Found 1014 entries in the Bibliography.

Showing entries from 551 through 600


The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data

Energetic electron observations in Earth\textquoterights radiation belts are typically sparse and multi-point studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross-calibration into two parts \textendash one that removes any spectral assumptions fr ...

Morley, Steven; Sullivan, John; Henderson, Michael; Blake, Bernard; Baker, Daniel;

YEAR: 2016     DOI: 10.1002/2015SW001339

Global Positioning System; Van Allen Probes

Intense low-frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons

Frequency distribution is a vital factor in determining the contribution of whistler-mode chorus to radiation belt electron dynamics. Chorus is usually considered to occur in the frequency range 0.1\textendash0.8 inline image (with the equatorial electron gyrofrequency inline image). We here report an event of intense low-frequency chorus with nearly half of wave power distributed below 0.1 inline image observed by Van Allen Probe A on 27 August 2014. This emission propagated quasi-parallel to the magnetic field and exhibi ...

Gao, Zhonglei; Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zheng, Huinan; Wang, Yuming; Shen, Chao; Wang, Shui;

YEAR: 2016     DOI: 10.1002/2016GL067687

Cyclotron resonance; Hiss-like band; Low-frequency chorus; Radiation belt; Van Allen Probes; Rising tones; Van Allen Probes

New global loss model of energetic and relativistic electrons based on Van Allen Probes measurements

Energetic electron observations in Earth\textquoterights radiation belts are typically sparse and multi-point studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross-calibration into two parts \textendash one that removes any spectral assumptions fr ...

Orlova, Ksenia; Shprits, Yuri; Spasojevic, Maria;

YEAR: 2016     DOI: 10.1002/2015JA021878

Global Positioning System; Van Allen Probes

Pulsating proton aurora caused by rising tone Pc1 waves

We found rising tone emissions with a dispersion of \~1 Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over \~30 min from 0250 UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7\textdegreeN, 246.7\textdegreeE, magnetic latitude 61.7\textdegreeN). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsa ...

Nomura, R.; Shiokawa, K.; Omura, Y.; Ebihara, Y.; Miyoshi, Y.; Sakaguchi, K.; Otsuka, Y.; Connors, M.;

YEAR: 2016     DOI: 10.1002/2015JA021681

EMIC-triggered waves; Pc1 waves; proton aurora

Reconstructing the magnetosphere from data using radial basis functions

A new method is proposed to derive from data magnetospheric magnetic field configurations without any a priori assumptions on the geometry of electric currents. The approach utilizes large sets of archived satellite data and uses an advanced technique to represent the field as a sum of toroidal and poloidal parts, whose generating potentials Ψ1 and Ψ2 are expanded into series of radial basis functions (RBF) with their nodes regularly distributed over the 3D modeling domain. The method was tested by reconstructing the inner ...

Andreeva, Varvara; Tsyganenko, Nikolai;

YEAR: 2016     DOI: 10.1002/2015JA022242

current systems; magnetospheric modeling; polar cusps; Van Allen Probes

Relativistic electron microbursts and variations in trapped MeV electron fluxes during the 8-9 October 2012 storm: SAMPEX and Van Allen Probes observations

It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Relativistic electron microbursts have been considered as an important loss mechanism of radiation belt electrons. Here we report on the observations of relativistic electron microbursts and flux variations of trapped MeV electrons during the 8\textendash9 October 2012 storm, using the SAMPEX and Van Allen Probes satellites. Observations by th ...

Kurita, Satoshi; Miyoshi, Yoshizumi; Blake, Bernard; Reeves, Geoffery; Kletzing, Craig;

YEAR: 2016     DOI: 10.1002/2016GL068260

Radiation belts; relativistic electron microbursts; relativistic electrons; SAMPEX; Van Allen Probes; whistler mode chorus

Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to ele ...

Sarno-Smith, Lois; Larsen, Brian; Skoug, Ruth; Liemohn, Michael; Breneman, Aaron; Wygant, John; Thomsen, Michelle;

YEAR: 2016     DOI: 10.1002/2015SW001345

EFW; HOPE; spacecraft charging; surface charging; Van Allen Probes

Survey of the Frequency Dependent Latitudinal Distribution of the Fast Magnetosonic Wave Mode from Van Allen Probes EMFISIS Wave Form Receiver Plasma Wave Analysis

We present a statistical survey of the latitudinal structure of the fast magnetosonic wave mode detected by the Van Allen Probes spanning the time interval of 9/21/2012 to 8/1/2014. We show that statistically the latitudinal occurrence of the wave frequency (f) normalized by the local proton cyclotron frequency (fcP) has a distinct funnel shaped appearance in latitude about the magnetic equator similar to that found in case studies. By comparing the observed E/B ratios with the model E/B ratio, using the observed plasma dens ...

