019     DOI: 10.1029/2019JA027331

energetic particles; Magnetosphere:Inner; Magnetospheric configuration; Radiation belts; Space weather; Van Allen Probes

How Sudden, Intense Energetic Electron Enhancements Correlate With the Innermost Plasmapause Locations Under Various Solar Wind Drivers and Geomagnetic Conditions

In this report, the relationship between innermost plasmapause locations (Lpp) and initial electron enhancements during both storm and nonstorm (Dst > -30 nT) periods are examined using data from the Van Allen Probes. The geomagnetic storms are classified into coronal mass ejection (CME)-driven and corotating interaction region (CIR)-driven storms to explore their influences on the initial electron enhancements, respectively. We also study nonstorm time electron enhancements and observe frequent, sudden (within two consecuti ...

Khoo, L.-Y.; Li, X.; Zhao, H.; Chu, X.; Xiang, Z.; Zhang, K.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2019

YEAR: 2019     DOI: 10.1029/2019JA027412

energetic electron enhancements; Plasmapause; Radiation Belt Dynamics; Van Allen Probes

Identifying STEVE\textquoterights Magnetospheric Driver Using Conjugate Observations in the Magnetosphere and on the Ground

The magnetospheric driver of strong thermal emission velocity enhancement (STEVE) is investigated using conjugate observations when Van Allen Probes\textquoteright footprint directly crossed both STEVE and stable red aurora (SAR) arc. In the ionosphere, STEVE is associated with subauroral ion drift features, including electron temperature peak, density gradient, and westward ion flow. The SAR arc at lower latitudes corresponds to regions inside the plasmapause with isotropic plasma heating, which causes redline-only SAR emis ...

Chu, Xiangning; Malaspina, David; Gallardo-Lacourt, Bea; Liang, Jun; Andersson, Laila; Ma, Qianli; Artemyev, Anton; Liu, Jiang; Ergun, Robert; Thaller, Scott; Akbari, Hassanali; Zhao, Hong; Larsen, Brian; Reeves, Geoffrey; Wygant, John; Breneman, Aaron; Tian, Sheng; Connors, Martin; Donovan, Eric; Archer, William; MacDonald, Elizabeth;

Published by: Geophysical Research Letters      Published on: 11/2019

YEAR: 2019     DOI: 10.1029/2019GL082789

aurora; kinetic Alfven wave; Plasmapause; STEVE; subauroral ion drift; table red auroral arc; Van Allen Probes

On the Acceleration Mechanism of Ultrarelativistic Electrons in the Center of the Outer Radiation Belt: A Statistical Study

Using energetic particle and wave measurements from the Van Allen Probes, Polar Orbiting Environmental Satellites (POES), and Geostationary Operational Environmental Satellite (GOES), the acceleration mechanism of ultrarelativistic electrons (>3 MeV) in the center of the outer radiation belt is investigated statistically. A superposed epoch analysis is conducted using 19 storms, which caused flux enhancements of 1.8\textendash7.7 MeV electrons. The evolution of electron phase space density radial profile suggests an energy-d ...

Zhao, H.; Baker, D.N.; Li, X.; Malaspina, D.M.; Jaynes, A.N.; Kanekal, S.G.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2019

YEAR: 2019     DOI: 10.1029/2019JA027111

Acceleration mechanism; Inward radial diffusion; Local Acceleration; Phase space density; Radiation belts; ultrarelativistic electrons; Van Allen Probes

Global Occurrences of Auroral Kilometric Radiation Related to Suprathermal Electrons in Radiation Belts

Auroral kilometric radiation (AKR) can potentially produce serious damage to space-borne systems by accelerating trapped radiation belt electrons to relativistic energies. Here we examine the global occurrences of AKR emissions in radiation belts based on Van Allen Probes observations from 1 October 2012 to 31 December 2016. The statistical results (1,848 events in total) show that AKR covers a broad region of L= 3\textendash6.5 and 00\textendash24 magnetic local time (MLT), with a higher occurrence on the nightside (20\text ...

