Bibliography



Found 232 entries in the Bibliography.


Showing entries from 1 through 50


2021

Origin of Electron Boomerang Stripes: Statistical Study

Abstract In the outer radiation belt, localized ULF waves can interact with energetic electrons by drift resonance, leading to quasiperiodic oscillations. The oscillations in the pitch angle spectrum can be characterized by either boomerang-shaped or straight stripes. Previous studies have shown that boomerang-shaped stripes evolve from straight ones when electrons drift away from the localized wave interaction region. Based on the time-of-flight technique on the pitch angle-dependent drift velocity, the origin can be remote ...

Zhao, X.; Hao, Y.; Zong, Q.; Zhou, X.; Yue, Chao; Chen, X.; Liu, Y.; Liu, Z.-Y.; Blake, J.; Claudepierre, S.; Reeves, G.;

YEAR: 2021     DOI: https://doi.org/10.1029/2021GL093377

Localized ULF waves; Energetic Elctrons; drift resonance; Time-of-flight Technique; source region; boomerang-shaped stripes; Van Allen Probes

Sustained oxygen spectral gaps and their dynamic evolution in the inner magnetosphere

Abstract Van Allen Probes observations of ion spectra often show a sustained gap within a very narrow energy range throughout the full orbit. To understand their formation mechanism, we statistically investigate the characteristics of the narrow gaps for oxygen ions and find that they are most frequently observed near the noon sector with a peak occurrence rate of over 30\%. The magnetic moment (μ) of the oxygen ions in the gap shows a strong dependence on magnetic local time (MLT), with higher and lower μ in the morning a ...

Yue, Chao; Zhou, Xu-Zhi; Bortnik, Jacob; Zong, Qiu-Gang; Li, Yuxuan; Ren, Jie; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA029092

oxygen spectral gaps; corotational drift resonance; sustained gaps; drainage void; test particle simulations; Van Allen Probes

Evidence of Alfvenic Poynting flux as the primary driver of auroral motion during a geomagnetic substorm

Abstract Geomagnetic substorms are major energy transfer events where energy stored in the Earths magnetotail is released into the ionosphere. Substorm phenomena, including auroral activities, earthward Poynting flux, magnetic field dipolarization, etc, have been extensively studied. However, the complex interplay among them is not fully understood. In a fortuitous event on June 07, 2013, the twin Van Allen Probes (separated by 0.4 hour in local time) observed bursts of earthward Alfvenic Poynting flux in the vicinity of the ...

Tian, S.; Colpitts, C.; Wygant, J.; Cattell, C.; Ferradas, C.; Igl, A.; Larsen, B.; Reeves, G.; Donovan, E.;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA029019

Poynting flux; auroral physics; discrete arc; Dipolarization; Alfven waves; Van Allen Probes

Simultaneous observation of two isolated proton auroras at subauroral latitudes by a highly sensitive all-sky camera and Van Allen Probes

Abstract Isolated proton auroras (IPAs) appearing at subauroral latitudes are generated by energetic protons precipitating from the magnetosphere through interaction with electromagnetic ion cyclotron (EMIC) waves. An IPA thus indicates the spatial scale and temporal variation of wave–particle interactions in the magnetosphere. In this study, a unique event of simultaneous ground and magnetospheric satellite observations of two IPAs were conducted on March 16, 2015, using an all-sky imager at Athabasca, Canada and Van Alle ...

Nakmaura, Kohki; Shiokawa, Kazuo; Otsuka, Yuichi; Shinbori, Atsuki; Miyoshi, Yoshizumi; Connors, Martin; Spence, Harlan; Reeves, Geoff; Funsten, Herbert; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA029078

isolated proton aurora; Van Allen Probes

Multi-event Analysis of Plasma and Field Variations in Source of Stable Auroral Red (SAR) Arcs in Inner Magnetosphere during Non-storm-time Substorms

Abstract Stable auroral red (SAR) arcs are optical events with dominant 630.0-nm emission caused by low-energy electron heat flux into the topside ionosphere from the inner magnetosphere. SAR arcs are observed at subauroral latitudes and often occur during the recovery phase of magnetic storms and substorms. Past studies concluded that these low-energy electrons were generated in the spatial overlap region between the outer plasmasphere and ring-current ions and suggested that Coulomb collisions between plasmaspheric electro ...