Boardsen, Scott; Hospodarsky, George; Kletzing, Craig; Engebretson, Mark; Pfaff, Robert; Wygant, John; Kurth, William; Averkamp, Terrance; Bounds, Scott; Green, Jim; De Pascuale, Sebastian;

YEAR: 2016     DOI: 10.1002/2015JA021844

EMFISIS; Fast Magnetosonic Waves; latitudinal distribution; statistical study; Van Allen Probes; wave normal angle

On the Connection Between Microbursts and Nonlinear Electronic Structures in Planetary Radiation Belts

Using a dynamical-system approach, we have investigated the efficiency of large-amplitude whistler waves for causing microburst precipitation in planetary radiation belts by modeling the microburst energy and particle fluxes produced as a result of nonlinear wave\textendashparticle interactions. We show that wave parameters, consistent with large-amplitude oblique whistlers, can commonly generate microbursts of electrons with hundreds of keV-energies as a result of Landau trapping. Relativistic microbursts (>1 MeV) can also ...

Osmane, Adnane; III, Lynn; Blum, Lauren; Pulkkinen, Tuija;

YEAR: 2016     DOI: 10.3847/0004-637X/816/2/51

acceleration of particles; Earth; Plasmas; relativistic processes; solar\textendashterrestrial relations; Van Allen Probes; waves

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021863

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

Dipolarizing flux bundles in the cis-geosynchronous magnetosphere: relationship between electric fields and energetic particle injections

Dipolarizing flux bundles (DFBs) are small flux tubes (typically < 3 RE in XGSM and YGSM) in the nightside magnetosphere that have magnetic field more dipolar than the background. Although DFBs are known to accelerate particles, creating energetic particle injections outside geosynchronous orbit (trans-GEO), the nature of the acceleration mechanism and the importance of DFBs in generating injections inside geosynchronous orbit (cis-GEO) are unclear. Our statistical study of cis-GEO DFBs using data from the Van Allen Probes r ...

Liu, Jiang; Angelopoulos, V.; Zhang, Xiao-Jia; Turner, D.; Gabrielse, C.; Runov, A.; Li, Jinxing; Funsten, H.; Spence, H.;

YEAR: 2016     DOI: 10.1002/2015JA021691

dipolarization front; dipolarizing flux bundle; energetic particle injection; geosynchronous orbit; magnetic storm; Particle acceleration

The effects of the big storm events in the first half of 2015 on the radiation belts observed by EPT/PROBA-V

With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of hi ...

Pierrard, V.; Rosson, G.;

YEAR: 2016     DOI: 10.5194/angeo-34-75-2016

Van Allen Probes

Near-Relativistic Electron Acceleration by Landau Trapping in Time Domain Structures

Data from the Van Allen Probes have provided the first extensive evidence of nonlinear (as opposed to quasi-linear) wave-particle interactions in space with the associated rapid (less than a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric field of time domain structures (TDSs) traveling at high speeds (~20,000 km/s). This observational evidence is supported by simulations and discussion of the source and spatial extent of the fast TDS. This result indicates the possibility ...

Mozer, F.; Artemyev, A.; Agapitov, O.; Mourenas, D.; Vasko, I.;

YEAR: 2016     DOI: 10.1002/2015GL067316

Acceleration; Van Allen Probes

Nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012

In this study, we investigate the possibility of nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012. The data we use were measured by the Van Allen Probe B. Wave data and plasma sheet electron data are analyzed. Chorus waves were frequently measured in the morning side during the main phase of this storm. Large-amplitude chorus waves were seen of the order of \~0.6 nT and >7 mV/m, which are similar to or larger than the typical ULF waves. The waves quite often consist of rising tones during the burst ...

Matsui, H.; Paulson, K.; Torbert, R.; Spence, H.; Kletzing, C.; Kurth, W.; Skoug, R.; Larsen, B.; Breneman, A.;

YEAR: 2016     DOI: 10.1002/2015JA021772

chorus waves; Geomagnetic storm; nonlinearity; Van Allen Probes

Van Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC waves, ULF pulsations, and an electron flux dropout

We examined an electron flux dropout during the 12\textendash14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, THEMIS-A (P5), Cluster 2, and Geostationary Operational Environmental Satellite (GOES) 13, 14, and 15. The electron fluxes for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 hours from 12\textendash14 November. For energies of 0.8 ...

