Bibliography



Found 858 entries in the Bibliography.


Showing entries from 101 through 150


2020

Dynamic Properties of Particle Injections Inside Geosynchronous Orbit: A Multisatellite Case Study

Four closely located satellites at and inside geosynchronous orbit (GEO) provided a great opportunity to study the dynamical evolution and spatial scale of premidnight energetic particle injections inside GEO during a moderate substorm on 23 December 2016. Just following the substorm onset, the four spacecraft, a LANL satellite at GEO, the two Van Allen Probes (also called “RBSP”) at ~5.8 RE, and a THEMIS satellite at ~5.3 RE, observed substorm-related particle injections and local dipolarizations near the central meridi ...

Motoba, T.; Ohtani, S.; Claudepierre, S.; Reeves, G.; . Y. Ukhorskiy, A; Lanzerotti, L.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028215

deep particle injections; dipolarizations; substorms; localized DF; Van Allen Probes

The Impenetrable Barrier: Suppression of Chorus Wave Growth by VLF Transmitters

Rapid radiation belt recovery following storm time depletion involves local acceleration of multi-MeV electrons in nonlinear interactions with VLF chorus waves. Previous studies of an apparent impenetrable barrier at L ~ 2.8 focused on diffusion and precipitation loss mechanisms for an explanation of the sharp reduction of multi-MeV electron fluxes earthward of L ~ 3. Van Allen Probes observations for cases when the plasmasphere is contracted earthward of L ~ 3 indicate that strong coherent signals from VLF transmitter ...

Foster, John; Erickson, Philip; Omura, Yoshiharu; Baker, Daniel;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027913

Radiation belt; Plasmapause; VLF transmitters; wave-particle interactions; Electron acceleration; nonlinear VLF chorus; Van Allen Probes

Suprathermal Electron Evolution Under the Competition Between Plasmaspheric Plume Hiss Wave Heating and Collisional Cooling

Suprathermal electrons are a major heat source of ionospheric plasma. How the suprathermal electrons evolve during their bounces inside the plasmasphere is a fundamental question for the magnetosphere-ionosphere coupling. On the basis of Van Allen Probes observations and quasi-linear simulations, we present here the first quantitative study on the evolution of suprathermal electrons under the competition between Landau heating by whistler mode hiss waves and Coulomb collisional cooling by background plasma inside a plasmasph ...

Wang, Zhongshan; Su, Zhenpeng; Liu, Nigang; Dai, Guyue; Zheng, Huinan; Wang, Yuming; Wang, Shui;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL089649

magnetosphere-ionosphere coupling; whistler mode hiss waves; Landau resonance; Coulomb collisions; suprathermal electrons; ring current; 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

Quantifying the Effects of EMIC Wave Scattering and Magnetopause Shadowing in the Outer Electron Radiation Belt by Means of Data Assimilation

In this study we investigate two distinct loss mechanisms responsible for the rapid dropouts of radiation belt electrons by assimilating data from Van Allen Probes A and B and Geostationary Operational Environmental Satellites (GOES) 13 and 15 into a 3-D diffusion model. In particular, we examine the respective contribution of electromagnetic ion cyclotron (EMIC) wave scattering and magnetopause shadowing for values of the first adiabatic invariant μ ranging from 300 to 3,000 MeV G−1. We inspect the innovation vector ...

Cervantes, S.; . Y. Shprits, Y; Aseev, N.; Allison, H.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028208

data assimilation; EMIC waves; magnetopause shadowing; innovation vector; Kalman Filter; radiation belt losses; Van Allen Probes

Evidence of Nonlinear Interactions Between Magnetospheric Electron Cyclotron Harmonic Waves

Electron cyclotron harmonic (ECH) waves play an important role in the magnetosphere-ionosphere coupling. They are usually considered to be generated by the Bernstein-mode instability with electron loss cone distributions. By analyzing the Van Allen Probes wave data, we present the direct evidence of the nonlinear interactions between ECH waves in the magnetosphere. Substorm-injected electrons excite primary ECH waves in a series of structureless bands between multiples of the electron gyrofrequency. Nonlinear interactions be ...

