Found 1085 entries in the Bibliography.

Showing entries from 201 through 250


Formation of Asymmetric Electron Acoustic Double Layers in the Earth\textquoterights Inner Magnetosphere

The Van Allen Probes have observed both symmetric and asymmetric bipolar electric field structures in the Earth\textquoterights inner magnetosphere. In general, the symmetric bipolar structures are identified as electron-phase space holes, whereas the asymmetric structures are interpreted as electron acoustic double layers (EADLs). The generation mechanism of these EADLs is not entirely understood yet. We have modeled the EADLs observed on 13 November 2012 by Van Allen Probe-B. We performed a fluid simulation of the EADLs an ...

Lotekar, Ajay; Kakad, Amar; Kakad, Bharati;

YEAR: 2019     DOI: 10.1029/2018JA026303

Asymmetric electron acoustic double layers; Electron acoustic shock; Electrostatic solitary wave; Fluid simulation; Van Allen Probes

Substorm-Ring Current Coupling: A Comparison of Isolated and Compound Substorms

Substorms are a highly variable process, which can occur as an isolated event or as part of a sequence of multiple substorms (compound substorms). In this study we identify how the low-energy population of the ring current and subsequent energization varies for isolated substorms compared to the first substorm of a compound event. Using observations of H+ and O+ ions (1 eV to 50 keV) from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the energy content of the ring current in L-MLT space ...

Sandhu, J.; Rae, I.; Freeman, M.; Gkioulidou, M.; Forsyth, C.; Reeves, G.; Murphy, K.; Walach, M.-T.;

YEAR: 2019     DOI: 10.1029/2019JA026766

inner magnetosphere; ring current; substorms; Van Allen; Van Allen Probes

Empirical Modeling of the Geomagnetosphere for SIR and CME-Driven Magnetic Storms

During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow-fast stream interaction regions (SIRs). Previous data-based magnetic field models did not distinguish between these types of the solar wind driving. In the present work we retained the basic structure of the Tsyganenko and Andreeva (2015) model but fitted it to data samples corresponding to (1) SIR-drive ...

Andreeva, V.; Tsyganenko, N.;

YEAR: 2019     DOI: 10.1029/2018JA026008

Magnetic Storms; Magnetosphere; Modeling; Solar wind; spacecraft data; 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;

YEAR: 2019     DOI: 10.1029/2019GL083944

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

Lightning Contribution to Overall Whistler Mode Wave Intensities in the Plasmasphere

Electromagnetic waves generated by lightning propagate into the plasmasphere as dispersed whistlers. They can therefore influence the overall wave intensity in space, which, in turn, is important for dynamics of the Van Allen radiation belts. We analyze spacecraft measurements in low-Earth orbit as well as in high-altitude equatorial region, together with a ground-based estimate of lightning activity. We accumulate wave intensities when the spacecraft are magnetically connected to thunderstorms and compare them with measurem ...

ahlava, J.; emec, F.; Santolik, O.; a, Kolma\v; Hospodarsky, G.; Parrot, M.; Kurth, W.; Kletzing, C.;

YEAR: 2019     DOI: 10.1029/2019GL083918

DEMETER; Lightning; Van Allen Probes; whistler mode; WWLLN

Saturation Characteristics of Parallel EMIC Waves in the Inner Magnetosphere

In this letter, detailed evolution process of parallel electromagnetic ion cyclotron waves in the inner magnetosphere has been investigated through quasilinear theory. A new saturation has been found to occur after the usual first saturation. During the interval between these two saturations, the energy transfers from H+ band to He+ band electromagnetic ion cyclotron waves. Moreover, through a best fitting, we obtain new model parameters for the anisotropy-beta inverse relation of hot H+, which identifies the threshold of io ...