Zhao, Wanli; Liu, Si; Zhang, Sai; Zhou, Qinghua; Yang, Chang; He, Yihua; Gao, Zhonglei; Xiao, Fuliang;

Published by: Geophysical Research Letters      Published on: 07/2019

YEAR: 2019     DOI: 10.1029/2019GL083944

Auroral kilometric radiation; global occurrence; Radiation belt; suprathermal electron flux enhancenments; Van Allen Probes

Wave Normal Angle Distribution of Fast Magnetosonic Waves: A Survey of Van Allen Probes EMFISIS Observations

Using Van Allen Probe Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) wave observations from September 2012 to May 2018, we statistically investigate the distributions of power-weighted wave normal angle (WNA) of fast magnetosonic (MS) waves from L = 2\textendash6 within \textpm15\textdegree geomagnetic latitudes. The spatial distributions show that the MS WNAs are mainly confined within 87\textendash89\textdegree near the geomagnetic equator and decrease with increasing magnetic latitude. Furth ...

Zou, Zhengyang; Zuo, Pingbing; Ni, Binbin; Wei, Fengsi; Zhao, Zhengyu; Cao, Xing; Fu, Song; Gu, Xudong;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2019

YEAR: 2019     DOI: 10.1029/2019JA026556

Empirical Model; Fast Magnetosonic Waves; latitudinal dependence; power-weighted wave normal angles; spatial distributions; Van Allen Probes

Characterization and Evolution of Radiation Belt Electron Energy Spectra Based on the Van Allen Probes Measurements

Based on the measurements of ~100-keV to 10-MeV electrons from the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron and Proton Telescope (REPT) on the Van Allen Probes, the radiation belt electron energy spectra characterization and evolution have been investigated systematically. The results show that the majority of radiation belt electron energy spectra can be represented by one of three types of distributions: exponential, power law, and bump-on-tail (BOT). The exponential spectra are generally domin ...

Zhao, H.; Johnston, W.R.; Baker, D.N.; Li, X.; Ni, B.; Jaynes, A.N.; Kanekal, S.G.; Blake, J.B.; Claudepierre, S.G.; Reeves, G.D.; Boyd, A.J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2019

YEAR: 2019     DOI: 10.1029/2019JA026697

Bump-on-tail energy spectrum; Energy spectrum; Exponential energy spectrum; Plasmapause; Power law energy spectrum; radiation belt electrons; Van Allen Probes

The Effects of Geomagnetic Storms and Solar Wind Conditions on the Ultrarelativistic Electron Flux Enhancements

Using data from the Relativistic Electron Proton Telescope on the Van Allen Probes, the effects of geomagnetic storms and solar wind conditions on the ultrarelativistic electron (E > ~3 MeV) flux enhancements in the outer radiation belt, especially regarding their energy dependence, are investigated. It is showed that, statistically, more intense geomagnetic storms are indeed more likely to cause flux enhancements of ~1.8- to 7.7-MeV electrons, though large variations exist. As the electron energy gets higher, the probabilit ...

Zhao, H.; Baker, D.; Li, X.; Jaynes, A.; Kanekal, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2019

YEAR: 2019     DOI: 10.1029/2018JA026257

Acceleration mechanism; Geomagnetic storms; Radiation belt; solar wind conditions; ultrarelativistic electrons; Van Allen Probes

Multiyear Measurements of Radiation Belt Electrons: Acceleration, Transport, and Loss

In addition to clarifying morphological structures of the Earth\textquoterights radiation belts, it has also been a major achievement of the Van Allen Probes mission to understand more thoroughly how highly relativistic and ultrarelativistic electrons are accelerated deep inside the radiation belts. Prior studies have demonstrated that electrons up to energies of 10 megaelectron volts (MeV) can be produced over broad regions of the outer Van Allen zone on timescales of minutes to a few hours. It often is seen that geomagneti ...