Gao, Zhonglei; Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Jiang, Chaowei; Wei, Fengsi;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088452

ECH; wave-wave interaction; nonlinear interaction; frequency spectrum broadening; electron Bernstein mode; generalized Bernstein mode; Van Allen Probes

Ionospheric Signatures of Ring Current Ions Scattered by Magnetosonic Waves

In this letter, we present unique conjugated satellite observations of ionospheric signatures of ring current (RC) ions scattered by fast magnetosonic (MS) waves. In the plasmasphere, the Van Allen Probe in situ observed MS waves. At ionospheric altitudes, the NOAA 16 satellite at the footprint of Van Allen Probe simultaneously observed obvious enhancements of mirroring RC ions, but no obvious variations of precipitating RC ions at subauroral latitudes. Theoretical calculations of pitch angle diffusion coefficients for RC io ...

Yuan, Zhigang; Yao, Fei; Yu, Xiongdong; Ouyang, Zhihai; Huang, Shiyong;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL089032

magnetosonic waves; mirroring ions; pitch angle scatter; precipitating ions; Van Allen Probes; Ring current ions

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;

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;

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

Slot region; Wave-particle interaction; CRAND; energetic electrons; Van Allen Probes

Spatial Extent of Quasiperiodic Emissions Simultaneously Observed by Arase and Van Allen Probes on 29 November 2018

Recent availability of a considerable amount of satellite and ground-based data has allowed us to analyze rare conjugated events where extremely low and very low frequency waves from the same source region are observed in different locations. Here, we report a quasiperiodic (QP) emission, showing one-to-one correspondence, observed by three satellites in space (Arase and the Van Allen Probes) and a ground station. The main event was on 29 November 2018 from 12:06 to 13:08 UT during geomagnetically quiet times. Using the po ...

Martinez-Calderon, C.; Němec, F.; Katoh, Y.; Shiokawa, K.; Kletzing, C.; Hospodarsky, G.; Santolik, O.; Kasahara, Y.; Matsuda, S.; Kumamoto, A.; Tsuchiya, F.; Matsuoka, A.; Shoji, M.; Teramoto, M.; Kurita, S.; Miyoshi, Y.; Ozaki, M.; Nishitani, N.; Oinats, A.; Kurkin, V.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028126

VLF/ELF; spatial extent; conjugated events; ERG; RBSP; quasiperiodic emissions; Van Allen Probes

Properties of Lightning Generated Whistlers Based on Van Allen Probes Observations and Their Global Effects on Radiation Belt Electron Loss

Lightning generated whistlers (LGWs) play an important role in precipitating energetic electrons in the Earth s inner radiation belt and beyond. Wave burst data from the Van Allen Probes are used to unambiguously identify LGWs and analyze their properties at L < 4 by extending their frequencies down to ~100 Hz for the first time. The statistical results show that LGWs typically occur at frequencies from 100 Hz to 10 kHz with the major wave power below the equatorial lower hybrid resonance frequency, and their wave ampli ...

Green, A.; Li, W.; Ma, Q.; Shen, X.-C.; Bortnik, J.; Hospodarsky, G.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL089584

lightning generated whistlers; electron precipitation; Inner radiation belt; hiss; VLF transmitter waves; global distribution; Van Allen Probes

Correlations Between Dispersive Alfvén Wave Activity, Electron Energization, and Ion Outflow in the Inner Magnetosphere

Using measurements from the Van Allen Probes, we show that field-aligned fluxes of electrons energized by dispersive Alfvén waves (DAWs) are prominent in the inner magnetosphere during active conditions. These electrons have preferentially field-aligned anisotropies from 1.2 to >2 at energies ranging from tens of electron volts to several kiloelectron volts (keV), with largest values being coincident with magnetic field dipolarizations. Comparisons reveal that DAW energy densities and Poynting fluxes are strongly correlated ...