Yu, Xiongdong; Yuan, Zhigang;

YEAR: 2019     DOI: 10.1029/2019GL083630

Anisotropy-beta inverse relation; EMIC waves; Quasilinear theory; RC ions; Van Allen Probes

Statistical Distribution of Whistler Mode Waves in the Radiation Belts With Large Magnetic Field Amplitudes and Comparison to Large Electric Field Amplitudes

We present a statistical analysis with 100\% duty cycle and non-time-averaged amplitudes of the prevalence and distribution of high-amplitude >50-pT whistler mode waves in the outer radiation belt using 5 years of Van Allen Probes data. Whistler mode waves with high magnetic field amplitudes are most common above L=4.5 and between magnetic local time of 0\textendash14 where they are present approximately 1\textendash6\% of the time. During high geomagnetic activity, high-amplitude whistler mode wave occurrence rises above 25 ...

Tyler, E.; Breneman, A.; Cattell, C.; Wygant, J.; Thaller, S.; Malaspina, D.;

YEAR: 2019     DOI: 10.1029/2019JA026913

Magnetosphere; magnetospheric chorus; Radiation belts; Van Allen Probes; whistler wave

Temperature Dependence of Plasmaspheric Ion Composition

We analyze a database of Dynamics Explorer-1 (DE-1) Retarding Ion Mass Spectrometer densities and temperatures to yield the first explicit measure of how cold ion concentration depends on temperature. We find that cold H+ and He+ concentrations have very weak dependence on temperature, but cold O+ ion concentration increases steeply as these ions become warmer. We demonstrate how this result can aid in analyzing composition data from other satellites without spacecraft potential mitigation, by applying the result to an examp ...

Goldstein, J.; Gallagher, D.; Craven, P.; Comfort, R.; Genestreti, K.; Mouikis, C.; Spence, H.; Kurth, W.; Wygant, J.; Skoug, R.; Larsen, B.; Reeves, G.; De Pascuale, S.;

YEAR: 2019     DOI: 10.1029/2019JA026822

composition; plasmasphere: ion; temperature; Van Allen Probes

Variability of the Proton Radiation Belt

Significant steady but slow variability of radiation belt proton intensity, in the energy range \~19\textendash200 MeV and for L<2.4, has been observed in an empirical model derived from data taken by Van Allen Probes during 2013\textendash2019. It is compared to predictions of a theoretical model based on measured initial and boundary conditions. Two aspects of the variability are considered in detail and require adjustments to model parameters. Observed inward transport of proton intensity maxima near L=1.9 and associated ...

Selesnick, R.; Albert, J.;

YEAR: 2019     DOI: 10.1029/2019JA026754

protons; radial diffusion; Radiation belt; Van Allen Probes

Variation of Radiation belt electron flux during CME and CIR driven geomagnetic storms: Van Allen Probes observations

Relativistic electron flux responses in the inner magnetosphere are investigated for 28 magnetic storms driven by Corotating Interaction Region (CIR) and 27 magnetic storms driven by Coronal Mass Ejection (CME), using data from the Relativistic Electron-Proton Telescope (REPT) instrument on board Van-Allen Probes from Oct-2012 to May-2017. In this present study we analyze the role of CIRs and CMEs in electron dynamics by sorting the electron fluxes in terms of averaged solar wind parameters, L-values, and energies. The major ...

Pandya, Megha; Veenadhari, B.; Ebihara, Y.; Kanekal, S.G.; Baker, D.N.;

YEAR: 2019     DOI: 10.1029/2019JA026771

electron flux; innermagnetosphere; Magnetic Storms; Radiation belt; solar wind driver; 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;

YEAR: 2019     DOI: 10.1029/2019JA026556

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

The Evolution of a Pitch-Angle \textquotedblleftBite-Out\textquotedblright Scattering Signature Caused by EMIC Wave Activity: A Case Study

Electromagnetic ion cyclotron (EMIC) waves are understood to be one of the dominant drivers of relativistic electron loss from Earth\textquoterights radiation belts. Theory predicts that the associated gyroresonant wave-particle interaction results in a distinct energy-dependent \textquotedblleftbite-out\textquotedblright signature in the normalized flux distribution of electrons as they are scattered into the loss cone. We identify such signatures along with the responsible EMIC waves captured in situ by the Van Allen Probe ...