Baker, Daniel; Hoxie, Vaughn; Zhao, Hong; Jaynes, Allison; Kanekal, Shri; Li, Xinlin; Elkington, Scot;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2019

YEAR: 2019     DOI: 10.1029/2018JA026259

convection electric field; Energetic particle deep penetration; Low L Region; Radiation belts; Van Allen Probes

2018

On the Initial Enhancement of Energetic Electrons and the Innermost Plasmapause Locations: CME-Driven Storm Periods

Using Van Allen Probes\textquoteright observations and established plasmapause location (Lpp) models, we investigate the relationship between the location of the initial enhancement (IE) of energetic electrons and the innermost (among all magnetic local time sectors) Lpp over five intense storm periods. Our study reveals that the IE events for 30 keV to 2MeV electrons always occurred outside of the innermost Lpp. On average, the inner extent of the IE events (LIE) for <800 keV electrons was closer to the innermost Lpp when c ...

Khoo, Leng; Li, Xinlin; Zhao, Hong; Sarris, Theodore; Xiang, Zheng; Zhang, Kun; Kellerman, Adam; Blake, Bernard;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2018

YEAR: 2018     DOI: 10.1029/2018JA026074

energetic electron; enhancements; plasmasphere; Radiation belt; Van Allen Probes

The Acceleration of Ultrarelativistic Electrons During a Small to Moderate Storm of 21 April 2017

The ultrarelativistic electrons (E > ~3 MeV) in the outer radiation belt received limited attention in the past due to sparse measurements. Nowadays, the Van Allen Probes measurements of ultrarelativistic electrons with high energy resolution provide an unprecedented opportunity to study the dynamics of this population. In this study, using data from the Van Allen Probes, we report significant flux enhancements of ultrarelativistic electrons with energies up to 7.7 MeV during a small to moderate geomagnetic storm. The underl ...

Zhao, H.; Baker, D.; Li, X.; Jaynes, A.; Kanekal, S.;

Published by: Geophysical Research Letters      Published on: 06/2018

YEAR: 2018     DOI: 10.1029/2018GL078582

Energy-dependent acceleration; Geomagnetic storms; Inward radial diffusion; Local Acceleration; Radiation belts; Ultra-relativistic electrons; Van Allen Probes

Observation of Oblique Lower Band Chorus Generated by Nonlinear Three-Wave Interaction

Oblique whistler mode waves have been suggested to play an important role in radiation belt electron dynamics. Recently, Fu et al. [2017] proposed that highly oblique lower band whistler waves could be generated by nonlinear three-wave resonance. Here we present the first observational evidence of such process, using Van Allen Probes data, where an oblique lower band chorus wave is generated by two quasi-parallel waves through nonlinear three-wave interaction. The wave resonance condition is satisfied even in the presence of ...

Teng, S.; Zhao, J.; Tao, X.; Wang, S.; Reeves, G.;

Published by: Geophysical Research Letters      Published on: 06/2018

YEAR: 2018     DOI: 10.1029/2018GL078765

Oblique lower band chorus; radiation belt physics; Van Allen Probes; wave particle interaction; wave-wave interaction

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.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2018

YEAR: 2018     DOI: 10.1029/2018JA025277

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

Storm-time evolution of outer radiation belt relativistic electrons by a nearly continuous distribution of chorus

During the 13-14 November 2012 storm, Van Allen Probe A simultaneously observed a 10-h period of enhanced chorus (including quasi-parallel and oblique propagation components) and relativistic electron fluxes over a broad range of L = 3-6 and MLT=2 - 10 within a complete orbit cycle. By adopting a Gaussian fit to the observed wave spectra, we obtain the wave parameters and calculate the bounce-averaged diffusion coefficients. We solve the Fokker-Planck diffusion equation to simulate flux evolutions of relativistic (1.8-4.2 Me ...

