Bibliography



Found 121 entries in the Bibliography.


Showing entries from 1 through 50


2020

Radial Response of Outer Radiation Belt Relativistic Electrons During Enhancement Events at Geostationary Orbit

Abstract Forecasting relativistic electron fluxes at geostationary Earth orbit (GEO) has been a long-term goal of the scientific community, and significant advances have been made in the past, but the relation to the interior of the radiation belts, that is, to lower L-shells, is still not clear. In this work we have identified 60 relativistic electron enhancement events at GEO to study the radial response of outer belt fluxes and the correlation between the fluxes at GEO and those at lower L-shells. The enhancement events o ...

Pinto, Victor; Bortnik, Jacob; Moya, Pablo; Lyons, Larry; Sibeck, David; Kanekal, Shrikanth; Spence, Harlan; Baker, Daniel;

YEAR: 2020     DOI: 10.1029/2019JA027660

Radiation belts; relativistic electrons; geosynchronous orbit; Outer Belt; flux correlation; enhancement events; Van Allen Probes

Analysis of Electric and Magnetic Lightning-Generated Wave Amplitudes Measured by the Van Allen Probes

Abstract We provide a statistical analysis of both electric and magnetic field wave amplitudes of very low frequency lightning-generated waves (LGWs) based on the equivalent of 11.5 years of observations made by the Van Allen Probes encompassing ~24.6 × 106 survey mode measurements. We complement this analysis with data from the ground-based World Wide Lightning Location Network to explore differences between satellite and ground-based measurements. LGW mean amplitudes are found to be low compared with other whistler mod ...

Ripoll, J.-F.; Farges, T.; Malaspina, D.; Lay, E.; Cunningham, G.; Hospodarsky, G.; Kletzing, C.; Wygant, J.;

YEAR: 2020     DOI: 10.1029/2020GL087503

lightning-generated waves; electric wave power; magnetic wave power; WWLLN database; Radiation belts; Van Allen Probes

2019

Decay of Ultrarelativistic Remnant Belt Electrons Through Scattering by Plasmaspheric Hiss

Ultrarelativistic electron remnant belts appear frequently following geomagnetic disturbances and are located in-between the inner radiation belt and a reforming outer belt. As remnant belts are relatively stable, here we explore the importance of hiss and electromagnetic ion cyclotron waves in controlling the observed decay rates of remnant belt ultrarelativistic electrons in a statistical way. Using measurements from the Van Allen Probes inside the plasmasphere for 25 remnant belt events that occurred between 2012 and 2017 ...

Pinto, V.; Mourenas, D.; Bortnik, J.; Zhang, X.-J.; Artemyev, A.; Moya, P.; Lyons, L.;

YEAR: 2019     DOI: 10.1029/2019JA026509

Decay rates; EMIC waves; MeV Electron Decay; Plasmaspheric Hiss; Radiation belts; Remnant Belt; Van Allen Probes

Evolution of Pitch Angle-Distributed Megaelectron Volt Electrons During Each Phase of the Geomagnetic Storm

Using Relativistic Electron Proton Telescope measurements onboard Van Allen Probes, the evolution of electron pitch angle distributions (PADs) during the different phases of magnetic storms is studied. Electron fluxes are sorted in terms of storm phase, urn:x-wiley:jgra:media:jgra55457:jgra55457-math-0001 value, energy, and magnetic local time (MLT) sectors for 55 magnetic storms from October 2012 through May 2017. To understand the potential mechanisms for the evolution of electron PADs, we fit PADs to a sinusoidal function ...

Pandya, Megha; Bhaskara, Veenadhari; Ebihara, Yusuke; Kanekal, Shrikanth; Baker, Daniel;

YEAR: 2019     DOI: 10.1029/2019JA027086

electron flux; inner magnetosphere; Pitch angle distribution; Radiation belts; Van Allen Probes

Particle Dynamics in the Earth\textquoterights Radiation Belts: Review of Current Research and Open Questions

The past decade transformed our observational understanding of energetic particle processes in near-Earth space. An unprecedented suite of observational systems were in operation including the Van Allen Probes, Arase, MMS, THEMIS, Cluster, GPS, GOES, and LANL-GEO magnetospheric missions. They were supported by conjugate low-altitude measurements on spacecraft, balloons, and ground-based arrays. Together these significantly improved our ability to determine and quantify the mechanisms that control the build-up and subsequent ...