Bingley, L.; Angelopoulos, V.; Sibeck, D.; Zhang, X.; Halford, A.;

YEAR: 2019     DOI: 10.1029/2018JA026292

Van Allen Probes

Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth\textquoterights Inner Magnetosphere

Electromagnetic ion cyclotron (EMIC) waves and magnetosonic waves are commonly observed in the Earth\textquoterights magnetosphere associated with enhanced ring current activity. Using wave and ion measurements from the Van Allen Probes, we identify clear correlations between the hydrogen- and helium-band EMIC waves with the enhancement of trapped helium and oxygen ion fluxes, respectively. We calculate the diffusion coefficients of different ion species using quasi-linear theory to understand the effects of resonant scatter ...

Ma, Q.; Li, W.; Yue, C.; Thorne, R.; Bortnik, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Reeves, G.; Spence, H.;

YEAR: 2019     DOI: 10.1029/2019GL083513

electromagnetic ion cyclotron waves; Ion heating; Quasilinear modeling; Resonant interaction in plasmasphere; ring current; Van Allen Probes; Van Allen Probes observation

The Magnetospheric Driving Source of Double-Peak Subauroral Ion Drifts: Double Ring Current Pressure Peaks

Double-peak subauroral ion drifts (DSAIDs), characterized by two high-speed flow channels, is a newly identified flow structure in the subauroral ionosphere. He et al. (2016, proposed that two region 2 field-aligned currents (R2 FACs) might cause the DSAIDs. However, the underlying physical process that drives the double R2 FACs is unknown. This study reports a DSAIDs event and reveals its magnetospheric drivers. Defense Meteorological Satellite Program F18 satellite observed DSAIDs in t ...

Wei, Dong; Yu, Yiqun; He, Fei;

YEAR: 2019     DOI: 10.1029/2019GL083186

Van Allen Probes

Nonlinear Electron Interaction With Intense Chorus Waves: Statistics of Occurrence Rates

A comprehensive statistical analysis on 8 years of lower-band chorus wave packets measured by the Van Allen Probes and THEMIS spacecraft is performed to examine whether, when, and where these waves are above the theoretical threshold for nonlinear resonant wave-particle interaction. We find that \~5\textendash30\% of all chorus waves interact nonlinearly with \~30- to 300-keV electrons possessing equatorial pitch angles of >40\textdegree in the outer radiation belt, especially during disturbed (AE>500 nT) periods with energe ...

Zhang, X.-J.; Mourenas, D.; Artemyev, A.; Angelopoulos, V.; Bortnik, J.; Thorne, R.; Kurth, W.; Kletzing, C.; Hospodarsky, G.;

YEAR: 2019     DOI: 10.1029/2019GL083833

chorus waves; Electron acceleration; nonlinear wave particle interaction; THEMIS; Van Allen Probes; wave packet size

Simulation of Prompt Acceleration of Radiation Belt Electrons During the 16 July 2017 Storm

We investigate the prompt enhancement of radiation belt electron flux observed by the Relativistic Electron Proton Telescope instrument on board Van Allen Probes following the 16 July 2017 CME-shock compression using MHD-test particle simulations. The prompt enhancements can be explained by the source population interacting with the azimuthally directed electric field impulses induced by CME-shock compressions of the dayside magnetopause. Electrons in drift resonance with the electric field impulse were accelerated by \~ 0.6 ...

Patel, Maulik; Li, Zhao; Hudson, Mary; Claudepierre, Seth; Wygant, John;

YEAR: 2019     DOI: 10.1029/2019GL083257

Van Allen Probes

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

Characteristics of high energy proton responses to geomagnetic activities in the inner radiation belt observed by the RBSP satellite

High energy trapped particles in the radiation belts constitute potential threats to the functionality of satellites as they enter into those regions. In the inner radiation belt, the characteristics of high-energy (>20MeV) protons variations during geomagnetic activity times have been studied by implementing four-year (2013-2016) observations of the Van Allen probes. An empirical formula has been used to remove the satellite orbit effect, by which proton fluxes have been normalized to the geomagnetic equator. Case studies s ...