Hull, A.; Chaston, C.; Bonnell, J.; Damiano, P.; Wygant, J.; Reeves, G.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088985

dispersive Alfvén waves; field-aligned electrons; inner magnetosphere; oxygen ion outflow; Geomagnetic storms; substorms; Van Allen Probes

The Role of Hiss, Chorus, and EMIC Waves in the Modeling of the Dynamics of the Multi-MeV Radiation Belt Electrons

In this study, we performed a series of long-term and individual storm simulations with and without hiss, chorus, and electromagnetic ion cyclotron (EMIC) waves. We compared simulation results incorporating different wave modes with Van Allen Probes flux observations to illustrate how hiss and chorus waves aid EMIC waves in depleting multi-MeV electrons. We found that EMIC, hiss, and chorus waves are required to reproduce satellite measurements in our simulations. Our results indicate that hiss waves play a dominant role in ...

. Y. Drozdov, A; Usanova, M.; Hudson, M.; Allison, H.; . Y. Shprits, Y;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028282

EMIC waves; Radiation belts; Whistler waves; VERB code; Fokker-Planck diffusion equation; Van Allen Probes

Can Solar Wind Decompressive Discontinuities Suppress Magnetospheric Electromagnetic Ion Cyclotron Waves Associated With Fresh Proton Injections?

Electromagnetic ion cyclotron (EMIC) waves play an important role in the energy transfer among particles of different energies and species in the magnetosphere, whose drivers have been commonly recognized as solar wind compressions and storm/substorm proton injections. However, how the solar wind decompressions related to frequently occurring discontinuities compete with the proton injections in the evolution of EMIC waves has been rarely investigated. Here we present a complete end-to-end observation by Wind, THEMIS, and Va ...

Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; Wang, Yuming; Wang, Shui;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL090296

EMIC waves; solar wind discontinuity; storm/substorm injection; wave generation; adiabatic deceleration; inner magnetosphere; Van Allen Probes

Global Survey of Plasma Sheet Electron Precipitation due to Whistler Mode Chorus Waves in Earth s Magnetosphere

Whistler mode chorus waves can scatter plasma sheet electrons into the loss cone and produce the Earth s diffuse aurora. Van Allen Probes observed plasma sheet electron injections and intense chorus waves on 24 November 2012. We use quasilinear theory to calculate the precipitating electron fluxes, demonstrating that the chorus waves could lead to high differential energy fluxes of precipitating electrons with characteristic energies of 10–30 keV. Using this method, we calculate the precipitating electron flux from 2012 t ...

Ma, Q.; Connor, H.; Zhang, X.-J.; Li, W.; Shen, X.-C.; Gillespie, D.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Claudepierre, S.; Reeves, G.; Spence, H.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088798

Chorus wave; electron precipitation; plasma sheet electron; Van Allen Probes observation; 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

The Modulation of Plasma and Waves by Background Electron Density Irregularities in the Inner Magnetosphere

The background cold electron density plays an important role in plasma and wave dynamics. Here, we investigate an event with clear modulation of the particle fluxes and wave intensities by background electron density irregularities based on Van Allen Probes observations. The energies at the peak fluxes of protons and Helium ions of 100 eV to several keV are well correlated with the total electron density variation. Intense electromagnetic ion cyclotron (EMIC) and magnetosonic (MS) waves are simultaneously observed in the hi ...

Yue, Chao; Ma, Qianli; Jun, Chae-Woo; Bortnik, Jacob; Zong, Qiugang; Zhou, Xuzhi; Jang, Eunjin; Reeves, Geoffrey; Spence, Harlan; Wygant, John;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088855

electron density irregularities; electromagnetic ion cyclotron; magnetosonic waves; suprathermal particles; Wave-particle interaction; wave growth rate; Van Allen Probes

Electron Diffusion by Coexisting Plasmaspheric Hiss and Chorus Waves: Multisatellite Observations and Simulations

We report a rare event of intense plasmaspheric hiss and chorus waves simultaneously observed at the same L shell but different magnetic local times by Van Allen Probes and Magnetospheric Multiscale. Based on the measured waves and electron distributions, we calculate the bounce-averaged diffusion coefficients and subsequently simulate the temporal evolution of electron distributions. The simulations show that the dynamics of tens to hundreds of keV electrons are jointly controlled by hiss and chorus. The dynamics of MeV ele ...