Ripoll, Jean-Francois; Claudepierre, Seth; Ukhorskiy, Sasha; Colpitts, Chris; Li, Xinlin; Fennell, Joe; Crabtree, Chris;

YEAR: 2019     DOI: 10.1029/2019JA026735

inner magnetosphere; laboratory plasma experiments; Particle acceleration; particle loss; Radiation belts; Van Allen Probes

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

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

YEAR: 2019     DOI: 10.1029/2019JA027331

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

Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves

Electromagnetic ion cyclotron (EMIC) waves are known to typically cause electron losses into Earth\textquoterights upper atmosphere at >~1 MeV, while the minimum energy of electrons subject to efficient EMIC-driven precipitation loss is unresolved. This letter reports electron precipitation from subrelativistic energies of ~250 keV up to ~1 MeV observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD-II) CubeSats, while two Polar Operational Environmental Satellites (POES) ...

Capannolo, L.; Li, W.; Ma, Q.; Chen, L.; Shen, X.-C.; Spence, H.; Sample, J.; Johnson, A.; Shumko, M.; Klumpar, D.; Redmon, R.;

YEAR: 2019     DOI: 10.1029/2019GL084202

electron precipitation; EMIC waves; FIREBIRD-II; quasi linear theory; Radiation belts; Van Allen Probes; wave particle interactions

Earth\textquoterights Van Allen Radiation Belts: From Discovery to the Van Allen Probes Era

Discovery of the Earth\textquoterights Van Allen radiation belts by instruments flown on Explorer 1 in 1958 was the first major discovery of the Space Age. The observation of distinct inner and outer zones of trapped megaelectron volt (MeV) particles, primarily protons at low altitude and electrons at high altitude, led to early models for source and loss mechanisms including Cosmic Ray Albedo Neutron Decay for inner zone protons, radial diffusion for outer zone electrons and loss to the atmosphere due to pitch angle scatter ...

Li, W.; Hudson, M.K.;

YEAR: 2019     DOI: 10.1029/2018JA025940

Particle acceleration; particle loss; particle transport; Radiation belts; Van Allen Probes; wave-particle interactions

Storm Time Depletions of Multi-MeV Radiation Belt Electrons Observed at Different Pitch Angles

During geomagnetic storms, the rapid depletion of the high-energy (several MeV) outer radiation belt electrons is the result of loss to the interplanetary medium through the magnetopause, outward radial diffusion, and loss to the atmosphere due to wave-particle interactions. We have performed a statistical study of 110 storms using pitch angle resolved electron flux measurements from the Van Allen Probes mission and found that inside of the radiation belt (L* = 3 - 5) the number of storms that result in depletion of electron ...

. Y. Drozdov, A; Aseev, N.; Effenberger, F.; Turner, D.; Saikin, A.; . Y. Shprits, Y;

YEAR: 2019     DOI: 10.1029/2019JA027332

EMIC waves; multi-MeV electrons; Radiation belts; Van Allen Probes

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

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

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

YEAR: 2019     DOI: 10.1029/2019JA027111

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

RBSP-ECT Combined Spin-Averaged Electron Flux Data Product

We describe a new data product combining the spin-averaged electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration\textquoterights Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of spectra for September 2013 to the present. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data produ ...

Boyd, A.; Reeves, G.; Spence, H.; Funsten, H.; Larsen, B.; Skoug, R.; Blake, J.; Fennell, J.; Claudepierre, S.; Baker, D.; Kanekal, S.; Jaynes, A.;

YEAR: 2019     DOI: 10.1029/2019JA026733

ECT; HOPE; MAGEis; Radiation belts; REPT; 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

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

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

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

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

Outer Van Allen Radiation Belt Response to Interacting Interplanetary Coronal Mass Ejections

We study the response of the outer Van Allen radiation belt during an intense magnetic storm on 15\textendash22 February 2014. Four interplanetary coronal mass ejections (ICMEs) arrived at Earth, of which the three last ones were interacting. Using data from the Van Allen Probes, we report the first detailed investigation of electron fluxes from source (tens of kiloelectron volts) to core (megaelectron volts) energies and possible loss and acceleration mechanisms as a response to substructures (shock, sheath and ejecta, and ...