Xu, Jiyao; He, Zhaohai; Baker, D.N.; Roth, Ilan; Wang, C.; Kanekal, S.G.; Jaynes, A.N.; Liu, Xiao;

YEAR: 2019     DOI: 10.1029/2018JA026205

geomagnetic activities; high energy proton; Inner radiation belt; one-to-one correspondence; prompt responses; RBSP satellite; 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.;

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

Conjugate Ionosphere-Magnetosphere Observations of a Sub-Alfv\ enic Compressional Intermediate- m Wave: A Case Study Using EKB Radar and Van Allen Probes

A Pc5 wave was simultaneously observed in the ionosphere by EKB radar and in the magnetosphere by both Van Allen Probe spacecraft within a substorm activity. The wave was located in the nightside, in 1.5- to 3-hr magnetic local time sector, and in the region corresponding to the magnetic shells with maximal distances 4.6\textendash7.8 Earth\textquoterights radii. As it was found using both the radar and spacecraft data, the wave had frequency of about 1.8 mHz and azimuthal wave number m≈-10; that is, the wave was westward ...

Mager, Olga; Chelpanov, Maksim; Mager, Pavel; Klimushkin, Dmitri; Berngardt, Oleg;

YEAR: 2019     DOI: 10.1029/2019JA026541

compressional waves; Pc5; poloidal waves; SUPERDARN; ULF waves; 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

Effect of Low-Harmonic Magnetosonic Waves on the Radiation Belt Electrons Inside the Plasmasphere

In this paper, we presented two observational cases and simulations to indicate the relationship between the formation of butterfly-like electron pitch angle distributions and the emission of low-harmonic (LH) fast magnetosonic (MS) waves inside the high-density plasmasphere. In the wave emission region, the pitch angle of relativistic (>1 MeV) electrons becomes obvious butterfly-like distributions for both events (near-equatorially mirroring electrons are transported to lower pitch angles). Unlike relativistic (>1 MeV) elec ...

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

YEAR: 2019     DOI: 10.1029/2018JA026328

bounce resonance; Electron acceleration; Landau resonance; magnetosonic waves; transit-time scattering; Van Allen Probes

Epoch-Based Model for Stormtime Plasmapause Location

The output of a plasmapause test particle (PTP) code is used to formulate a new epoch-based plasmapause model. The PTP simulation is run for an ensemble of 60 storms spanning 3 September 2012 to 28 September 2017 and having peak Dst of -60 nT or less, yielding over 7 million model plasmapause locations. Events are automatically identified and epoch times calculated relative to the respective storm peaks. Epoch analysis of the simulated plasmapause is demonstrated to be an effective method to reveal the dynamical phases of pl ...

Goldstein, J.; De Pascuale, S.; Kurth, W.;

YEAR: 2019     DOI: 10.1029/2018JA025996

epoch-based model; Plasmapause; plasmasphere; plume; Van Allen Probes

Evaluation of Plasma Properties From Chorus Waves Observed at the Generation Region

In this study we present an inversion method which provides thermal plasma population parameters from characteristics of chorus emissions only. Our ultimate goal is to apply this method to ground-based data in order to derive the lower-energy boundary condition for many radiation belt models. The first step is to test the chorus inversion method on in situ data of the Van Allen Probes in the generation region. The density and thermal velocity of energetic electrons (few kiloelectron volts to 100 keV) are derived from frequen ...

asz, Lilla; Omura, Yoshiharu; Lichtenberger, J\; Friedel, Reinhard;

YEAR: 2019     DOI: 10.1029/2018JA026337

chorus inversion; Van Allen Probes; Wave-particle interaction

Generation of EMIC Waves and Effects on Particle Precipitation During a Solar Wind Pressure Intensification with B z >

During geomagnetic storms, some fraction of the solar wind energy is coupled via reconnection at the dayside magnetopause, a process that requires a southward interplanetary magnetic field Bz. Through a complex sequence of events, some of this energy ultimately drives the generation of electromagnetic ion cyclotron (EMIC) waves, which can then scatter energetic electrons and ions from the radiation belts. In the event described in this paper, the interplanetary magnetic field remained northward throughout the event, a condit ...