Yu, J.; Wang, J.; . Y. Li, L; Cui, J.; Cao, J.; He, Z.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088753

electron diffusion; Plasmaspheric Hiss; chorus waves; Van Allen Probes; MMS

Outer Radiation Belt Electron Lifetime Model Based on Combined Van Allen Probes and Cluster VLF Measurements

The flux of energetic electrons in the outer radiation belt shows a high variability. The interactions of electrons with very low frequency (VLF) chorus waves play a significant role in controlling the flux variation of these particles. Quantifying the effects of these interactions is crucially important for accurately modeling the global dynamics of the outer radiation belt and to provide a comprehensive description of electron flux variations over a wide energy range (from the source population of 30 keV electrons up to th ...

Aryan, Homayon; Agapitov, Oleksiy; Artemyev, Anton; Mourenas, Didier; Balikhin, Michael; Boynton, Richard; Bortnik, Jacob;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028018

electron lifetimes; Van Allen radiation belts; chorus waves; pitch angle diffusion coefficients; Van Allen Probes; Cluster

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

Calculation of the Atomic Oxygen Fluence on the Van Allen Probes

The Van Allen Probes Mission consists of two identical spacecraft flying in highly elliptical orbits, with perigee altitudes originally near 600 km. During the low-altitude periods of the orbits, the spacecrafts are immersed in a region of high-density atomic oxygen. Atomic oxygen is known to change and degrade the properties of spacecraft surfaces (Banks et al., 2004), such as those of the Van Allen Probes Electric Field and Waves (EFW) instrument. The consistency of the sensor surfaces in EFW is important because the me ...

Schumm, G.; Bonnell, J.; Wygant, J.; Mozer, F.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027944

Van Allen Probes; atomic oxygen; Langmuir probes; DAG

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

An empirical model of the global distribution of plasmaspheric hiss based on Van Allen Probes EMFISIS measurements

Using wave measurements from the EMFISIS instrument onboard Van Allen Probes, we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss waves. To reproduce these empirical results, we establish a fitting model that is a third-order polynomial function of L-shell, magnetic local time (MLT), magnetic latitude (MLAT), and AE*. Quantitative comparisons indicate that the model s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensit ...

Wang, JingZhi; Zhu, Qi; Gu, Xudong; Fu, Song; Guo, JianGuang; Zhang, Xiaoxin; Yi, Juan; Guo, YingJie; Ni, Binbin; Xiang, Zheng;

YEAR: 2020     DOI: https://doi.org/10.26464/epp2020034

hiss; Van Allen Probes; global model

Experimental Determination of the Conditions Associated With “Zebra Stripe” Pattern Generation in the Earth s Inner Radiation Belt and Slot Region

The “zebra stripes” are peaks and valleys commonly present in the spectrograms of energetic particles trapped in the Earth s inner belt and slot region. Several theories have been proposed over the years to explain their generation, structure, and evolution. Yet, the plausibility of various theories has not been tested due to a historical lack of ground truth, including in situ electric field measurements. In this work, we leverage the new visibility offered by the database of Van Allen Probes electric drift measurements ...

Lejosne, Solène; Mozer, Forrest;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027889

zebra stripes; superposed epoch analysis; prompt penetration electric fields; Inner radiation belt; substorm; Van Allen Probes

Defining Radiation Belt Enhancement Events Based on Probability Distributions

We present a methodology to define moderate, strong, and intense space weather events based on probability distributions. We have illustrated this methodology using a long-duration, uniform data set of 1.8–3.5 MeV electron fluxes from multiple LANL geosynchronous satellite instruments, but a strength of this methodology is that it can be applied uniformly to heterogeneous data sets. It allows quantitative comparison of data sets with different energies, units, orbits, and so forth. The methodology identifies a range of ti ...