Kilpua, E.; Turner, D.; Jaynes, A.; Hietala, H.; Koskinen, H.; Osmane, A.; Palmroth, M.; Pulkkinen, T.; Vainio, R.; Baker, D.; Claudepierre, S.;

YEAR: 2019     DOI: 10.1029/2018JA026238

interplanetary coronal mass ejections; magnetospheric storm; magnetospheric waves; Outer Belt; Radiation belts; Solar wind; Van Allen Probes

Contribution of ULF wave activity to the global recovery of the outer radiation belt during the passage of a high-speed solar wind stream observed in September 2014

Energy coupling between the solar wind and the Earth\textquoterights magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how Ultra Low Frequency (ULF) wave activity during the passage of Alfv\ enic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To in ...

Da Silva, L.; Sibeck, D.; Alves, L.; Souza, V.; Jauer, P.; Claudepierre, S.; Marchezi, J.; Agapitov, O.; Medeiros, C.; Vieira, L.; Wang, C.; Jiankui, S.; Liu, Z.; Gonzalez, W.; Dal Lago, A.; Rockenbach, M.; Padua, M.; Alves, M.; Barbosa, M.; Fok, M.-C.; Baker, D.; Kletzing, C.; Kanekal, S.; Georgiou, M.;

YEAR: 2019     DOI: 10.1029/2018JA026184

alfv\ en fluctuations; Earth\textquoterights magnetosphere; high speed stream; Radiation belts; relativistic electron flux; ULF wave; Van Allen Probes

Electron intensity measurements by the Cluster/RAPID/IES instrument in Earth\textquoterights radiation belts and ring current

The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earth\textquoterights magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high-energy electrons (<400 keV) and inner-zone protons (230-630 keV) in the radiation belts and ring current, the data have been rarely used for inner-magnetospheric science. The current paper presents two ...

Smirnov, A.; Kronberg, E.; Latallerie, F.; Daly, P.; Aseev, N.; . Y. Shprits, Y; Kellerman, A.; Kasahara, S.; Turner, D.; Taylor, M.;

YEAR: 2019     DOI: 10.1029/2018SW001989

electrons; Radiation belts; Solar Cycle; Space weather; Van Allen Probes

The Response of Earth\textquoterights Electron Radiation Belts to Geomagnetic Storms: Statistics From the Van Allen Probes Era Including Effects From Different Storm Drivers

A statistical study was conducted of Earth\textquoterights radiation belt electron response to geomagnetic storms using NASA\textquoterights Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L-shell, energy, and epoch time during 110 storms with SYM-H <=-50 nT during September 2012 to September 2017 (inclusive). The radiation belt response revealed clear energy and L-shell dependencies, with tens of keV electrons enhanced at all L-shells (2.5 ...

Turner, D.; Kilpua, E.; Hietala, H.; Claudepierre, S.; O\textquoterightBrien, T.; Fennell, J.; Blake, J.; Jaynes, A.; Kanekal, S.; Baker, D.; Spence, H.; Ripoll, J.-F.; Reeves, G.;

YEAR: 2019     DOI: 10.1029/2018JA026066

energetic particles; Geomagnetic storms; inner magnetosphere; Radiation belts; relativistic electrons; Van Allen Probes; wave-particle interactions

2018

Observations and Fokker-Planck simulations of the L-shell, energy, and pitch-angle structure of Earth\textquoterights electron radiation belts during quiet times

The evolution of the radiation belts in L-shell (L), energy (E), and equatorial pitch-angle (α0) is analyzed during the calm 11-day interval (March 4 \textendashMarch 15) following the March 1 storm 2013. Magnetic Electron and Ion Spectrometer (MagEIS) observations from Van Allen Probes are interpreted alongside 1D and 3D Fokker-Planck simulations combined with consistent event-driven scattering modeling from whistler mode hiss waves. Three (L, E, α0)-regions persist through 11 days of hiss wave scattering; the pitch-angle ...

Ripoll, -F.; Loridan, V.; Denton, M.; Cunningham, G.; Reeves, G.; ik, O.; Fennell, J.; Turner, D.; . Y. Drozdov, A; Villa, J.; . Y. Shprits, Y; Thaller, S.; Kurth, W.; Kletzing, C.; Henderson, M.; . Y. Ukhorskiy, A;

YEAR: 2018     DOI: 10.1029/2018JA026111

electron lifetime; hiss waves; pitch-angle diffusion coefficient; Radiation belts; Van Allen Probes; wave particle interactions

The outer radiation belt response to the storm time development of seed electrons and chorus wave activity during CME and CIR storms

Gyroresonant wave-particle interactions with very low frequency whistler mode chorus waves can accelerate subrelativistic seed electrons (hundreds of keV) to relativistic energies in the outer radiation belt during geomagnetic storms. In this study, we conduct a superposed epoch analysis of the chorus wave activity, the seed electron development, and the outer radiation belt electron response between L* = 2.5 and 5.5, for 25 coronal mass ejection and 35 corotating interaction region storms using Van Allen Probes observations ...