Yang, Chang; Xiao, Fuliang; He, Yihua; Liu, Si; Zhou, Qinghua; Guo, Mingyue; Zhao, Wanli;

Published by: Geophysical Research Letters      Published on: 02/2018

YEAR: 2018     DOI: 10.1002/2017GL075894

energetic electron; Geomagnetic storm; outer radiation belt; Van Allen Probes; Wave-particle interaction; whistler-mode chorus wave

2017

Van Allen Probes measurements of energetic particle deep penetration into the low L region (L<4) during the storm on 8 April 2016

Using measurements from the Van Allen Probes, a penetration event of 10s \textendash 100s of keV electrons and 10s of keV protons into the low L-shells (L<4) is studied. Timing and magnetic local time (MLT) differences of energetic particle deep penetration are unveiled and underlying physical processes are examined. During this event, both proton and electron penetrations are MLT-asymmetric. The observed MLT difference of proton penetration is consistent with convection of plasma sheet protons, suggesting enhanced convectio ...

Zhao, H.; Baker, D.; Califf, S.; Li, X.; Jaynes, A.; Leonard, T.; Kanekal, S.; Blake, J.; Fennell, J.; Claudepierre, S.; Turner, D.; Reeves, G.; Spence, H.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2017

YEAR: 2017     DOI: 10.1002/2017JA024558

On the Relationship Between Electron Flux Oscillations and ULF Wave-Driven Radial Transport

The objective of this study is to investigate the relationship between the levels of electron flux oscillations and radial diffusion for different Phase Space Density (PSD) gradients, through observation and particle tracing simulations under the effect of model Ultra Low Frequency (ULF) fluctuations. This investigation aims to demonstrate that electron flux oscillation is associated with and could be used as an indicator of ongoing radial diffusion. To this direction, flux oscillations are observed through the Van Allen Pro ...

Sarris, Theodore; Li, Xinlin; Temerin, Michael; Zhao, Hong; Califf, Sam; Liu, Wenlong; Ergun, Robert;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2017

YEAR: 2017     DOI: 10.1002/2016JA023741

Flux Oscillations; MAGEis; EMFISIS; EFW; Phase space density; radial diffusion; Radiation belts; Van Allen Probes

The role of the convection electric field in filling the slot region between the inner and outer radiation belts

The Van Allen Probes have reported frequent flux enhancements of 100s keV electrons in the slot region, with lower energy electrons exhibiting more dynamic behavior at lower L shells. Also, in situ electric field measurements from the Combined Release and Radiation Effects Satellite, Time History of Events and Macroscale Interactions during Substorms (THEMIS), and the Van Allen Probes have provided evidence for large-scale electric fields at low L shells during active times. We study an event on 19 February 2014 where hundre ...

Califf, S.; Li, X.; Zhao, H.; Kellerman, A.; Sarris, T.; Jaynes, A.; Malaspina, D.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 02/2017

YEAR: 2017     DOI: 10.1002/2016JA023657

convection; electric field; electrons; Slot region; Van Allen Probes

2016

Combined Scattering Loss of Radiation Belt Relativistic Electrons by Simultaneous Three-band EMIC Waves: A Case Study

Multiband electromagnetic ion cyclotron (EMIC) waves can drive efficient scattering loss of radiation belt relativistic electrons. However, it is statistically uncommon to capture the three bands of EMIC waves concurrently. Utilizing data from the Electric and Magnetic Field Instrument Suite and Integrated Science magnetometer onboard Van Allen Probe A, we report the simultaneous presence of three (H+, He+, and O+) emission bands in an EMIC wave event, which provides an opportunity to look into the combined scattering effect ...