Inaba, Yudai; Shiokawa, Kazuo; Oyama, Shin-Ichiro; Otsuka, Yuichi; Connors, Martin; Schofield, Ian; Miyoshi, Yoshizumi; Imajo, Shun; Shinbori, Atsuki; Gololobov, Artem; Kazama, Yoichi; Wang, Shiang-Yu; W. Y. Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Asamura, Kazushi; Yokota, Shoichiro; Kasahara, Satoshi; Keika, Kunihiro; Hori, Tomoaki; Matsuoka, Ayako; Kasahara, Yoshiya; Kumamoto, Atsushi; Matsuda, Shoya; Kasaba, Yasumasa; Tsuchiya, Fuminori; Shoji, Masafumi; Kitahara, Masahiro; Nakamura, Satoko; Shinohara, Iku; Spence, Harlan; Reeves, Geoff; MacDowall, Robert; Smith, Charles; Wygant, John; Bonnell, John;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA029081

SAR arc; Arase; RBSP; ring current; Non-storm-time substorm; Plasmapause; Van Allen Probes

Van Allen probe observations of disappearance, recovery and patchiness of plasmaspheric hiss following two consecutive interplanetary shocks: First results

Abstract We present, for the first time, a plasmaspheric hiss event observed by the Van Allen probes in response to two successive interplanetary shocks occurring within an interval of ∼2 hours on December 19, 2015. The first shock arrived at 16:16 UT and caused disappearance of hiss for ∼30 minutes. Combined effect of plasmapause crossing, significant Landau damping by suprathermal electrons and their gradual removal by magnetospheric compression led to the disappearance of hiss. Calculation of electron phase space dens ...

Chakraborty, S.; Chakrabarty, D.; Reeves, G.; Baker, D.; Claudepierre, S.; Breneman, A.; Hartley, D.; Larsen, B.;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028873

Plasmaspheric Hiss; Van Allen Probe; Interplanetary shocks; substorms; Whistlers; ULF waves; Van Allen Probes

RBSP-ECT Combined Pitch Angle Resolved Electron Flux Data Product

Abstract We describe a new data product combining pitch angle resolved 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 s Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of pitch-angle-resolved spectra for the entire Van Allen Probes mission. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 ...

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

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028637

Van Allen Probes; Radiation belts; ECT; MAGEis; REPT; HOPE

Observations of density cavities and associated warm ion flux enhancements in the inner magnetosphere

Abstract We present a statistical study of density cavities observed in the inner magnetosphere by the Van Allen Probes during four one-month periods: February 2013, July 2013, January 2014 and June 2014. These periods were chosen to allow the survey of all magnetic local times. We find that density cavities are a recurrent feature of the density profiles of in situ measurements in the inner magnetosphere. We further investigate the correlation between the density cavities and the enhancement of fluxes of warm ions with ener ...

Ferradas, C.; Boardsen, S.; Fok, M.-C.; Buzulukova, N.; Reeves, G.; Larsen, B.;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028326

Magnetosphere: inner; plasmasphere; magnetospheric configuration and dynamics; plasma waves and instabilities; plasma sheet; density cavity; cold ion heating; cold ions; warm Plasma cloak; Van Allen Probes

Investigation of small-scale electron density irregularities observed by the Arase and Van Allen Probes satellites inside and outside the plasmasphere

AbstractIn-situ electron density profiles obtained from Arase in the night magnetic local time (MLT) sector and from RBSP-B covering all MLTs are used to study the small-scale density irregularities present in the plasmasphere and near the plasmapause. Electron density perturbations with amplitudes > 10\% from background density and with time-scales less than 30-min are investigated here as the small-scale density irregularities. The statistical survey of the density irregularities is carried out using nearly two years of de ...