Bingham, S.; Mouikis, C.; Kistler, L.; Boyd, A.; Paulson, K.; Farrugia, C.; Huang, C.; Spence, H.; Claudepierre, S.; Kletzing, C.;

YEAR: 2018     DOI: 10.1029/2018JA025963

CIR storms; CME storms; Radiation belts; seed electrons; Van Allen Probes; VLF waves

Determination of the Equatorial Electron Differential Flux From Observations at Low Earth Orbit

Variations in the high-energy relativistic electron flux of the radiation belts depend on transport, acceleration, and loss processes, and importantly on the lower-energy seed population. However, data on the seed population is limited to a few satellite missions. Here we present a new method that utilizes data from the Medium Energy Proton/Electron Detector on board the low-altitude Polar Operational Environmental Satellites to retrieve the seed population at a pitch angle of 90\textdegree. The integral flux values measured ...

Allison, Hayley; Horne, Richard; Glauert, Sarah; Del Zanna, Giulio;

YEAR: 2018     DOI: 10.1029/2018JA025786

electrons; integral flux; Radiation belts; seed population; Van Allen Probes

Characteristics, Occurrence and Decay Rates of Remnant Belts associated with Three-Belt events in the Earth\textquoterights Radiation Belts

Shortly after the launch of the Van Allen Probes, a new three-belt configuration of the electron radiation belts was reported. Using data between September 2012 and November 2017, we have identified 30 three-belt events and found that about 18\% of geomagnetic storms result in such configuration. Based on the identified events, we evaluated some characteristics of the remnant (intermediate) belt. We determined the energy range of occurrence and found it peaks at E = 5.2 MeV. We also determined that the magnetopause location ...

Pinto, V\; Bortnik, Jacob; Moya, Pablo; Lyons, Larry; Sibeck, David; Kanekal, Shrikanth; Spence, Harlan; Baker, Daniel;

YEAR: 2018     DOI: 10.1029/2018GL080274

Belt Formation; MeV Electrons; Outer Belt; Radiation belts; Remnant Belt; Three Belts; Van Allen Probes

Diagnosis of ULF Wave-Particle Interactions With Megaelectron Volt Electrons: The Importance of Ultrahigh-Resolution Energy Channels

Electron flux measurements are an important diagnostic for interactions between ultralow-frequency (ULF) waves and relativistic (\~1 MeV) electrons. Since measurements are collected by particle detectors with finite energy channel width, they are affected by a phase mixing process that can obscure these interactions. We demonstrate that ultrahigh-resolution electron measurements from the Magnetic Electron Ion Spectrometer on the Van Allen Probes mission\textemdashobtained using a data product that improves the energy resolut ...

Hartinger, M.; Claudepierre, S.; Turner, D.; Reeves, G.; Breneman, A.; Mann, I.; Peek, T.; Chang, E.; Blake, J.; Fennell, J.; O\textquoterightBrien, T.; Looper, M.;

YEAR: 2018     DOI: 10.1029/2018GL080291

drift resonance; particle detector; Pc5; Radiation belts; ULF wave; Van Allen Probes; Wave-particle interaction

An event on simultaneous amplification of exohiss and chorus waves associated with electron density enhancements

Whistler mode exohiss are the structureless hiss waves observed outside the plasmapause with featured equatorward Poynting flux. An event of the amplification of exohiss as well as chorus waves was recorded by Van Allen Probes during the recovery phase of a weak geomagnetic storm. Amplitudes of both types of the waves showed a significant increase at the regions of electron density enhancements. It is found that the electrons resonant with exohiss and chorus showed moderate pitch-angle anisotropies. The ratio of the number o ...