Reeves, Geoffrey; Vandegriff, Elizabeth; Niehof, Jonathan; Morley, Steven; Cunningham, Gregory; Henderson, Michael; Larsen, Brian;

YEAR: 2020     DOI: https://doi.org/10.1029/2020SW002528

Radiation belts; methods; geosynchronous; energetic particles; hazards; Solar Cycle; 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;

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

Conjugate Observations of Quasiperiodic Emissions by the Van Allen Probes Spacecraft and Ground-Based Station Kannuslehto

Whistler mode waves observed in the Earth s inner magnetosphere at frequencies between about 0.5 and 4 kHz which exhibit a nearly periodic time modulation of the wave intensity are called quasiperiodic (QP) emissions. Conjugate measurements of QP events at several different locations can be used to estimate their spatial extent and spatiotemporal variability. Results obtained using conjugate QP measurements provided by the ground-based station Kannuslehto (L≈5.5) and the Van Allen Probes spacecraft (L shells between about ...

Bezděková, B.; Němec, F.; Manninen, J.; Hospodarsky, G.; Santolik, O.; Kurth, W.; Hartley, D.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027793

Van Allen Probes

Solar Energetic Proton Access to the Near-Equatorial Inner Magnetosphere

In this study we examine the ability of protons of solar origin to access the near-equatorial inner magnetosphere. Here we examine four distinct solar proton events from 20–200 MeV, concurrent with both quiet time and storm time conditions using proton data from the ACE satellite in the solar wind upstream of Earth and data from the Relativistic Electron Proton Telescope (REPT) instrument aboard Van Allen Probes. We examine the direct flux correspondence between interplanetary space and the inner magnetosphere. Small subs ...

Filwett, Rachael; Jaynes, Allison; Baker, Daniel; Kanekal, Shrikanth; Kress, Brian; Blake, Bern;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027584

Van Allen Probes

Global Model of Whistler Mode Chorus in the Near-Equatorial Region (|λm|<  18°)

We extend our database of whistler mode chorus, based on data from seven satellites, by including ∼3 years of data from Radiation Belt Storm Probes (RBSP)-A and RBSP-B and an additional ∼6 years of data from Time History of Events and Macroscale Interactions during Substorms (THEMIS)-A, THEMIS-D, and THEMIS-E. The new database allows us to probe the near-equatorial region in detail, revealing new features. In the equatorial source region, |λm|<6°, strong wave power is most extensive in the 0.1–0.4fce bands in the r ...

Meredith, Nigel; Horne, Richard; Shen, Xiao-Chen; Li, Wen; Bortnik, Jacob;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL087311

whistler mode chorus; wave-particle interactions; Radiation belts; Van Allen Probes

Lifetimes of Relativistic Electrons as Determined From Plasmaspheric Hiss Scattering Rates Statistics: Effects of ωpe/Ωce and Wave Frequency Dependence on Geomagnetic Activity

Whistler-mode hiss waves generally determine MeV electron lifetimes inside the plasmasphere. We use Van Allen Probes measurements to provide the first comprehensive statistical survey of plasmaspheric hiss-driven quasi-linear pitch-angle diffusion rates and lifetimes of MeV electrons as a function of L*, local time, and AE index, taking into account hiss power, electron plasma frequency to gyrofrequency ratio ωpe/Ωce, hiss frequency at peak power ωm, and cross correlations of these parameters. We find that during geomagne ...

Agapitov, O.; Mourenas, D.; Artemyev, A.; Claudepierre, S.; Hospodarsky, G.; Bonnell, J.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088052

electron lifetimes; plasmasphere; hiss waves; wave-particle interactions; 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

Global ENA Imaging and In Situ Observations of Substorm Dipolarization on 10 August 2016

Abstract This paper presents the first combined use of data from Magnetospheric Multiscale (MMS), Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS), and Van Allen Probes (RBSP) to study the 10 August 2016 magnetic dipolarization. We report the first correlation of MMS tail observations with TWINS energetic neutral atom (ENA) images of the ring current (RC). We analyze 15-min, 1° TWINS 2 images in 1–50 keV energy bins. To characterize the high-altitude RC we extract peak ENA flux from L= 2.5 to 5 in the postmid ...