Sigsbee, K.; Kletzing, C.; Smith, C.; MacDowall, Robert; Spence, Harlan; Reeves, Geoff; Blake, J.; Baker, D.; Green, J.; Singer, H.; Carr, C.; ik, O.;

YEAR: 2016     DOI: 10.1002/2014JA020877

Dst Effect; Electron Flux Dropouts; EMIC waves; magnetopause shadowing; ULF Pulsations; Van Allen Probes

Variation in crossover frequency of EMIC waves in plasmasphere estimated from ion cyclotron whistler waves observed by Van Allen Probe A

We report variations in the propagation of the H+ band ion cyclotron whistlers observed by Van Allen Probe A. Ion cyclotron whistlers are one of the EMIC (electromagnetic ion cyclotron) waves generated by mode conversion from lightning whistlers. Crossover frequency is an important frequency for the ion cyclotron whistlers, which is a function of the variations in the local heavy-ion composition. We surveyed waveform data obtained by the Electric and Magnetic Field Instrument and Integrated Science instrument and found that ...

Matsuda, Shoya; Kasahara, Yoshiya; Kletzing, Craig;

YEAR: 2016     DOI: 10.1002/2015GL066893

EMIC wave; ion cyclotron whistler; plasmasphere; heavy ions; Van Allen Probes

The \textquotedblleftzebra stripes\textquotedblright: An effect of F-region zonal plasma drifts on the longitudinal distribution of radiation belt particles

We examine a characteristic effect, namely, the ubiquitous appearance of structured peaks and valleys called zebra stripes in the spectrograms of energetic electrons and ions trapped in the inner belt below L ~ 3. We propose an explanation of this phenomenon as a purely kinematic consequence of particle drift velocity modulation caused by F region zonal plasma drifts in the ionosphere. In other words, we amend the traditional assumption that the electric field associated with ionospheric plasma drives trapped particle distri ...

Lejosne, Solène; Roederer, Juan;

YEAR: 2016     DOI: 10.1002/2015JA021925

electric field; Ionosphere; Inner radiation belt; Van Allen Probes; zebra stripes


Extreme ionospheric ion energization and electron heating in Alfv\ en waves in the storm-time inner magnetosphere

We report measurements of energized outflowing/bouncing ionospheric ions and heated electrons in the inner magnetosphere during a geomagnetic storm. The ions arrive in the equatorial plane with pitch angles that increase with energy over a range from tens of eV to > 50 keV while the electrons are field-aligned up to ~1 keV. These particle distributions are observed during intervals of broadband low frequency electromagnetic field fluctuations consistent with a Doppler-shifted spectrum of kinetic Alfv\ en waves and kinetic fi ...

Chaston, C.; Bonnell, J.; Wygant, J.; Kletzing, C.; Reeves, G.; Gerrard, A.; Lanzerotti, L.; Smith, C.;

YEAR: 2015     DOI: 10.1002/2015GL066674

Alfven waves; electron precipitation; Geomagnetic storms; ion acceleration; ion outflow; ion upflo

Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 \texttimes 10-6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59\textdegree), where the scattered wavelength reaches the limits of the plasma column. The scatt ...

Tejero, E.; Crabtree, C.; Blackwell, D.; Amatucci, W.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.;

YEAR: 2015     DOI: 10.1038/srep17852

Magnetically confined plasmas; Magnetospheric physics

Nonlinear local parallel acceleration of electrons through Landau trapping by oblique whistler mode waves in the outer radiation belt

Simultaneous observations of electron velocity distributions and chorus waves by the Van Allen Probe B are analyzed to identify long-lasting (more than 6 h) signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. Such Landau resonant interactions result in the trapping of \~1\textendash10 keV electrons and their acceleration up to 100\textendash300 keV. This kind of process becomes important for oblique whistler mode waves having a significant electric field component along ...