Thomas, Neethal; Shiokawa, Kazuo; Miyoshi, Yoshizumi; Kasahara, Yoshiya; Shinohara, Iku; Kumamoto, Atsushi; Tsuchiya, Fuminori; Matsuoka, Ayako; Kasahara, Satoshi; Yokota, Shoichiro; Keika, Kunihiro; Hori, Tomo; Asamura, Kazushi; Wang, Shiang-Yu; Kazama, Yoichi; Tam, Sunny; Chang, Tzu-Fang; Wang, Bo-Jhou; Wygant, John; Breneman, Aaron; Reeves, Geoff;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA027917

Electron density; small-scale density irregularities; plasmasphere; inner magnetosphere; Van Allen Probes; Arase

Multi-Point Observations of Quasiperiodic Emission Intensification and Effects on Energetic Electron Precipitation

AbstractThe two Van Allen Probes simultaneously recorded a coherently modulated quasiperiodic (QP) emission that persisted for 3 hours. The magnetic field pulsation at the locations of the two satellites showed a substantial difference, and their frequencies were close to but did not exactly match the repetition frequency of QP emissions for most of the time, suggesting that those coherent QP emissions probably originated from a common source, which then propagated over a broad area in the magnetosphere. The QP emissions wer ...

Li, Jinxing; Bortnik, Jacob; Ma, Qianli; Li, Wen; Shen, Xiaochen; Nishimura, Yukitoshi; An, Xin; Thaller, Scott; Breneman, Aaron; Wygant, John; Kurth, William; Hospodarsky, George; Hartley, David; Reeves, Geoffrey; Funsten, Herbert; Blake, Bernard; Spence, Harlan; Baker, Daniel;

YEAR: 2021     DOI: https://doi.org/10.1029/2020JA028484

quasiperiodic emissions; electron precipitation; Radiation belt; chorus waves; Van Allen Probes; ULF wave

2020

Equatorial pitch angle distributions of 1 – 50 keV electrons in Earth s inner magnetosphere: an empirical model based on the Van Allen Probes observations

Using seven years of data from the HOPE instrument on the Van Allen Probes, equatorial pitch angle distributions (PADs) of 1 – 50 keV electrons in Earth s inner magnetosphere are investigated statistically. An empirical model of electron equatorial PADs as a function of radial distance, magnetic local time, geomagnetic activity, and electron energy is constructed using the method of Legendre polynomial fitting. Model results show that most equatorial PADs of 1 – 10s of keV electrons in Earth s inner magnetosphere are pan ...

Zhao, H.; Friedel, R.; Chen, Y.; Baker, D.; Li, X.; Malaspina, D.; Larsen, B.; Skoug, R.; Funsten, H.; Reeves, G.; Boyd, A.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028322

Pitch angle distribution; energetic electrons; Earth s inner magnetosphere; Anisotropy; Chorus wave; statistical analysis; Van Allen Probes

Characteristics of Electron Precipitation During 40 Energetic Electron Injections Inferred via Subionospheric VLF Signal Propagation

Energetic electron injection events are associated with energetic electron precipitation (EEP) through possible resonant wave-particle interactions. Previous studies confirm the impacts of injection-driven precipitation on observed amplitude/phase of subionospheric VLF (very low frequency) signals transmitted from distant artificial transmitters. Currently, there are substantial uncertainties on precipitation characteristics and flux during injection events. In this work we study 40 injection events selected by Van Allen Pro ...

Ghaffari, R.; Cully, C.; Turner, D.; Reeves, G.;

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027233

Van Allen Probes

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Origin of Electron Boomerang Stripes: Localized ULF Wave-Particle Interactions

Ultralow frequency (ULF) wave-particle interactions play a significant role in the radiation belt dynamic process, during which drift resonance can accelerate and transport energetic electrons in the outer radiation belt. Observations of wave-electron drift resonance are characterized by quasiperiodic straight or “boomerang-shaped” stripes in the pitch angle spectrogram. Here we present an ULF wave event on 1 December 2015, during which both kinds stripes were observed by Van Allen Probes A and B, respectively. Using the ...

Zhao, X.; Hao, Y.; Zong, Q.-G.; Zhou, X.-Z.; Yue, Chao; Chen, X.; Liu, Y.; Blake, J.; Claudepierre, S.; Reeves, G.;

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

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

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

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

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

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

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

A Short-lived Three-Belt Structure for sub-MeV Electrons in the Van Allen Belts: Time Scale and Energy Dependence

In this study we focus on the radiation belt dynamics driven by the geomagnetic storms during September 2017. Besides the long-lasting three-belt structures of ultrarelativistic electrons (>2 MeV, existing for tens of days), which has been studied intensively during the Van Allen Probe era, it is found that magnetospheric electrons of hundreds of keVs can also have three-belt structures at similar L extent during storm time. Measurements of 500–800 keV electrons from MagEIS instrument onboard Van Allen Probes show double- ...