Lessard, Marc; Paulson, Kristoff; Spence, Harlan; Weaver, Carol; Engebretson, Mark; Millan, Robyn; Woodger, Leslie; Halford, Alexa; Horne, Richard; Rodger, Craig; Hendry, Aaron;

YEAR: 2019     DOI: 10.1029/2019JA026477

Van Allen Probes

Investigating Loss of Relativistic Electrons Associated With EMIC Waves at Low L Values on 22 June 2015

In this study, rapid loss of relativistic radiation belt electrons at low L* values (2.4\textendash3.2) during a strong geomagnetic storm on 22 June 2015 is investigated along with five possible loss mechanisms. Both the particle and wave data are obtained from the Van Allen Probes. Duskside H+ band electromagnetic ion cyclotron (EMIC) waves were observed during a rapid decrease of relativistic electrons with energy above 5.2 MeV occurring outside the plasmasphere during extreme magnetopause compression. Lower He+ compositio ...

Qin, Murong; Hudson, Mary; Li, Zhao; Millan, Robyn; Shen, Xiaochen; Shprits, Yuri; Woodger, Leslie; Jaynes, Allison; Kletzing, Craig;

YEAR: 2019     DOI: 10.1029/2018JA025726

cold ion composition; EMIC wave; minimum resonant energy; pitch angle diffusion; quasi-linear theory; relativistic electron loss; Van Allen Probes

Multiple satellites observation evidence: High-m Poloidal ULF waves with time-varying polarization states

We report multi-spacecraft observations of ULF waves from Van Allen Probes (RBSP), Magnetospheric Multiscale (MMS), Time History of Events and Macroscale Interactions during Substorm (THEMIS), and Geostationary Operational Environmental Satellites (GOES). On August 31, 2015, global-scale poloidal waves were observed in data from RBSP-B, GOES and THEMIS from L=4 to L=8 over a wide range of magnetic local time (MLT). The polarization states varied towards purely poloidal polarity. In two consecutive orbits over 18 hours, RBSP- ...

Wei, Chao; Dai, Lei; Duan, Suping; Wang, Chi; Wang, YuXian;

YEAR: 2019     DOI: 10.26464/epp2019021

bump-on-tail; inward gradient; polarization rotation; poloidal waves; Van Allen Probes

Quenching of Equatorial Magnetosonic Waves by Substorm Proton Injections

Near equatorial (fast) magnetosonic waves, characterized by high magnetic compressibility, are whistler-mode emissions destabilized by proton shell/ring distributions. In the past, substorm proton injections are widely known to intensify magnetosonic waves in the inner magnetosphere. Here we report the unexpected observations by the Van Allen Probes of the magnetosonic wave quenching associated with the substorm proton injections under both high- and low-density conditions. The enhanced proton thermal pressure distorted the ...

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

YEAR: 2019     DOI: 10.1029/2019GL082944

Bernstein mode instability; magnetosonic wave; Radiation belt; ring current; substorm injection; Van Allen Probes; Wave-particle interaction

Statistical Analysis of Transverse Size of Lower Band Chorus Waves Using Simultaneous Multisatellite Observations

Chorus waves are known to accelerate or scatter energetic electrons via quasi-linear or nonlinear wave-particle interactions in the Earth\textquoterights magnetosphere. In this letter, by taking advantage of simultaneous observations of chorus waveforms from at least a pair of probes among Van Allen Probes and/or Time History of Events and Macroscale Interactions during Substorms (THEMIS) missions, we statistically calculate the transverse size of lower band chorus wave elements. The average size of lower band chorus wave el ...