Agapitov, O.; Artemyev, A.; Mourenas, D.; Mozer, F.; Krasnoselskikh, V.;

YEAR: 2015     DOI: 10.1002/2015GL066887

Landau resonance; nonlinear acceleration of electrons; oblique whistlers; Radiation belts; seed population; Van Allen Probes

Observations of discrete magnetosonic waves off the magnetic equator

Fast mode magnetosonic waves are typically confined close to the magnetic equator and exhibit harmonic structures at multiples of the local, equatorial proton cyclotron frequency. We report observations of magnetosonic waves well off the equator at geomagnetic latitudes from -16.5\textdegreeto -17.9\textdegree and L shell ~2.7\textendash4.6. The observed waves exhibit discrete spectral structures with multiple frequency spacings. The predominant frequency spacings are ~6 and 9 Hz, neither of which is equal to the local proto ...

Zhima, Zeren; Chen, Lunjin; Fu, Huishan; Cao, Jinbin; Horne, Richard; Reeves, Geoff;

YEAR: 2015     DOI: 10.1002/2015GL066255

discrete structure; magnetsonic wave; off-equatorial region

Survey of radiation belt energetic electron pitch angle distributions based on the Van Allen Probes MagEIS measurements

A statistical survey of electron pitch angle distributions (PADs) is performed based on the pitch angle resolved flux observations from the Magnetic Electron Ion Spectrometer (MagEIS) instrument on board the Van Allen Probes during the period from 1 October 2012 to 1 May 2015. By fitting the measured PADs to a sinnα form, where α is the local pitch angle and n is the power law index, we investigate the dependence of PADs on electron kinetic energy, magnetic local time (MLT), the geomagnetic Kp index and L-shell. The differ ...

Shi, Run; Summers, Danny; Ni, Binbin; Fennell, Joseph; Blake, Bernard; Spence, Harlan; Reeves, Geoffrey;

YEAR: 2015     DOI: 10.1002/2015JA021724

pitch angle distributions; Van Allen Probes

Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definit ...

Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q.-G.; Zhou, X.-Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y.-X.; Gao, Zhonglei; He, Zhaoguo; Baker, D.; Spence, H.; Reeves, G.; Blake, J.; Wygant, J.;

YEAR: 2015     DOI: 10.1038/ncomms10096

Van Allen Probes

Wave-particle interactions in the outer radiation belts

Data from the Van Allen Probes have provided the first extensive evidence of non-linear (as opposed to quasi-linear) wave-particle interactions in space, with the associated rapid (fraction of a bounce period) electron acceleration, to hundreds of keV by Landau resonance, in the parallel electric fields of time domain structures (TDS) and very oblique chorus waves. The experimental evidence, simulations, and theories of these processes are discussed.

Agapitov, O.~V.; Mozer, F.~S.; Artemyev, A.~V.; Mourenas, D.; Krasnoselskikh, V.~V.;

YEAR: 2015     DOI:

plasma waves and instabilities; Radiation belts; Van Allen Probes; Wave-particle interaction

Electron scattering by magnetosonic waves in the inner magnetosphere

We investigate the importance of electron scattering by magnetosonic waves in the Earth\textquoterights inner magnetosphere. A statistical survey of the magnetosonic wave amplitude and wave frequency spectrum, as a function of geomagnetic activity, is performed using the Van Allen Probes wave measurements, and is found to be generally consistent with the wave distribution obtained from previous spacecraft missions. Outside the plasmapause the statistical frequency distribution of magnetosonic waves follows the variation of t ...

Ma, Qianli; Li, Wen; Thorne, Richard; Bortnik, Jacob; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2015JA021992

Electron scattering; magnetosonic waves; Van Allen Probes; Van Allen Probes statistics

Empirical model of lower band chorus wave distribution in the outer radiation belt

Accurate modeling of wave-particle interactions in the radiation belts requires detailed information on wave amplitudes and wave-normal angular distributions over L shells, magnetic latitudes, magnetic local times, and for various geomagnetic activity conditions. In this work, we develop a new and comprehensive parametric model of VLF chorus waves amplitudes and obliqueness in the outer radiation belt using statistics of VLF measurements performed in the chorus frequency range during 10 years (2001\textendash2010) aboard the ...

Agapitov, O.; Artemyev, A.; Mourenas, D.; Mozer, F.; Krasnoselskikh, V.;

YEAR: 2015     DOI: 10.1002/2015JA021829

model for chorus wave

Energy dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions.

We present observations of the radiation belts from the HOPE and MagEIS particle detectors on the Van Allen Probes satellites that illustrate the energy-dependence and L-shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on March 1 in more detail. The observations show: (a) At all L-shells, lower-energy electrons are enhanced more often than higher energies; (b) Events that fill the slot region are more common at lower energies; (c) Enhancements of electrons in the inner ...