Goldstein, J.; Valek, P.; McComas, D.; Redfern, J.; Spence, H.; Skoug, R.; Larsen, B.; Reeves, G.; Nakamura, R.;

YEAR: 2020     DOI: 10.1029/2019JA027733

substorm dipolarization; cross-scale physics; imaging; multipoint in situ; ring current; Van Allen Probes

Simultaneous Observations of Electromagnetic Ion Cyclotron (EMIC) Waves and Pitch Angle Scattering During a Van Allen Probes Conjunction

Abstract On 22 December 2015, the two Van Allen Probes observed two sets of electromagnetic ion cyclotron (EMIC) wave bursts during a close conjunction when both Probe A and Probe B were separated by 0.57 to 0.68 RE. The EMIC waves occurred during an active period in the recovery phase of a coronal mass ejection-driven geomagnetic storm. Both spacecraft observed EMIC wave bursts that had similar spatial structure within a 1–2 min time delay. The EMIC waves occurred outside the plasmasphere, within ΔL ≈ 1–2 of the ...

Sigsbee, K.; Kletzing, C. A.; Faden, J.; Jaynes, A. N.; Reeves, G.; Jahn, J.-M.;

YEAR: 2020     DOI: 10.1029/2019JA027424

EMIC waves; Plasmapause; Proton Anisotropy; Storm Recovery Phase; Van Allen Probes; pitch angle scattering

Raytracing Study of Source Regions of Whistler Mode Wave Power Distribution Relative to the Plasmapause

Abstract A comprehensive numerical raytracing study of whistler mode wave power with the inclusion of finite background electron and ion temperature is performed in order to investigate wave power distribution in relation to the plasmapause. Both Landau damping and linear growth of whistler mode waves are taken into account using a bi-Maxwellian hot electron distribution as well as an isotropic hot electron distribution. Isotropic and bi-Maxwellian distributions yield similar results of statistical spatial wave power for fre ...

Maxworth, A.; Gołkowski, M.; Malaspina, D.; Jaynes, A.;

YEAR: 2020     DOI: 10.1029/2019JA027154

hiss; plasmasphere; Warm Plasma; Raytracing; Magnetosphere; Van Allen Probes

Bayesian Inference of Quasi-Linear Radial Diffusion Parameters using Van Allen Probes

Abstract The Van Allen radiation belts in the magnetosphere have been extensively studied using models based on radial diffusion theory, which is derived from a quasi-linear approach with prescribed inner and outer boundary conditions. The 1D diffusion model requires the knowledge of a diffusion coefficient and an electron loss timescale, which is typically parameterized in terms of various quantities such as the spatial (L) coordinate or a geomagnetic index (e.g., Kp). These terms are typically empirically derived, not dire ...

Sarma, Rakesh; Chandorkar, Mandar; Zhelavskaya, Irina; Shprits, Yuri; Drozdov, Alexander; Camporeale, Enrico;

YEAR: 2020     DOI: 10.1029/2019JA027618

radial diffusion; Magnetosphere; Bayesian inference; Van Allen radiation belt; Van Allen Probes

The Dynamics of the Inner Boundary of the Outer Radiation Belt During Geomagnetic Storms

Abstract We investigate the shapes of the inner boundary of the outer radiation belt during different geomagnetic storm phases using energetic electron observations from Van Allen Probes. The case of two consecutive but isolated storms in April 2016 shows that (a) the inner boundary, as a function of L shell and energy, exhibits a “V-shaped” form with the energetic electrons showing a kappa-like energy spectrum (electron flux steeply falling with increasing energies), whereas it is in a “S-shaped” form as the energet ...

Shi, Xiaofei; Ren, Jie; Zong, Q.;

YEAR: 2020     DOI: 10.1029/2019JA027309

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

Whistler Mode Quasiperiodic Emissions: Contrasting Van Allen Probes and DEMETER Occurrence Rates

Abstract Quasiperiodic emissions are magnetospheric whistler mode waves at frequencies between about 0.5 and 4 kHz which exhibit a nearly periodic time modulation of the wave intensity. We use large data sets of events observed by the Van Allen Probes in the equatorial region at larger radial distances and by the low-altitude DEMETER spacecraft. While Van Allen Probes observe the events at all local times and longitudes, DEMETER observations are limited nearly exclusively to the daytime and significantly less frequent at the ...