Zhu, Hui; Shprits, Yuri; Chen, Lunjin; Liu, Xu; Kellerman, Adam;

YEAR: 2018     DOI: 10.1029/2017JA025023

electromagnetic waves; Exohiss; linear theory; Radiation belts; Van Allen Probes

Impact of Background Magnetic Field for EMIC Wave-Driven Electron Precipitation

Wave-particle interaction between relativistic electrons and electromagnetic ion cyclotron (EMIC) waves is a highly debated loss process contributing to the dynamics of Earth\textquoterights radiation belts. Theoretical studies show that EMIC waves can result in strong loss of relativistic electrons in the radiation belts (Summers \& Thorne, 2003, https://doi.org/10.1029/2002JA009489). However, many of these studies have not been validated by observations. Li et al. (2014, https://doi.org/10.1002/2014GL062273) modeled the re ...

Woodger, L.; Millan, R.; Li, Z.; Sample, J.;

YEAR: 2018     DOI: 10.1029/2018JA025315

electron precipitation; EMIC waves; Radiation belts; Van Allen Probes

Fast diffusion of ultra-relativistic electrons in the outer radiation belt: 17 March 2015 storm event

Inward radial diffusion driven by ULF waves has long been known to be capable of accelerating radiation belt electrons to very high energies within the heart of the belts, but more recent work has shown that radial diffusion values can be highly event-specific and mean values or empirical models may not capture the full significance of radial diffusion to acceleration events. Here we present an event of fast inward radial diffusion, occurring during a period following the geomagnetic storm of 17 March 2015. Ultra-relativisti ...

Jaynes, A.; Ali, A.; Elkington, S.; Malaspina, D.; Baker, D.; Li, X.; Kanekal, S.; Henderson, M.; Kletzing, C.; Wygant, J.;

YEAR: 2018     DOI: 10.1029/2018GL079786

Magnetosphere; radial diffusion; Radiation belts; ULF waves; Van Allen Probes

Pitch Angle Scattering and Loss of Radiation Belt Electrons in Broadband Electromagnetic Waves

A magnetic conjunction between Van Allen Probes spacecraft and the Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL) reveals the simultaneous occurrence of broadband Alfv\ enic fluctuations and multi-timescale modulation of enhanced atmospheric X-ray bremsstrahlung emission. The properties of the Alfv\ enic fluctuations are used to build a model for pitch angle scattering in the outer radiation belt on electron gyro-radii scale field structures. It is shown that this scattering may lead to the transport ...

Chaston, C.; Bonnell, J.; Halford, A.; Reeves, G.; Baker, D.; Kletzing, C.; Wygant, J.;

YEAR: 2018     DOI: 10.1029/2018GL079527

Alfven waves; drift-bounce resonance; energetic particles; Geomagnetic storms; pitch-angle scattering; Radiation belts; Van Allen Probes

Variation in Plasmaspheric Hiss Wave Power With Plasma Density

Plasmaspheric hiss waves are commonly observed in the inner magnetosphere. These waves efficiently scatter electrons, facilitating their precipitation into the atmosphere. Predictive inner magnetosphere simulations often model hiss waves using parameterized empirical maps of observed hiss power. These maps nearly always include parameterization by magnetic L value. In this work, data from the Van Allen Probes are used to compare variation in hiss wave power with variation in both L value and cold plasma density. It is found ...

Malaspina, David; Ripoll, Jean-Francois; Chu, Xiangning; Hospodarsky, George; Wygant, John;

YEAR: 2018     DOI: 10.1029/2018GL078564

inner magnetosphere; Plasmaspheric Hiss; Radiation belts; Van Allen Probes; Wave models

Nonlinear drift resonance between charged particles and ultra-low frequency waves: Theory and Observations

In Earth\textquoterights inner magnetosphere, electromagnetic waves in the ultra-low frequency (ULF) range play an important role in accelerating and diffusing charged particles via drift resonance. In conventional drift-resonance theory, linearization is applied under the assumption of weak wave-particle energy exchange so particle trajectories are unperturbed. For ULF waves with larger amplitudes and/or durations, however, the conventional theory becomes inaccurate since particle trajectories are strongly perturbed. Here, ...