Reeves, Geoffrey; Friedel, Reiner; Larsen, Brian; Skoug, Ruth; Funsten, Herbert; Claudepierre, Seth; Fennell, Joseph; Turner, Drew; Denton, Mick; Spence, H.; Blake, Bernard; Baker, D.;

YEAR: 2015     DOI: 10.1002/2015JA021569

Acceleration; energetic particles; Inner zone; Outer Zone; Radiation belts; Slot region; Van Allen Probes

Evolution of lower hybrid turbulence in the ionosphere

Three-dimensional evolution of the lower hybrid turbulence driven by a spatially localized ion ring beam perpendicular to the ambient magnetic field in space plasmas is analyzed. It is shown that the quasi-linear saturation model breaks down when the nonlinear rate of scattering by thermal electron is larger than linear damping rates, which can occur even for low wave amplitudes. The evolution is found to be essentially a three-dimensional phenomenon, which cannot be accurately explained by two-dimensional simulations. An im ...

Ganguli, G.; Crabtree, C.; Mithaiwala, M.; Rudakov, L.; Scales, W.;

YEAR: 2015     DOI: 10.1063/1.4936281


Formation process of relativistic electron flux through interaction with chorus emissions in the Earth\textquoterights inner magnetosphere

We perform test particle simulations of energetic electrons interacting with whistler mode chorus emissions. We compute trajectories of a large number of electrons forming a delta function with the same energy and equatorial pitch angle. The electrons are launched at different locations along the magnetic field line and different timings with respect to a pair of chorus emissions generated at the magnetic equator. We follow the evolution of the delta function and obtain a distribution function in energy and equatorial pitch ...

Omura, Yoshiharu; Miyashita, Yu; Yoshikawa, Masato; Summers, Danny; Hikishima, Mitsuru; Ebihara, Yusuke; Kubota, Yuko;

YEAR: 2015     DOI: 10.1002/2015JA021563

Chorus; nonlinear wave-particle interaction; Particle acceleration; Radiation belts; relativistic electrons; simulation

Global Empirical Models of Plasmaspheric Hiss using Van Allen Probes

Plasmaspheric hiss is a whistler mode emission that permeates the Earth\textquoterights plasmasphere and is a significant driver of energetic electron losses through cyclotron-resonant pitch angle scattering. The EMFISIS instrument on the Van Allen Probes mission provides vastly improved measurements of the hiss wave environment including continuous measurements of the wave magnetic field cross-spectral matrix and enhanced low frequency coverage. Here, we develop empirical models of hiss wave intensity using two years of Van ...

Spasojevic, M.; Shprits, Y.Y.; Orlova, K.;

YEAR: 2015     DOI: 10.1002/2015JA021803

Electron scattering; Empirical Model; inner magnetosphere; Plasmaspheric Hiss; Van Allen Probes

High-resolution in situ observations of electron precipitation-causing EMIC waves

Electromagnetic ion cyclotron (EMIC) waves are thought to be important drivers of energetic electron losses from the outer radiation belt through precipitation into the atmosphere. While the theoretical possibility of pitch angle scattering-driven losses from these waves has been recognized for more than four decades, there have been limited experimental precipitation observations to support this concept. We have combined satellite-based observations of the characteristics of EMIC waves, with satellite and ground-based obser ...

Rodger, Craig; Hendry, Aaron; Clilverd, Mark; Kletzing, Craig; Brundell, James; Reeves, Geoffrey;

YEAR: 2015     DOI: 10.1002/grl.v42.2210.1002/2015GL066581

EMIC waves; energetic electron precipitation; radiation belt electrons; Van Allen Probes; wave-particle interactions

In-flight performance of the Van Allen Probes RF telecommunications system

The NASA Van Allen Probes mission (previously called the Radiation Belt Storm Probes) successfully launched on 30 August 2012. The twin spacecraft, designed, built, and operated by The Johns Hopkins University Applied Physics Laboratory (JHU/APL), has been successfully operating within Earth׳s radiation belts since then, returning critical science data revealing new insights into the physics of the radiation belts. Because of the extreme radiation environment, all spacecraft subsystems including the communications system ha ...