Němec, F.; Santolik, O.; Hospodarsky, G.; Hajoš, M.; Demekhov, A.; Kurth, W.; Parrot, M.; Hartley, D.;

YEAR: 2020     DOI: 10.1029/2020JA027918

quasiperiodic emissions; QP emissions; DEMETER; RBSP; Van Allen Probes

Quantifying the Effect of Plasmaspheric Hiss on the Electron Loss from the Slot Region

Abstract We present global statistical models of both wave amplitude and wave normal angle (WNA) of plasmaspheric hiss using Van Allen Probe-A observations. They utilize the time history of solar wind parameters, i.e., interplanetary magnetic field BZ and solar wind speed, and the AE index for each measurement of hiss waves as inputs. The solar wind parameter-based model generally results in higher performance than using only the AE index as an input. Both observations and model results reveal a clear dependence of hiss wave ...

Kim, Kyung-Chan; Shprits, Yuri; Wang, Dedong;

YEAR: 2020     DOI: 10.1029/2019JA027555

Plasmaspheric Hiss; Van Allen Probes; Electron slot region; Statistical modeling; Diffusion simulation; Wave-particle interaction

The Effect of Plasma Boundaries on the Dynamic Evolution of Relativistic Radiation Belt Electrons

Abstract Understanding the dynamic evolution of relativistic electrons in the Earth s radiation belts during both storm and nonstorm times is a challenging task. The U.S. National Science Foundation s Geospace Environment Modeling (GEM) focus group “Quantitative Assessment of Radiation Belt Modeling” has selected two storm time and two nonstorm time events that occurred during the second year of the Van Allen Probes mission for in-depth study. Here, we perform simulations for these GEM challenge events using the 3D Versa ...

Wang, Dedong; Shprits, Yuri; Zhelavskaya, Irina; Effenberger, Frederic; Castillo, Angelica; Drozdov, Alexander; Aseev, Nikita; Cervantes, Sebastian;

YEAR: 2020     DOI: 10.1029/2019JA027422

Radiation belt; simulation; relativistic electrons; magnetopause shadowing; Wave-particle interaction; Plasmapause; 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

Simultaneous Observations of Electromagnetic Ion Cyclotron (EMIC) Waves and Pitch Angle Scattering During a Van Allen Probes Conjunction

On 22 December 2015, the two Van Allen Probes observed two sets of electromagnetic ion cyclotron (EMIC) wave bursts during a close conjunction when both Probe A and Probe B were separated by 0.57 to 0.68 RE. The EMIC waves occurred during an active period in the recovery phase of a coronal mass ejection-driven geomagnetic storm. Both spacecraft observed EMIC wave bursts that had similar spatial structure within a 1–2 min time delay. The EMIC waves occurred outside the plasmasphere, within ΔL ≈ 1–2 of the plasmapau ...

Sigsbee, K.; Kletzing, C. A.; Faden, J.; Jaynes, A. N.; Reeves, G.; Jahn, J.-M.;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027424

EMIC waves; Plasmapause; Proton Anisotropy; Storm Recovery Phase; Van Allen Probes; pitch angle scattering

Raytracing Study of Source Regions of Whistler Mode Wave Power Distribution Relative to the Plasmapause

A comprehensive numerical raytracing study of whistler mode wave power with the inclusion of finite background electron and ion temperature is performed in order to investigate wave power distribution in relation to the plasmapause. Both Landau damping and linear growth of whistler mode waves are taken into account using a bi-Maxwellian hot electron distribution as well as an isotropic hot electron distribution. Isotropic and bi-Maxwellian distributions yield similar results of statistical spatial wave power for frequencies ...

Maxworth, A.; Gołkowski, M.; Malaspina, D.; Jaynes, A.;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027154

hiss; plasmasphere; Warm Plasma; Raytracing; Magnetosphere; Van Allen Probes

Bayesian Inference of Quasi-Linear Radial Diffusion Parameters using Van Allen Probes

The Van Allen radiation belts in the magnetosphere have been extensively studied using models based on radial diffusion theory, which is derived from a quasi-linear approach with prescribed inner and outer boundary conditions. The 1D diffusion model requires the knowledge of a diffusion coefficient and an electron loss timescale, which is typically parameterized in terms of various quantities such as the spatial (L) coordinate or a geomagnetic index (e.g., Kp). These terms are typically empirically derived, not directly meas ...

