Bibliography



Found 189 entries in the Bibliography.


Showing entries from 1 through 50


2020

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

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

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

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

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

Effects of a Realistic O + Source on Modeling the Ring Current

We use the UNH-IMEF electric field model to simulate the convection of O+ from the near-earth plasma sheet into the ring current during the March 17, 2015 storm. Using Van Allen Probes data from the night side apogee, we reconstruct a realistic O+ source. Modeling this storm using the UNH-IMEF electric field and a dipole magnetic field has previously been found to have good agreement. Using the realistic source along with drift times and charge exchange loss from these results, we model an inbound pass near the peak of the s ...

Menz, A.M.; Kistler, L.M.; Mouikis, C.G.; Spence, H.E.; Henderson, M.G.;

YEAR: 2019     DOI: 10.1029/2019JA026859

Van Allen Probes

Cold Plasmaspheric Electrons Affected by ULF Waves in the Inner Magnetosphere: A Van Allen Probes Statistical Study

Six years of Van Allen Probes data are used to investigate cold plasmaspheric electrons affected by ultralow-frequency (ULF) waves in the inner magnetosphere (L<7) including spatial distributions, occurrence conditions, and resonant energy range. Events exhibit a global distribution within L= 4\textendash7 but preferentially occur at L\~5.5\textendash7 in the dayside, while there is higher occurrence rate in the duskside than dawnside. They can occur under different geomagnetic activities and solar wind velocities (VS), but ...

Ren, Jie; Zong, Q.; Zhou, X.; Spence, H.; Funsten, H.; Wygant, J.; Rankin, R.;

YEAR: 2019     DOI: 10.1029/2019JA027009

Cold plasmaspheric electrons; drift-bounce resonance; ULF waves; Van Allen Probes; Wave-particle interaction

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

Efficacy of Electric Field Models in Reproducing Observed Ring Current Ion Spectra During Two Geomagnetic Storms

We use the UNH-IMEF, Weimer 1996, https://doi.org/10.1029/96GL02255 and Volland-Stern electric field models along with a dipole magnetic field to calculate drift paths for particles that reach the Van Allen Probes\textquoteright orbit for two inbound passes during two large geomagnetic storms. We compare the particle access in the models with the observed particle access using both realistic and enhanced solar wind model parameters. To test the accuracy of the drift paths, we estimate the H+ charge exchange loss along these ...

Menz, A.M.; Kistler, L.M.; Mouikis, C.G.; Matsui, H.; Spence, H.E.; Thaller, S.A.; Wygant, J.R.;

YEAR: 2019     DOI: 10.1029/2019JA026683

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

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

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

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

YEAR: 2019     DOI: 10.1029/2019JA026477

Van Allen Probes

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

Reply to \textquoterightThe dynamics of Van Allen belts revisited\textquoteright

Mann, I.; Ozeke, L.; Morley, S.; Murphy, K.; Claudepierre, S.; Turner, D.; Baker, D.; Rae, I.; Kale, A.; Milling, D.; Boyd, A.; Spence, H.; Singer, H.; Dimitrakoudis, S.; Daglis, I.; Honary, F.;

YEAR: 2019     DOI: 10.1038/nphys4351

Van Allen Probes

Low-Energy (+ Ion Outflow Directly Into the Inner Magnetosphere: Van Allen Probes Observations

The heavy ion component of the low-energy (eV to hundreds of eV) ion population in the inner magnetosphere, also known as the O+ torus, is a crucial population for various aspects of magnetospheric dynamics. Yet even though its existence has been known since the 1980s, its formation remains an open question. We present a comprehensive study of a low-energy (

Gkioulidou, Matina; Ohtani, S.; . Y. Ukhorskiy, A; Mitchell, D.; Takahashi, K.; Spence, H.; Wygant, J.; Kletzing, C.; Barnes, R.;

YEAR: 2019     DOI: 10.1029/2018JA025862

inner magnetosphere; O+ outflow; Van Allen Probes

The March 2015 Superstorm Revisited: Phase Space Density Profiles and Fast ULF Wave Diffusive Transport

We present the temporal evolution of electron Phase Space Density (PSD) in the outer radiation belt during the intense March 2015 geomagnetic storm. Comparing observed PSD profiles as a function of L* at fixed first, M, and second, K, adiabatic invariants with those produced by simulations is critical for determining the physical processes responsible for the outer radiation belt dynamics. Here we show that the bulk of the accelerated and enhanced outer radiation belt population consists of electrons with K < 0.17 G1/2Re. Fo ...

Ozeke, L.; Mann, I.; Claudepierre, S.; Henderson, M.; Morley, S.; Murphy, K.; Olifer, L.; Spence, H.; Baker, D.;

YEAR: 2019     DOI: 10.1029/2018JA026326

Local Acceleration; March 2015 storm; Phase space density; radial diffusion; Radiation belt; ULF waves; 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

A Statistical Study of EMIC Waves Associated With and Without Energetic Particle Injection From the Magnetotail

To understand the relationship between generation of electromagnetic ion cyclotron (EMIC) waves and energetic particle injections, we performed a statistical study of EMIC waves associated with and without injections based on the Van Allen Probes (Radiation Belt Storm Probes) and Geostationary Operational Environmental Satellite (GOES; GOES-13 and GOES-15) observations. Using 47 months of observations, we identified wave events seen by the Van Allen Probes relative to the plasmapause and to energetic particle injections seen ...