Srinivasan, Dipak; Adams, Norm; Wallis, Robert;

YEAR: 2015     DOI: 10.1016/j.actaastro.2015.05.001

Van Allen Probes

Kinetic Alfv\ en Waves and Particle Response Associated with a Shock-Induced, Global ULF Perturbation of the Terrestrial Magnetosphere

On 2 October 2013, the arrival of an interplanetary shock compressed the Earth\textquoterights magnetosphere and triggered a global ULF (ultra low frequency) oscillation. The Van Allen Probe B spacecraft observed this large-amplitude ULF wave in situ with both magnetic and electric field data. Broadband waves up to approximately 100 Hz were observed in conjunction with, and modulated by, this ULF wave. Detailed analysis of fields and particle data reveals that these broadband waves are Doppler-shifted kinetic Alfv\ en waves. ...

Malaspina, David; Claudepierre, Seth; Takahashi, Kazue; Jaynes, Allison; Elkington, Scot; Ergun, Robert; Wygant, John; Reeves, Geoff; Kletzing, Craig;

YEAR: 2015     DOI: 10.1002/2015GL065935

inner magnetosphere; interplanetary shock; Kinetic Alfven Waves; magnetosphere shock response; plasma waves; ULF waves; Van Allen Probes

Multifrequency compressional magnetic field oscillations and their relation to multiharmonic toroidal mode standing Alfv\ en waves

The power spectrum of the compressional component of magnetic fields observed by the Van Allen Probes spacecraft near the magnetospheric equator in the dayside plasmasphere sometimes exhibits regularly spaced multiple peaks at frequencies below 50 mHz. We show by detailed analysis of events observed on two separate days in early 2014 that the frequencies change smoothly with the radial distance of the spacecraft and appear at or very near the frequencies of the odd harmonics of mutiharmonic toroidal mode standing Alfv\ en wa ...

Takahashi, Kazue; Waters, Colin; Glassmeier, Karl-Heinz; Kletzing, Craig; Kurth, William; Smith, Charles;

YEAR: 2015     DOI: 10.1002/2015JA021780

Compressional oscillations; Field line resonance; Pc3-Pc4 band; plasmasphere; Van Allen Probes

Multiple loss processes of relativistic electrons outside the heart of outer radiation belt during a storm sudden commencement

By examining the compression-induced changes in the electron phase space density and pitch angle distribution observed by two satellites of Van Allen Probes (RBSP-A/B), we find that the relativistic electrons (>2MeV) outside the heart of outer radiation belt (L*>= 5) undergo multiple losses during a storm sudden commencement (SSC). The relativistic electron loss mainly occurs in the field-aligned direction (pitch angle α< 30\textdegree or >150\textdegree), and the flux decay of the field-aligned electrons is independent of ...

Yu, J.; Li, L.Y.; Cao, J.; Yuan, Z.; Reeves, G.; Baker, D.; Blake, J.; Spence, H.;

YEAR: 2015     DOI: 10.1002/2015JA021460

Electromagnetic ion cyclotron (EMIC) waves; outer radiation belt; Outward radial diffusion driven by ULF waves; Plasmaspheric Hiss; relativistic electron loss; Storm sudden commencement; Van Allen Probes

Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary (GEO) and medium Earth orbit (MEO). To provide alerts of electron flux enhancements, sixteen prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements ...

Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2015     DOI: 10.1002/2015SW001254

outer radiation belt; Practical prediction model; Van Allen Probes

Responses of relativistic electron fluxes in the outer radiation belt to geomagnetic storms

Geomagnetic storms can either increase or decrease relativistic electron fluxes in the outer radiation belt. A statistical survey of 84 isolated storms demonstrates that geomagnetic storms preferentially decrease relativistic electron fluxes at higher energies, while flux enhancements are more common at lower energies. In about 87\% of the storms, 0.3\textendash2.5 MeV electron fluxes show an increase, whereas 2.5\textendash14 MeV electron fluxes increase in only 35\% of the storms. Superposed epoch analyses suggest that suc ...

Xiong, Ying; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Chen, Lunjin; Ni, Binbin; Li, Wen; Li, Jinxing; Guo, Ruilong; Parks, G.;

YEAR: 2015     DOI: 10.1002/2015JA021440

energy dependence; Geomagnetic storm; Radiation belts; relativistic electrons; Solar wind

Electron distribution function formation in regions of diffuse aurora

The precipitation of high-energy magnetospheric electrons (E \~ 600 eV\textendash10 KeV) in the diffuse aurora contributes significant energy flux into the Earth\textquoterights ionosphere. To fully understand the formation of this flux at the upper ionospheric boundary, \~700\textendash800 km, it is important to consider the coupled ionosphere-magnetosphere system. In the diffuse aurora, precipitating electrons initially injected from the plasma sheet via wave-particle interaction processes degrade in the atmosphere toward ...