He, Fengming; Cao, Xing; Ni, Binbin; Xiang, Zheng; Zhou, Chen; Gu, Xudong; Zhao, Zhengyu; Shi, Run; Wang, Qi;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2016

YEAR: 2016     DOI: 10.1002/2016JA022483

combined scattering rates; electromagnetic ion cyclotron waves; loss timescales; radiation belt relativistic electrons; resonant wave-particle interactions; Van Allen Probes

Large-amplitude electric fields in the inner magnetosphere: Van Allen Probes observations of subauroral polarization streams

The subauroral polarization stream (SAPS) is an important magnetosphere-ionosphere (MI) coupling phenomenon that impacts a range of particle populations in the inner magnetosphere. SAPS studies often emphasize ionospheric signatures of fast westward flows, but the equatorial magnetosphere is also affected through strong radial electric fields in the dusk sector. This study focuses on a period of steady southward interplanetary magnetic field (IMF) during the 29 June 2013 geomagnetic storm where the Van Allen Probes observe a ...

Califf, S.; Li, X.; Wolf, R.; Zhao, H.; Jaynes, A.; Wilder, F.; Malaspina, D.; Redmon, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2016

YEAR: 2016     DOI: 10.1002/2015JA022252

electric field; injection; SAPS; subauroral; Van Allen Probes

Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements

Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; a ...

Zhao, H.; Li, X.; Baker, D.; Claudepierre, S.; Fennell, J.; Blake, J.; Larsen, B.; Skoug, R.; Funsten, H.; Friedel, R.; Reeves, G.; Spence, H.; Mitchell, D.; Lanzerotti, L.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2016

YEAR: 2016     DOI: 10.1002/2016JA022358

deep injections; Geomagnetic storms; ring current; ring current energy content; ring current electrons; Van Allen Probes

2015

Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales

To improve our understanding of the role of electromagnetic ion cyclotron (EMIC) waves in radiation belt electron dynamics, we perform a comprehensive analysis of EMIC wave-induced resonant scattering of outer zone relativistic (>0.5 MeV) electrons and resultant electron loss time scales with respect to EMIC wave band, L shell, and wave normal angle model. The results demonstrate that while H+-band EMIC waves dominate the scattering losses of ~1\textendash4 MeV outer zone relativistic electrons, it is He+-band and O+-band wa ...

Ni, Binbin; Cao, Xing; Zou, Zhengyang; Zhou, Chen; Gu, Xudong; Bortnik, Jacob; Zhang, Jichun; Fu, Song; Zhao, Zhengyu; Shi, Run; Xie, Lun;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2015

YEAR: 2015     DOI: 10.1002/2015JA021466

electron loss time scales; EMIC waves; outer radiation belt; relativistic electrons; resonant wave-particle interactions

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

Enabled by the comprehensive measurements from the MagEIS, HOPE, and RBSPICE instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher energy protons. During the storm main phase, ions with energies < 50 keV contribute m ...

Zhao, H.; Li, X.; Baker, D.; Fennell, J.; Blake, J.; Larsen, B.; Skoug, R.; Funsten, H.; Friedel, R.; Reeves, G.; Spence, H.; Mitchell, D.; Lanzerotti, L.; Rodriguez, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2015

YEAR: 2015     DOI: 10.1002/2015JA021533

Geomagnetic storms; Ring current energy content; Ring current ions; The DPS relation; The Dst index; Van Allen Probes

Variability of the pitch angle distribution of radiation belt ultra-relativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Fifteen months of pitch angle resolved Van Allen Probes REPT measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution (PAD) of radiation belt ultra-relativistic (>2 MeV) electrons during storm conditions and during the long-term post-storm decay. By modeling the ultra-relativistic electron pitch angle distribution as sinn α, where α is the equatorial pitch angle, we examine the spatio-temporal variations of the n-value. The results show that in ge ...

Ni, Binbin; Zou, Zhengyang; Gu, Xudong; Zhou, Chen; Thorne, Richard; Bortnik, Jacob; Shi, Run; Zhao, Zhengyu; Baker, Daniel; Kanekal, Shrikhanth; Spence, Harlan; Reeves, Geoffrey; Li, Xinlin;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2015

YEAR: 2015     DOI: 10.1002/2015JA021065

adiation belt ultra-relativistic electrons; decay timescales; Geomagnetic storms; Pitch angle distribution; resonant wave-particle interactions; Van Allen Probes

Bounce- and MLT-averaged diffusion coefficients in a physics-based magnetic field geometry obtained from RAM-SCB for the 17 March 2013 storm

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\textquoterights 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- ...