Hao, Y.; Zong, Q.-G.; Zhou, X.-Z.; Zou, H.; Rankin, R.; Sun, Y.; Chen, X.; Liu, Y.; . Y. Fu, S; Baker, D.; Spence, H.; Blake, J.; Reeves, G.; Claudepierre, S.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020JA028031

storage ring; three-belt structure; hiss wave; electron lifetime; Radial Transport; Van Allen Probes

Defining Radiation Belt Enhancement Events Based on Probability Distributions

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

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

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

Radiation belts; methods; geosynchronous; energetic particles; hazards; Solar Cycle; Van Allen Probes

Simultaneous Observations of Localized and Global Drift Resonance

In this study, we present Van Allen Probe observations showing that seed (hundreds of keV) and core ( 1 MeV) electrons can resonate with ultra-low-frequency (ULF) wave modes with distinctive m values simultaneously. An unusual electron energy spectrogram with double-banded resonant structure was recorded by energetic particle, composition, and thermal plasma (ECT)-magnetic electron ion spectrometer (MagEIS) and, meanwhile, boomerang stripes in pitch angle spectrogram appeared at the lower energy band. A localized drift reson ...

Hao, Y.; Zhao, X.; Zong, Q.-G.; Zhou, X.-Z.; Rankin, R.; Chen, X.; Liu, Y.; . Y. Fu, S; Blake, J.; Reeves, G.; Claudepierre, S.;

YEAR: 2020     DOI: https://doi.org/10.1029/2020GL088019

drift resonance; ULF waves; Radiation Belt Dynamics; boomerang stripes; azimuthal wave number; multiple resonances; Van Allen Probes

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

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

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

YEAR: 2020     DOI: 10.1029/2019JA027733

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

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

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

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

YEAR: 2020     DOI: 10.1029/2019JA027424

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

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

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

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

YEAR: 2020     DOI: https://doi.org/10.1029/2019JA027733

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

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

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

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

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

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

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

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

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

YEAR: 2020     DOI: 10.1029/2020GL086991

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

Determining plasmaspheric density from the upper hybrid resonance and from the spacecraft potential: How do they compare?

The plasmasphere is a critical region of the magnetosphere. It is important for the evolution of Earth\textquoterights radiation belts. Waves in the plasmasphere interior (hiss) and vicinity (EMIC, chorus) help control the acceleration and loss of radiation belt particles. Thus, understanding the extent, structure, content, and dynamics of the plasmasphere is crucial to understanding radiation belt losses. The Van Allen Probes mission uses two methods to determine the total plasma density. First, the upper hybrid resonance ( ...

Jahn, J.-M.; Goldstein, J.; Kurth, W.S.; Thaller, S.; De Pascuale, S.; Wygant, J.; Reeves, G.D.; Spence, H.E.;

YEAR: 2020     DOI: 10.1029/2019JA026860

cold plasma density; plasmasphere; spacecraft charging; Van Allen Probes; wave resonances

Episodic Occurrence of Field-Aligned Energetic Ions on the Dayside

The tens of kiloelectron volt ions observed in the ring current region at L ~ 3\textendash7 generally have pancake pitch angle distributions, that is, peaked at 90\textdegree. However, in this study, by using the Van Allen Probe observations on the dayside, unexpectedly, we have found that about 5\% time, protons with energies of ~30 to 50 keV show two distinct populations, having an additional field-aligned population overlapping with the original pancake population. The newly appearing field-aligned populations have higher ...

Yue, Chao; Bortnik, Jacob; Zou, Shasha; Nishimura, Yukitoshi; Foster, John; Coppeans, Thomas; Ma, Qianli; Zong, Qiugang; Hull, A.; Henderson, Mike; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2020     DOI: 10.1029/2019GL086384

Van Allen Probes

2019

Eastward Propagating Second Harmonic Poloidal Waves Triggered by Temporary Outward Gradient of Proton Phase Space Density: Van Allen Probe A Observation

Two wave packets of second harmonic poloidal Pc 4 waves with a wave frequency of ~7 mHz were detected by Van Allen Probe A at a radial distance of ~5.8 RE and magnetic local time of 13 hr near the magnetic equator, where plasmaspheric refilling was in progress. Proton butterfly distributions with energy dispersions were also measured at the same time; the proton fluxes at 10-30 keV oscillated with the same frequency as the Pc 4 waves. Using the ion sounding technique, we find that the Pc 4 waves propagated eastward with an a ...