Sarma, Rakesh; Chandorkar, Mandar; Zhelavskaya, Irina; Shprits, Yuri; Drozdov, Alexander; Camporeale, Enrico;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027618

radial diffusion; Magnetosphere; Bayesian inference; Van Allen radiation belt; Van Allen Probes

The Dynamics of the Inner Boundary of the Outer Radiation Belt During Geomagnetic Storms

We investigate the shapes of the inner boundary of the outer radiation belt during different geomagnetic storm phases using energetic electron observations from Van Allen Probes. The case of two consecutive but isolated storms in April 2016 shows that (a) the inner boundary, as a function of L shell and energy, exhibits a “V-shaped” form with the energetic electrons showing a kappa-like energy spectrum (electron flux steeply falling with increasing energies), whereas it is in a “S-shaped” form as the energetic electr ...

Shi, Xiaofei; Ren, Jie; Zong, Q.;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027309

Van Allen Probes

The Dynamics of the Inner Boundary of the Outer Radiation Belt During Geomagnetic Storms

We investigate the shapes of the inner boundary of the outer radiation belt during different geomagnetic storm phases using energetic electron observations from Van Allen Probes. The case of two consecutive but isolated storms in April 2016 shows that (a) the inner boundary, as a function of L shell and energy, exhibits a “V-shaped” form with the energetic electrons showing a kappa-like energy spectrum (electron flux steeply falling with increasing energies), whereas it is in a “S-shaped” form as the energetic electr ...

Shi, Xiaofei;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027309

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

Whistler Mode Quasiperiodic Emissions: Contrasting Van Allen Probes and DEMETER Occurrence Rates

Quasiperiodic emissions are magnetospheric whistler mode waves at frequencies between about 0.5 and 4 kHz which exhibit a nearly periodic time modulation of the wave intensity. We use large data sets of events observed by the Van Allen Probes in the equatorial region at larger radial distances and by the low-altitude DEMETER spacecraft. While Van Allen Probes observe the events at all local times and longitudes, DEMETER observations are limited nearly exclusively to the daytime and significantly less frequent at the longitud ...

Němec, F.; Santolik, O.; Hospodarsky, G.; Hajoš, M.; Demekhov, A.; Kurth, W.; Parrot, M.; Hartley, D.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA027918

quasiperiodic emissions; QP emissions; DEMETER; RBSP; Van Allen Probes

Quantifying the Effect of Plasmaspheric Hiss on the Electron Loss From the Slot Region

We present global statistical models of both wave amplitude and wave normal angle (WNA) of plasmaspheric hiss using Van Allen Probe-A observations. They utilize the time history of solar wind parameters, that is, interplanetary magnetic field BZ and solar wind speed, and the AE index for each measurement of hiss waves as inputs. The solar wind parameter-based model generally results in higher performance than using only the AE index as an input. Both observations and model results reveal a clear dependence of hiss wave distr ...

Kim, Kyung-Chan; Shprits, Yuri; Wang, Dedong;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027555

Plasmaspheric Hiss; Van Allen Probes; Electron slot region; Statistical modeling; Diffusion simulation; Wave-particle interaction

The Effect of Plasma Boundaries on the Dynamic Evolution of Relativistic Radiation Belt Electrons

Understanding the dynamic evolution of relativistic electrons in the Earth s radiation belts during both storm and nonstorm times is a challenging task. The U.S. National Science Foundation s Geospace Environment Modeling (GEM) focus group “Quantitative Assessment of Radiation Belt Modeling” has selected two storm time and two nonstorm time events that occurred during the second year of the Van Allen Probes mission for in-depth study. Here, we perform simulations for these GEM challenge events using the 3D Versatile Elec ...

Wang, Dedong; Shprits, Yuri; Zhelavskaya, Irina; Effenberger, Frederic; Castillo, Angelica; Drozdov, Alexander; Aseev, Nikita; Cervantes, Sebastian;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027422

Radiation belt; simulation; relativistic electrons; magnetopause shadowing; Wave-particle interaction; Plasmapause; Van Allen Probes



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