Li, Li; Zhou, Xu-Zhi; Omura, Yoshiharu; Wang, Zi-Han; Zong, Qiu-Gang; Liu, Ying; Hao, Yi-Xin; Fu, Sui-Yan; Kivelson, Margaret; Rankin, Robert; Claudepierre, Seth; Wygant, John;

YEAR: 2018     DOI: 10.1029/2018GL079038

drift resonance; nonlinear process; Particle acceleration; Radiation belts; ULF waves; Van Allen Probes; wave-particle interactions

Understanding the Driver of Energetic Electron Precipitation Using Coordinated Multisatellite Measurements

Magnetospheric plasma waves play a significant role in ring current and radiation belt dynamics, leading to pitch angle scattering loss and/or stochastic acceleration of the particles. During a non-storm time dropout event on 24 September 2013, intense electromagnetic ion cyclotron (EMIC) waves were detected by Van Allen Probe A (Radiation Belt Storm Probes-A). We quantitatively analyze a conjunction event when Van Allen Probe A was located approximately along the same magnetic field line as MetOp-01, which detected simultan ...

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

YEAR: 2018     DOI: 10.1029/2018GL078604

EMIC waves; energetic particle precipitation; pitch angle scattering; Radiation belts; Van Allen Probes; wave particle interactions

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

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

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

YEAR: 2018     DOI: 10.1029/2018GL078582

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

Electron Distributions in Kinetic Scale Field Line Resonances: A Comparison of Simulations and Observations

Observations in kinetic scale field line resonances, or eigenmodes of the geomagnetic field, reveal highly field-aligned plateaued electron distributions. By combining observations from the Van Allen Probes and Cluster spacecraft with a hybrid kinetic gyrofluid simulation we show how these distributions arise from the nonlocal self-consistent interaction of electrons with the wavefield. This interaction is manifested as electron trapping in the standing wave potential. The process operates along most of the field line and qu ...

Damiano, P.A.; Chaston, C.C.; Hull, A.J.; Johnson, J.R.;

YEAR: 2018     DOI: 10.1029/2018GL077748

Alfven waves; field line resonances; kinetic effects; numerical modeling; particle trapping; Radiation belts; Van Allen Probes

Determining the mode, frequency, and azimuthal wave number of ULF waves during a HSS and moderate geomagnetic storm

Ultra-low frequency (ULF) waves play a fundamental role in the dynamics of the inner-magnetosphere and outer radiation belt during geomagnetic storms. Broadband ULF wave power can transport energetic electrons via radial diffusion and discrete ULF wave power can energize electrons through a resonant interaction. Using observations from the Magnetospheric Multiscale (MMS) mission, we characterize the evolution of ULF waves during a high-speed solar wind stream (HSS) and moderate geomagnetic storm while there is an enhancement ...

Murphy, Kyle; Inglis, Andrew; Sibeck, David; Rae, Jonathan; Watt, Clare; Silveira, Marcos; Plaschke, Ferdinand; Claudepierre, Seth; Nakamura, Rumi;

YEAR: 2018     DOI: 10.1029/2017JA024877

azimuthal wave number; Geomagnetic storms; mode structure; Radiation belts; ULF waves; Van Allen Probes

Electron nonlinear resonant interaction with short and intense parallel chorus wave-packets

One of the major drivers of radiation belt dynamics, electron resonant interaction with whistler-mode chorus waves, is traditionally described using the quasi-linear diffusion approximation. Such a description satisfactorily explains many observed phenomena, but its applicability can be justified only for sufficiently low intensity, long duration waves. Recent spacecraft observations of a large number of very intense lower band chorus waves (with magnetic field amplitudes sometimes reaching \~1\% of the background) therefore ...

Mourenas, D.; Zhang, X.-J.; Artemyev, A.; Angelopoulos, V.; Thorne, R.; Bortnik, J.; Neishtadt, A.; Vasiliev, A.;

YEAR: 2018     DOI: 10.1029/2018JA025417

chorus waves; ; kinetic equation; nonlinear interaction; Radiation belts; short wave-packets; trapping; Van Allen Probes

Global model of plasmaspheric hiss from multiple satellite observations

We present a global model of plasmaspheric hiss, using data from eight satellites, extending the coverage and improving the statistics of existing models. We use geomagnetic activity dependent templates to separate plasmaspheric hiss from chorus. In the region 22-14 MLT the boundary between plasmaspheric hiss and chorus moves to lower L* values with increasing geomagnetic activity. The average wave intensity of plasmaspheric hiss is largest on the dayside and increases with increasing geomagnetic activity from midnight throu ...