Zhao, Lei; Yu, Yiqun; Delzanno, Gian; Jordanova, Vania;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2015

YEAR: 2015     DOI: 10.1002/2014JA020858

diffusion coefficients; Radiation belt; ring current

2014

Characteristics of pitch angle distributions of 100 s keV electrons in the slot region and inner radiation belt

The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-art pitch-angle-resolved data from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard the Van Allen Probes, a detailed analysis of 100 s keV electron PADs below L = 4 is performed, in which the PADs is categorized into three types: normal (flux peaking at 90o), cap (exceedingly peaking narrowly around 90o ...

Zhao, H.; Li, X.; Blake, J.; Fennell, J.; Claudepierre, S.; Baker, D.; Jaynes, A.; Malaspina, D.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2014

YEAR: 2014     DOI: 10.1002/2014JA020386

energetic electrons; Inner radiation belt; Pitch angle distribution; plasmasphere; Slot region; Van Allen Probes; Wave-particle interaction

THEMIS measurements of quasi-static electric fields in the inner magnetosphere

We use four years of THEMIS double-probe measurements to offer, for the first time, a complete picture of the dawn-dusk electric field covering all local times and radial distances in the inner magnetosphere based on in situ equatorial observations. This study is motivated by the results from the CRRES mission, which revealed a local maximum in the electric field developing near Earth during storm times, rather than the expected enhancement at higher L shells that is shielded near Earth as suggested by the Volland-Stern mode ...

Califf, S.; Li, X.; Blum, L.; Jaynes, A.; Schiller, Q.; Zhao, H.; Malaspina, D.; Hartinger, M.; Wolf, R.; Rowland, D.; Wygant, J.; Bonnell, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2014

YEAR: 2014     DOI: 10.1002/2014JA020360

convection; double probe; electric field; inner magnetosphere

Peculiar pitch angle distribution of relativistic electrons in the inner radiation belt and slot region

The relativistic electrons in the inner radiation belt have received little attention in the past due to sparse measurements and unforgiving contamination from the inner belt protons. The high-quality measurements of the Magnetic Electron Ion Spectrometer instrument onboard Van Allen Probes provide a great opportunity to investigate the dynamics of relativistic electrons in the low L region. In this letter, we report the newly unveiled pitch angle distribution (PAD) of the energetic electrons with minima at 90\textdegree nea ...

Zhao, H.; Li, X.; Blake, J.; Fennell, J.; Claudepierre, S.; Baker, D.; Jaynes, A.; Malaspina, D.; Kanekal, S.;

Published by: Geophysical Research Letters      Published on: 04/2014

YEAR: 2014     DOI: 10.1002/2014GL059725

Van Allen Probes

2013

First Results from CSSWE CubeSat: Characteristics of Relativistic Electrons in the Near-Earth Environment During the October 2012 Magnetic Storms

Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board the Colorado Student Space Weather Experiment (CSSWE) CubeSat mission, which was launched into a highly inclined (65\textdegree) low Earth orbit, are analyzed along with measurements from the Relativistic Electron and Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes, which are in a low inclination (10\textdegree) geo-transfer-like orbit. Both REPT ...

Li, X.; Schiller, Q.; Blum, L.; Califf, S.; Zhao, H.; Tu, W.; Turner, D.; Gerhardt, D.; Palo, S.; Kanekal, S.; Baker, D.; Fennell, J.; Blake, J.; Looper, M.; Reeves, G.; Spence, H.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2013

YEAR: 2013     DOI: 10.1002/2013JA019342

RBSP; Van Allen Probes



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