Yamamoto, K.; e, Nos\; Keika, K.; Hartley, D.P.; Smith, C.W.; MacDowall, R.J.; Lanzerotti, L.J.; Mitchell, D.G.; Spence, H.E.; Reeves, G.D.; Wygant, J.R.; Bonnell, J.W.; Oimatsu, S.;

YEAR: 2019     DOI: 10.1029/2019JA027158

drift-bounce resonance; Geomagnetic storm; plasmasphere; ring current; substorm; ULF wave; Van Allen Probes

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

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

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

YEAR: 2019     DOI: 10.1029/2019GL082789

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

The Storm-Time Ring Current Response to ICMEs and CIRs Using Van Allen Probe Observations

Using Van Allen Probe observations of the inner magnetosphere during geomagnetic storms driven by interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs), we characterize the impact of these drivers on the storm-time ring current development. Using 25 ICME- and 35 CIR-driven storms, we have determined the ring current pressure development during the prestorm, main, early-recovery, and late-recovery storm phases, as a function of magnetic local time, L shell and ion species (H+, He+, and O+) ov ...

Mouikis, C.; Bingham, S.; Kistler, L.; Farrugia, C.; Spence, H.; Reeves, G.; Gkioulidou, M.; Mitchell, D.; Kletzing, C.;

YEAR: 2019     DOI: 10.1029/2019JA026695

ICME vs CI; R Ion composition; Ring Current Pressure; Storm phases; Van Allen Probes

Comparison of Electron Loss Models in the Inner Magnetosphere During the 2013~St. Patrick\textquoterights Day Geomagnetic Storm

Electrons with energies in the keV range play an important role in the dynamics of the inner magnetosphere. Therefore, accurately modeling electron fluxes in this region is of great interest. However, these calculations constitute a challenging task since the lifetimes of electrons that are available have limitations. In this study, we simulate electron fluxes in the energy range of 20 eV to 100 keV to assess how well different electron loss models can account for the observed electron fluxes during the Geospace Environment ...

Ferradas, C.; Jordanova, V.; Reeves, G.; Larsen, B.;

YEAR: 2019     DOI: 10.1029/2019JA026649

electron lifetime; electron loss; numerical modeling; pitch angle scattering; Van Allen Probes; Weimer electric field model

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

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

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

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

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

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

Quantification of Energetic Electron Precipitation Driven by Plume Whistler Mode Waves, Plasmaspheric Hiss, and Exohiss

Whistler mode waves are important for precipitating energetic electrons into Earth\textquoterights upper atmosphere, while the quantitative effect of each type of whistler mode wave on electron precipitation is not well understood. In this letter, we evaluate energetic electron precipitation driven by three types of whistler mode waves: plume whistler mode waves, plasmaspheric hiss, and exohiss observed outside the plasmapause. By quantitatively analyzing three conjunction events between Van Allen Probes and POES/MetOp satel ...

Li, W.; Shen, X.-C.; Ma, Q.; Capannolo, L.; Shi, R.; Redmon, R.; Rodriguez, J.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2019     DOI: 10.1029/2019GL082095

electron precipitation; hiss; plasmaspheric plume; Plume wave; Van Allen Probes; whistler mode wave

PreMevE: New Predictive Model for Megaelectron-volt Electrons inside Earth\textquoterights Outer Radiation Belt

This work designs a new model called PreMevE to predict storm-time distributions of relativistic electrons within Earth\textquoterights outer radiation belt. This model takes advantage of the cross-energy, -L-shell, and \textendashpitch-angle coherence associated with wave-electron resonant interactions, ingests observations from belt boundaries\textemdashmainly by NOAA POES in low-Earth-orbits (LEOs), and provides high-fidelity nowcast (multiple-hour prediction) and forecast (> ~1 day) of MeV electron fluxes over L-shells b ...