Meredith, Nigel; Horne, Richard; Kersten, Tobias; Li, Wen; Bortnik, Jacob; Sicard-Piet, elica; Yearby, Keith;

YEAR: 2018     DOI: 10.1029/2018JA025226

plasmasphere; Plasmaspheric Hiss; Radiation belts; Van Allen Probes

The global statistical response of the outer radiation belt during geomagnetic storms

Using the total radiation belt electron content calculated from Van Allen Probe phase space density (PSD), the time-dependent and global response of the outer radiation belt during storms is statistically studied. Using PSD reduces the impacts of adiabatic changes in the main phase, allowing a separation of adiabatic and non-adiabatic effects, and revealing a clear modality and repeatable sequence of events in storm-time radiation belt electron dynamics. This sequence exhibits an important first adiabatic invariant (μ) depe ...

Murphy, Kyle; Watt, C.; Mann, Ian; Rae, Jonathan; Sibeck, David; Boyd, A.; Forsyth, C.; Turner, D.; Claudepierre, S.; Baker, D.; Spence, H.; Reeves, G.; Blake, J.; Fennell, J.;

YEAR: 2018     DOI: 10.1002/2017GL076674

Geomagnetic storms; magnetospheric dynamics; Radiation belts; Solar Wind-Magnetosphere Coupling; statistical analysis; Van Allen Probes

On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction

We present observations of very fast radiation belt loss as resolved using high-time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The timescale of these losses is revealed to be as short as \~0.5 - 2 hours during intense magnetic storms, with some storms demonstrating almost total loss on these timescales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the Se ...

Olifer, L.; Mann, I.; Morley, S.; Ozeke, L.; Choi, D.;

YEAR: 2018     DOI: 10.1029/2018JA025190

inner magnetosphere; magnetopause shadowing; Radiation belts; Van Allen Probes

A census of plasma waves and structures associated with an injection front in the inner magnetosphere

Now that observations have conclusively established that the inner magnetosphere is abundantly populated with kinetic electric field structures and nonlinear waves, attention has turned to quantifying the ability of these structures and waves to scatter and accelerate inner magnetospheric plasma populations. A necessary step in that quantification is determining the distribution of observed structure and wave properties (e.g. occurrence rates, amplitudes, spatial scales). Kinetic structures and nonlinear waves have broadband ...

Malaspina, David; Ukhorskiy, Aleksandr; Chu, Xiangning; Wygant, John;

YEAR: 2018     DOI: 10.1002/2017JA025005

Electron Injection; inner magnetosphere; Kinetic structures; Plasma Boundaries; plasma waves; Radiation belts; Van Allen Probes

Coordinates for Representing Radiation Belt Particle Flux

Fifty years have passed since the parameter \textquotedblleftL-star\textquotedblright was introduced in geomagnetically trapped particle dynamics. It is thus timely to review the use of adiabatic theory in present-day studies of the radiation belts, with the intention of helping to prevent common misinterpretations and the frequent confusion between concepts like \textquotedblleftdistance to the equatorial point of a field line,\textquotedblright McIlwain\textquoterights L-value, and the trapped particle\textquoterights adia ...

Roederer, Juan; Lejosne, ène;

YEAR: 2018     DOI: 10.1002/2017JA025053

adiabatic coordinates; Radiation belts; Van Allen Probes

Radiation belt \textquotedblleftdropouts\textquotedblright and drift-bounce resonances in broadband electromagnetic waves

Observations during the main phase of geomagnetic storms reveal an anti-correlation between the occurrence of broadband low frequency electromagnetic waves and outer radiation belt electron flux. We show that the drift-bounce motion of electrons in the magnetic field of these waves leads to rapid electron transport. For observed spectral energy densities it is demonstrated that the wave magnetic field can drive radial diffusion via drift-bounce resonance on timescales less than a drift orbit. This process may provide outward ...

Chaston, C.; Bonnell, J.; Wygant, J.; Reeves, G.; Baker, D.; Melrose, D.;

YEAR: 2018     DOI: 10.1002/2017GL076362

Alfven waves; Geomagnetic storms; Radial Transport; Radiation belts; Van Allen Probes

2017

Examining coherency scales, substructure, and propagation of whistler-mode chorus elements with Magnetospheric Multiscale (MMS)

Whistler-mode chorus waves are a naturally occurring electromagnetic emission observed in Earth\textquoterights magnetosphere. Here, for the first time, data from NASA\textquoterights Magnetospheric Multiscale (MMS) mission were used to analyze chorus waves in detail, including the calculation of chorus wave normal vectors, k. A case study was examined from a period of substorm activity around the time of a conjunction between the MMS constellation and NASA\textquoterights Van Allen Probes mission on 07 April 2016. Chorus wa ...