Khazanov, G.; Tripathi, A.; Sibeck, D.; Himwich, E.; Glocer, A.; Singhal, R.;

YEAR: 2015     DOI: 10.1002/2015JA021728

diffuse aurora; electron distribution; Wave-particle interaction

Estimation of pitch angle diffusion rates and precipitation time scales of electrons due to EMIC waves in a realistic field model

Electromagnetic ion cyclotron (EMIC) waves are closely related to precipitating loss of relativistic electrons in the radiation belts, and thereby, a model of the radiation belts requires inclusion of the pitch angle diffusion caused by EMIC waves. We estimated the pitch angle diffusion rates and the corresponding precipitation time scales caused by H and He band EMIC waves using the Tsyganenko 04 (T04) magnetic field model at their probable regions in terms of geomagnetic conditions. The results correspond to enhanced pitch ...

Bin Kang, Suk-; Min, Kyoung-Wook; Fok, Mei-Ching; Hwang, Junga; Choi, Cheong-Rim;

YEAR: 2015     DOI: 10.1002/2014JA020644

EMIC waves; pitch angle diffusion rate; precipitation time scale; quasi-linear theory; realistic field model; Relativistic electron

On the formation and origin of substorm growth phase/onset auroral arcs inferred from conjugate space-ground observations

Magnetotail processes and structures related to substorm growth phase/onset auroral arcs remain poorly understood mostly due to the lack of adequate observations. In this study we make a comparison between ground-based optical measurements of the premidnight growth phase/onset arcs at subauroral latitudes and magnetically conjugate measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) at ~780 km in altitude and by the Van Allen Probe B (RBSP-B) spacecraft crossing L values o ...

Motoba, T.; Ohtani, S.; Anderson, B.; Korth, H.; Mitchell, D.; Lanzerotti, L.; Shiokawa, K.; Connors, M.; Kletzing, C.; Reeves, G.;

YEAR: 2015     DOI: 10.1002/jgra.v120.1010.1002/2015JA021676

FACs; growth phase/onset arc; M-I coupling; Van Allen Probes

Giant pulsations on the afternoonside: Geostationary satellite and ground observations

Giant pulsations (Pgs) are a special class of oscillations recognized in ground magnetometer records as exhibiting highly regular sinusoidal waveforms in the east-west component with periods around 100s. Previous statistical studies showed that Pgs occur almost exclusively on the morningside with peak occurrence in the postmidnight sector. In this paper, we present observations of Pgs extending to the afternoonside, using data from the GOES13 and 15 geostationary satellites and multiple ground magnetometers located in North ...

Motoba, Tetsuo; Takahashi, Kazue; Rodriguez, Juan; Russell, Christopher;

YEAR: 2015     DOI: 10.1002/2015JA021592

giant pulsations; ground-space conjunction; wave-particle interactions

Heavy-ion dominance near Cluster perigees

Time periods in which heavy ions dominate over H+ in the energy range of 1-40 keV were observed by the Cluster Ion Spectrometry (CIS)/COmposition DIstribution Function (CODIF) instrument onboard Cluster Spacecraft 4 at L-values less than 4. The characteristic feature is a narrow flux peak at around 10 keV that extends into low L-values, with He+ and/or O+ dominating. In the present work we perform a statistical study of these events and examine their temporal occurrence and spatial distribution. The observed features, both t ...

Ferradas, C.; Zhang, J.-C.; Kistler, L.; Spence, H.;

YEAR: 2015     DOI: 10.1002/2015JA021063

charge exchange; Cluster; heavy ions; inner magnetosphere; plasma sheet; ring current

Local time distributions of repetition periods for rising tone lower band chorus waves in the magnetosphere

Whistler mode chorus waves generally occur outside the plasmapause in the magnetosphere. The most striking feature of the waves is their occurrence in discrete elements. One of the parameters that describe the discrete elements is the repetition period (Trp), the time between consecutive elements. The Trp has not been studied statistically before. We use high-resolution waveform data to derive distributions of Trp for different local times. We find that the average Trp for the nightside (0.56 s) and dawnside (0.53 s) are sma ...