Shen, Xiao-Chen; Li, Wen; Ma, Qianli; Agapitov, Oleksiy; Nishimura, Yukitoshi;

YEAR: 2019     DOI: 10.1029/2019GL083118

Chorus wave; Magnetosphere; Scale size; Van Allen Probes

Statistical Properties of Hiss in Plasmaspheric Plumes and Associated Scattering Losses of Radiation Belt Electrons

Whistler mode hiss acts as an important loss mechanism contributing to the radiation belt electron dynamics inside the plasmasphere and plasmaspheric plumes. Based on Van Allen Probes observations from September 2012 to December 2015, we conduct a detailed analysis of hiss properties in plasmaspheric plumes and illustrate that corresponding to the highest occurrence probability of plumes at L = 5.0\textendash6.0 and MLT = 18\textendash21, hiss emissions occur concurrently with a rate of >~80\%. Plume hiss can efficiently sca ...

Zhang, Wenxun; Ni, Binbin; Huang, He; Summers, Danny; Fu, Song; Xiang, Zheng; Gu, Xudong; Cao, Xing; Lou, Yuequn; Hua, Man;

YEAR: 2019     DOI: 10.1029/2018GL081863

Electron scattering; plasmaspheric plumes; plume hiss; Van Allen Probes

Timescales for electron quasi-linear diffusion by lower-band chorus waves: the effects of ω pe / Ω ce dependence on geomagnetic activity

Electron scattering by chorus waves is an important mechanism that can lead to fast electron acceleration and loss in the outer radiation belt. Making use of Van Allen Probes measurements, we present the first statistical survey of megaelectron volt electron pitch angle and energy quasi-linear diffusion rates by chorus waves as a function of L-shell, local time, and AE index, taking into account the local electron plasma frequency to gyrofrequency ratio ωpe/Ωce, chorus wave frequency, and resonance wave amplitude. We demon ...

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

YEAR: 2019     DOI: 10.1029/2019GL083446

magnetosphere plasma density; quasi-linear scattering and acceleration; Van Allen Probes; wave-particle interactions

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

Cyclotron Acceleration of Relativistic Electrons Through Landau Resonance With Obliquely Propagating Whistler-Mode Chorus Emissions

Efficient acceleration of relativistic electrons at Landau resonance with obliquely propagating whistler-mode chorus emissions is confirmed by theory, simulation, and observation. The acceleration is due to the perpendicular component of the wave electric field. We first review theoretical analysis of nonlinear motion of resonant electrons interacting with obliquely propagating whistler-mode chorus. We have derived formulae of inhomogeneity factors for Landau and cyclotron resonances to analyze nonlinear wave trapping of ene ...

Omura, Yoshiharu; Hsieh, Yi-Kai; Foster, John; Erickson, Philip; Kletzing, Craig; Baker, Daniel;

YEAR: 2019     DOI: 10.1029/2018JA026374

inner magnetosphere; nonlinear process; Radiation belts; relativistic electrons; Van Allen Probes; wave particle interaction; whistler-mode chorus

EMIC waves converted from equatorial noise due to M/Q=2 ions in the plasmasphere: Observations from Van Allen Probes and Arase

Equatorial noise (EN) emissions are observed inside and outside the plasmapause. EN emissions are referred to as magnetosonic mode waves. Using data from Van Allen Probes and Arase, we found conversion from EN emissions to electromagnetic ion cyclotron (EMIC) waves in the plasmasphere and in the topside ionosphere. A low frequency part of EN emissions becomes EMIC waves through branch splitting of EN emissions, and the mode conversion from EN to EMIC waves occurs around the frequency of M/Q=2 (deuteron and/or alpha particles ...