Turner, D.; Lee, J.; Claudepierre, S.; Fennell, J.; Blake, J.; Jaynes, A.; Leonard, T.; Wilder, F.; Ergun, R.; Baker, D.; Cohen, I.; Mauk, B.; Strangeway, R.; Hartley, D.; Kletzing, C.; Breuillard, H.; Le Contel, O.; Khotyaintsev, Yu; Torbert, R.; Allen, R.; Burch, J.; Santolik, O.;

YEAR: 2017     DOI: 10.1002/2017JA024474

chorus waves; inner magnetosphere; Magnetospheric multiscale; MMS; Radiation belts; Van Allen Probes

A Statistical Study of the Spatial Extent of Relativistic Electron Precipitation with Polar Orbiting Environmental Satellites.

Relativistic Electron Precipitation (REP) in the atmosphere can contribute significantly to electron loss from the outer radiation belts. In order to estimate the contribution to this loss, it is important to estimate the spatial extent of the precipitation region. We observed REP with the zenith pointing (0o) Medium Energy Proton Electron Detector (MEPED) on board Polar Orbiting Environmental Satellites (POES), for 15 years (2000-2014) and used both single and multi satellite measurements to estimate an average extent of th ...

Shekhar, Sapna; Millan, Robyn; Smith, David;

YEAR: 2017     DOI: 10.1002/2017JA024716

Magnetosphere; precipitation; Radiation belts; relativistic electrons; spatial scale of REP; Van Allen Probes; wave particle scattering

On the effect of geomagnetic storms on relativistic electrons in the outer radiation belt: Van Allen Probes observations

Using Van Allen Probes ECT-REPT observations we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion and no change in flux values depends strongly on L and energy. Enhancement events are more common for \~ 2 MeV electrons at L \~ 5, and the number of enhancement events decreases with increasing energy at any given L shell. However, considering th ...

Moya, Pablo.; Pinto, \; Sibeck, David; Kanekal, Shrikanth; Baker, Daniel;

YEAR: 2017     DOI: 10.1002/2017JA024735

Geomagnetic storms; Radiation belts; relativistic electrons; Van Allen Probes

Signatures of Ultrarelativistic Electron Loss in the Heart of the Outer Radiation Belt Measured by Van Allen Probes

Up until recently, signatures of the ultrarelativistic electron loss driven by electromagnetic ion cyclotron (EMIC) waves in the Earth\textquoterights outer radiation belt have been limited to direct or indirect measurements of electron precipitation or the narrowing of normalized pitch angle distributions in the heart of the belt. In this study, we demonstrate additional observational evidence of ultrarelativistic electron loss that can be driven by resonant interaction with EMIC waves. We analyzed the profiles derived from ...

Aseev, N.; . Y. Shprits, Y; . Y. Drozdov, A; Kellerman, A.; Usanova, M.; Wang, D.; Zhelavskaya, I.;

YEAR: 2017     DOI: 10.1002/2017JA024485

electron loss; EMIC waves; Radiation belts; ultrarelativistic electrons; Van Allen Probes; wave-particle interactions

Empirical radiation belt models: Comparison with in-situ data and implications for environment definition

The empirical AP8/AE8 model has been the de-facto Earth\textquoterights radiation belts engineering reference for decades. The need from the community for a better model incubated the development of AP9/AE9/SPM, which addresses several shortcomings of the old model. We provide additional validation of AP9/AE9 by comparing in-situ electron and proton data from Jason-2, POES, and the Van Allen Probes spacecraft with the 5th, 50th, and 95th percentiles from AE9/AP9 and with the model outputs from AE8/AP8. The relatively short d ...

Pich, Maria; Jun, Insoo; Evans, Robin;

YEAR: 2017     DOI: 10.1002/2017SW001612

Empirical Models; Radiation belts; Radiation effects; Van Allen Probes

Rapid loss of radiation belt relativistic electrons by EMIC waves

How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth\textquoterights outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here, on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the EMIC wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile ...

Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H.; Reeves, G.; Baker, D.; Wygant, J.;

YEAR: 2017     DOI: 10.1002/2017JA024169

electron loss; EMIC waves; pitch angle scattering; radial diffusion; Radiation belts; Van Allen Probes; Wave-particle interaction



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