Chen, Yue; Reeves, Geoffrey; Fu, Xiangrong; Henderson, Michael;

YEAR: 2019     DOI: 10.1029/2018SW002095

event-specific predictions; LANL GEO observations; linear predictive filters; MeV electron events; outer radiation belt; precipitation at low-earth-orbits (LEO); Van Allen Probes

Properties of Whistler Mode Waves in Earth\textquoterights Plasmasphere and Plumes

Whistler mode wave properties inside the plasmasphere and plumes are systematically investigated using 5-year data from Van Allen Probes. The occurrence and intensity of whistler mode waves in the plasmasphere and plumes exhibit dependences on magnetic local time, L, and AE. Based on the dependence of the wave normal angle and Poynting flux direction on L shell and normalized wave frequency to electron cyclotron frequency (fce), whistler mode waves are categorized into four types. Type I: ~0.5 fce with oblique wave normal an ...

Shi, Run; Li, Wen; Ma, Qianli; Green, Alex; Kletzing, Craig; Kurth, William; Hospodarsky, George; Claudepierre, Seth; Spence, Harlan; Reeves, Geoff;

YEAR: 2019     DOI: 10.1029/2018JA026041

Plasmaspheric Hiss; plasmaspheric plume; Van Allen Probes; whistler mode waves

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

A Revised Look at Relativistic Electrons in the Earth\textquoterights Inner Radiation Zone and Slot Region

We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we ...

Claudepierre, S.; O\textquoterightBrien, T.; Looper, M.; Blake, J.; Fennell, J.; Roeder, J.; Clemmons, J.; Mazur, J.; Turner, D.; Reeves, G.; Spence, H.;

YEAR: 2019     DOI: 10.1029/2018JA026349

Inner zone; particle detectors; Radiation belt; relativistic electrons; Slot region; Space weather; Van Allen Probes

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

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

Energisation of the ring current by substorms

The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energisation processes provides valuable insight into how substorm - ring current coupling may contribute to the generation of storm conditions and provide a sou ...

Sandhu, J.; Rae, I.; Freeman, M.; Forsyth, C.; Gkioulidou, M.; Reeves, G.; Spence, H.; Jackman, C.; Lam, M.;

YEAR: 2018     DOI: 10.1029/2018JA025766

BSPICE; HOPE; Magnetosphere; ring current; substorms; Van Allen Probes

MMS, Van Allen Probes, GOES 13, and Ground Based Magnetometer Observations of EMIC Wave Events Before, During, and After a Modest Interplanetary Shock

The stimulation of EMIC waves by a magnetospheric compression is perhaps the closest thing to a controlled experiment that is currently possible in magnetospheric physics, in that one prominent factor that can increase wave growth acts at a well-defined time. We present a detailed analysis of EMIC waves observed in the outer dayside magnetosphere by the four Magnetosphere Multiscale (MMS) spacecraft, Van Allen Probe A, and GOES 13, and by four very high latitude ground magnetometer stations in the western hemisphere before, ...

Engebretson, M.; Posch, J.; Capman, N.; Campuzano, N.; elik, P.; Allen, R.; Vines, S.; Anderson, B.; Tian, S.; Cattell, C.; Wygant, J.; Fuselier, S.; Argall, M.; Lessard, M.; Torbert, R.; Moldwin, M.; Hartinger, M.; Kim, H.; Russell, C.; Kletzing, C.; Reeves, G.; Singer, H.;

YEAR: 2018     DOI: 10.1029/2018JA025984

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

The composition of plasma inside geostationary orbit based on Van Allen Probes observations

The composition of the inner magnetosphere is of great importance for determining the plasma pressure, and thus the currents and magnetic field configuration. In this study, we perform a statistical survey of equatorial plasma pressure distributions and investigate the relative contributions of ions and electron with different energies inside of geostationary orbit under two AE levels based on over sixty months of observations from the HOPE and RBSPICE mass spectrometers on board Van Allen Probes. We find that the total and ...

Yue, Chao; Bortnik, Jacob; Li, Wen; Ma, Qianli; Gkioulidou, Matina; Reeves, Geoffrey; Wang, Chih-Ping; Thorne, Richard; T. Y. Lui, Anthony; Gerrard, Andrew; Spence, Harlan; Mitchell, Donald;

YEAR: 2018     DOI: 10.1029/2018JA025344

ion composition; plasma pressure; Plasmapause; Van Allen Probes

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



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