Miyoshi, Y.; Matsuda, S.; Kurita, S.; Nomura, K.; Keika, K.; Shoji, M.; Kitamura, N.; Kasahara, Y.; Matsuoka, A.; Shinohara, I.; Shiokawa, K.; Machida, S.; Santolik, O.; Boardsen, S.A.; Horne, R.B.; Wygant, J.F.;

YEAR: 2019     DOI: 10.1029/2019GL083024

Arase; EMIC; M/Q=2 ions; Magnetsonic waves; plasmasphere; 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

Investigation of Solar Proton Access into the inner magnetosphere on 11 September 2017

In this study, access of solar energetic protons to the inner magnetosphere on 11 September 2017 is investigated by computing the reverse particle trajectories with the Dartmouth geomagnetic cutoff code [Kress et al., 2010]. The maximum and minimum cutoff rigidity at each point along the orbit of Van Allen Probe A is numerically computed by extending the code to calculate cutoff rigidity for particles coming from arbitrary direction. Pulse-height analyzed (PHA) data has the advantage of providing individual particle energies ...

Qin, Murong; Hudson, Mary; Kress, Brian; Selesnick, Richard; Engel, Miles; Li, Zhao; Shen, Xiaochen;

YEAR: 2019     DOI: 10.1029/2018JA026380

cutoff energy; cutoff location; Dartmouth geomagnetic cutoff code; Pulse height analyzed data; Solar proton; straggling function; Van Allen Probes

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

Quasi Thermal Noise Spectroscopy for Van Allen Probes

Quasi thermal fluctuations in the Langmuir/upper-hybrid frequency range are pervasively observed in space plasmas including the radiation belt and the ring current region of inner magnetosphere as well as the solar wind. The quasi thermal noise spectroscopy may be employed in order to determine the electron density and temperature as well as to diagnose the properties of energetic electrons when direct measurements are not available. However, when employing the technique, one must carefully take the spacecraft orientation in ...

Yoon, Peter; Hwang, Junga; Kim, Hyangpyo; Seough, Jungjoon;

YEAR: 2019     DOI: 10.1029/2019JA026460

(n+1/2)fce; antenna geometry; Quasi-thermal; Radiation belt; Upper hybrid; Van Allen Probes

Reanalysis of Ring Current Electron Phase Space Densities Using Van Allen Probe Observations, Convection Model, and Log-Normal Kalman Filter

Aseev, N.; . Y. Shprits, Y;

YEAR: 2019     DOI: 10.1029/2018SW002110

data assimilation; inner magnetosphere; Kalman Filter; Reanalysis; ring current; Van Allen Probes

Reanalysis of ring current electron phase space densities using Van Allen Probe observations, convection model, and log-normal Kalman filter

Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics-based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log-transformed convec ...

Aseev, N.A.; Shprits, Y.Y.;

YEAR: 2019     DOI: 10.1029/2018SW002110

data assimilation; inner magnetosphere; Kalman Filter; Reanalysis; ring current; Van Allen Probes

The Relationship Between EMIC Wave Properties and Proton Distributions Based on Van Allen Probes Observations

Plasma kinetic theory predicts that sufficiently anisotropic proton distribution will excite electromagnetic ion cyclotron (EMIC) waves, which in turn relax the proton distribution to a marginally stable state creating an upper bound on the relaxed proton anisotropy. Here, using EMIC wave observations and coincident plasma measurements made by Van Allen Probes in the inner magnetosphere, we show that the proton distributions are well constrained by this instability to a marginally stable state. Near the threshold, the probab ...

Yue, Chao; Jun, Chae-Woo; Bortnik, Jacob; An, Xin; Ma, Qianli; Reeves, Geoffrey; Spence, Harlan; Gerrard, Andrew; Gkioulidou, Matina; Mitchell, Donald; Kletzing, Craig;

YEAR: 2019     DOI: 10.1029/2019GL082633

EMIC waves; helium-band; hydrogen-band; plasma beta; proton temperature anisotropy; Van Allen Probes

Shorting Factor In-Flight Calibration for the Van Allen Probes DC Electric Field Measurements in the Earth\textquoterights Plasmasphere

Satellite-based direct electric field measurements deliver crucial information for space science studies. Yet they require meticulous design and calibration. In-flight calibration of double-probe instruments is usually presented in the most common case of tenuous plasmas, where the presence of an electrostatic structure surrounding the charged spacecraft alters the geophysical electric field measurements. To account for this effect and the uncertainty in the boom length, the measured electric field is multiplied by a paramet ...