Shue, Jih-Hong; Hsieh, Yi-Kai; W. Y. Tam, Sunny; Wang, Kaiti; Fu, Hui; Bortnik, Jacob; Tao, Xin; Hsieh, Wen-Chieh; Pi, Gilbert;

YEAR: 2015     DOI: 10.1002/2015GL066107

Chorus; local time distribution; repetition period

Measurement of inner radiation belt electrons with kinetic energy above 1~MeV

Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992\textendash2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electron ...

Selesnick, R.;

YEAR: 2015     DOI: 10.1002/2015JA021387

electrons; Inner zone; Radiation belt

Thermal electron acceleration by electric field spikes in the outer radiation belt: Generation of field-aligned pitch angle distributions

Van Allen Probes observations in the outer radiation belt have demonstrated an abundance of electrostatic electron-acoustic double layers (DL). DLs are frequently accompanied by field-aligned (bidirectional) pitch angle distributions (PAD) of electrons with energies from hundred eVs up to several keV. We perform numerical simulations of the DL interaction with thermal electrons making use of the test particle approach. DL parameters assumed in the simulations are adopted from observations. We show that DLs accelerate thermal ...

. Y. Vasko, I; Agapitov, O.; Mozer, F.; Artemyev, A.;

YEAR: 2015     DOI: 10.1002/2015JA021644

double layers; Fermi mechanism; field-aligned pitch angle distributions; outer radiation belt; thermal electron acceleration; Van Allen Probes

\textquotedblleftTrunk-like\textquotedblright heavy ion structures observed by the Van Allen Probes

Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. We report \textquotedbllefttrunk-like\textquotedblright ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant\textquoterights trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He+ and O+ ions but not in H+. During the event, ion energ ...

Zhang, J.-C.; Kistler, L.; Spence, H.; Wolf, R.; Reeves, G.; Skoug, R.; Funsten, H.; Larsen, B.; Niehof, J.; MacDonald, E.; Friedel, R.; Ferradas, C.; Luo, H.;

YEAR: 2015     DOI: 10.1002/2015JA021822

inner magnetosphere; ion injection; Ion structure; magnetic cloud; magnetic storm; Van Allen Probes

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations

Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth\textquoterights radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution, or the limited in-situ satellite wave measurements from satellites. This paper evaluates the performance and limitations of a novel technique capa ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2015     DOI: 10.1002/2015JA021148

Plasmaspheric Hiss; Van Allen Probes; wave-particle interactions; Waves global model

First joint in situ and global observations of the medium-energy oxygen and hydrogen in the inner magnetosphere

We present the first simultaneous observations of the in situ ions and global Energetic Neutral Atom (ENA) images of the composition-separated, medium-energy (~1\textendash50 keV) particle populations of the inner magnetosphere. The ENA emissions are mapped into L shell/magnetic local time space based on the exospheric density along the line of sight (LOS). The ENA measurement can then be scaled to determine an average ion flux along a given LOS. The in situ ion flux tends to be larger than the scaled ENAs at the same local ...

Valek, P.; Goldstein, J.; Jahn, J.-M.; McComas, D.; Spence, H.;

YEAR: 2015     DOI: 10.1002/2015JA021151

ENAs; oxygen; storms; TWINS; Van Allen Probes

Internal Charging Hazards in Near-Earth Space during Solar Cycle 24 Maximum: Van Allen Probes Measurements

The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. Data from the MagEIS suite of sensors measures energy spectra, fluxes, and yields electron deposition rates that can cause internal charging. We use omni-directional fluxes of electrons and protons to calculate the dose under varying materials and thicknesses of shielding (similar to Fennell et al., 2010). We show examples of cha ...

Skov, Mulligan; Fennell, J.F.; Roeder, J.L.; Blake, J.B.; Claudepierre, S.G.;

YEAR: 2015     DOI: 10.1109/TPS.2015.2468214

Van Allen Probes

Internal Charging Hazards in Near-Earth Space During Solar Cycle 24 Maximum: Van Allen Probes Measurements

The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. The MagEIS suite of sensors measures energy spectra and fluxes of charged particles in the space environment. The calculations show that these fluxes result in electron deposition rates high enough to cause internal charging. We use omnidirectional fluxes of electrons and protons to calculate the dose under varying materials and ...

Skov, Tamitha; Fennell, Joseph; Roeder, James; Blake, Bernard; Claudepierre, Seth;

YEAR: 2015     DOI: 10.1109/TPS.2015.2468214

artificial satellites; dielectric materials; electrons; Energy measurement; MAGEis; Magnetosphere; particle detectors; protons; Van Allen Probes

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