Lejosne, Solène; Mozer, F.;

YEAR: 2019     DOI: 10.1029/2018EA000550

DC electric field; double probe instrument; electric drift; plasmasphere; shorting factor; Van Allen Probes

Space Research and Space Weather: Some Personal Vignettes 1965 to Early 1980s

Personal vignettes are given on early days of space research, space weather, and space advisory activities from 1965 to early 1980s.

Lanzerotti, Louis;

YEAR: 2019     DOI: 10.1029/2019JA026763

Van Allen Probes

Statistical Study of Selective Oxygen Increase in High-Energy Ring Current Ions During Magnetic Storms

Ion transport from the plasma sheet to the ring current is the main cause of the development of the ring current. Energetic (>150 keV) ring current ions are known to be transported diffusively in several days. A recent study suggested that energetic oxygen ions are transported closer to the Earth than protons due to the diffusive transport caused by a combination of the drift and drift-bounce resonances with Pc 3\textendash5 ultralow frequency waves during the 24 April 2013 magnetic storm. To understand the occurrence condit ...

Mitani, K.; Seki, K.; Keika, K.; Gkioulidou, M.; Lanzerotti, L.; Mitchell, D.; Kletzing, C.; Yoshikawa, A.; Obana, Y.;

YEAR: 2019     DOI: 10.1029/2018JA026168

Magnetic Storms; Oxygen ions; ring current; 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.;

YEAR: 2019     DOI: 10.1029/2018JA026257

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

EMIC Wave-Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere

While electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron-resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower-energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth\textquoterig ...

Blum, L.W.; Artemyev, A.; Agapitov, O.; Mourenas, D.; Boardsen, S.; Schiller, Q.;

YEAR: 2019     DOI: 10.1029/2018JA026427

bounce resonance; EMIC wave; energetic electrons; Radiation belts; Van Allen Probes

Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity

Electromagnetic ion cyclotron (EMIC) waves can drive precipitation of tens of keV protons and relativistic electrons, and are a potential candidate for causing radiation belt flux dropouts. In this study, we quantitatively analyze three cases of EMIC-driven precipitation, which occurred near the dusk sector observed by multiple Low-Earth-Orbiting (LEO) Polar Operational Environmental Satellites/Meteorological Operational satellite programme (POES/MetOp) satellites. During EMIC wave activity, the proton precipitation occurred ...

Capannolo, L.; Li, W.; Ma, Q.; Shen, X.-C.; Zhang, X.-J.; Redmon, R.; Rodriguez, J.; Engebretson, M.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Raita, T.;

YEAR: 2019     DOI: 10.1029/2018JA026291

EMIC waves; energetic electron precipitation; pitch angle scattering; quasi-linear theory; radiation belts dropouts; Van Allen Probes

Local and Statistical Maps of Lightning-Generated Wave Power Density Estimated at the Van Allen Probes Footprints From the World-Wide Lightning Location Network Database

We propose a new method that uses the World-Wide Lightning Location Network (WWLLN) to estimate both the local and the drift lightning power density at the Van Allen Probes footprints during 4.3 years (~2 \texttimes 108 strokes.). The ratio of the drift power density to the local power density defines a time-resolved WWLLN-based model of lightning-generated wave (LGW) power density ratio, RWWLLN. RWWLLNis computed every ~34 s. This ratio multiplied by the time-resolved LGW intensity measured by the Probes allows direct compu ...

Ripoll, J.-F.; Farges, T.; Lay, E.; Cunningham, G.;

YEAR: 2019     DOI: 10.1029/2018GL081146

drift wave power density; lightning power density; lightning-generated waves; occurrence rate; Radiation belts; Van Allen Probes; WWLLN database

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;

YEAR: 2019     DOI: 10.1029/2018JA026259

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

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