Jun, C.-W.; Yue, C.; Bortnik, J.; Lyons, L.; Nishimura, Y.; Kletzing, C.; Wygant, J.; Spence, H.;

YEAR: 2019     DOI: 10.1029/2018JA025886

EMIC waves associated with and without injections; Relationship between EMIC wave activity and energetic H+ flux variation; Simultaneous observations using the Van Allen Probes and GOES satellites; Spatial occurrence distributions of EMIC waves; Van Allen Probes

2018

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

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

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

Magnetospheric source region of auroral finger-like structures observed by the RBSP-A satellite

Auroral finger-like structures appear equatorward of the auroral oval in the diffuse auroral region and contribute to the auroral fragmentation into patches. A previous report of the first conjugate observation of auroral finger-like structures using a THEMIS GBO camera and the THEMIS-E satellite at a radial distance of \~8 RE showed anti-phase oscillations of magnetic and plasma pressures in the dawnside plasma sheet. In the present study, we report another simultaneous observation of auroral finger-like structures at Gilla ...

Nishi, Katsuki; Shiokawa, Kazuo; Spence, Harlan;

YEAR: 2018     DOI: 10.1029/2018JA025480

Auroral finger-like structure; inner magnetosphere; pressure-driven instability; 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

EMIC wave events during the four GEM QARBM challenge intervals

This paper presents observations of EMIC waves from multiple data sources during the four GEM challenge events in 2013 selected by the GEM \textquotedblleftQuantitative Assessment of Radiation Belt Modeling\textquotedblright focus group: March 17-18 (Stormtime Enhancement), May 31-June 2 (Stormtime Dropout), September 19-20 (Non-storm Enhancement), and September 23-25 (Non-storm Dropout). Observations include EMIC wave data from the Van Allen Probes, GOES, and THEMIS spacecraft in the near-equatorial magnetosphere and from s ...

Engebretson, M.; Posch, J.; Braun, D.; Li, W.; Ma, Q.; Kellerman, A.; Huang, C.-L.; Kanekal, S.; Kletzing, C.; Wygant, J.; Spence, H.; Baker, D.; Fennell, J.; Angelopoulos, V.; Singer, H.; Lessard, M.; Horne, R.; Raita, T.; Shiokawa, K.; Rakhmatulin, R.; Dmitriev, E.; Ermakova, E.;

YEAR: 2018     DOI: 10.1029/2018JA025505

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

A comparative study of ULF waves\textquoteright role in the dynamics of charged particles in the plasmasphere: Van Allen Probes observation

By analyzing observations from Van Allen Probes in its inbound and outbound orbits, we present evidence of coherent enhancement of cold plasmaspheric electrons and ions due to drift-bounce resonance with ULF waves. From 18:00 UT on 28 May 2017 to 10:00 UT on 29 May 2017, newly formed poloidal mode standing ULF waves with significant electric field oscillations were observed in two consecutive orbits when Probe B was travelling inbound. In contrast to observations during outbound orbits, the cold (< 150 eV) electorns measured ...

Ren, Jie; Zong, Qiu-Gang; Miyoshi, Yoshizumi; Rankin, Robert; Spence, Harlan; Funsten, Herbert; Wygant, John; Kletzing, Craig;

YEAR: 2018     DOI: 10.1029/2018JA025255

Cold plasmaspheric electrons acceleration; Drfit-bounce resonance; Modification of electron and ion density profile; Substorm activities; ULF waves; Van Allen Probes

Plasma anisotropies and currents in the near-Earth plasma sheet and inner magnetosphere

The region occupying radial distances of \~3 - 9 Earth radii (RE) in the night side, includes the near-Earth plasma sheet with stretched magnetic field lines and the inner magnetosphere with strong dipolar magnetic field. In this region, the plasma flow energy, which was injected into the inner magnetosphere from the magnetotail, is converted to particle heating and electromagnetic wave generation. These important processes are controlled by plasma anisotropies, which are the focus of this study. Using measurements of THEMIS ...

Artemyev, A.; Zhang, X.-J.; Angelopoulos, V.; Runov, A.; Spence, H.; Larsen, B.;

YEAR: 2018     DOI: 10.1029/2018JA025232

injections; inner magnetosphere; plasma currents; plasma sheet; Van Allen Probes

Rapid Enhancements of the Seed Populations in the Heart of the Earth\textquoterights Outer Radiation Belt: A Multicase Study

To better understand rapid enhancements of the seed populations (hundreds of keV electrons) in the heart of the Earth\textquoterights outer radiation belt (L* ~ 3.5\textendash5.0) during different geomagnetic activities, we investigate three enhancement events measured by Van Allen Probes in detail. Observations of the fluxes and the pitch angle distributions of energetic electrons are analyzed to determine rapid enhancements of the seed populations. Our study shows that three specified processes associated with substorm ele ...

Tang, C.; Xie, X.; Ni, B.; Su, Z.; Reeves, G.; Zhang, J.-C.; Baker, D.; Spence, H.; Funsten, H.; Blake, J.; Wygant, J.; . Y. Dai, G;

YEAR: 2018     DOI: 10.1029/2017JA025142

enhanced convection; Substorm Injections; the outer radiation belt; the seed population; ULF waves; Van Allen Probes

Response of Different Ion Species to Local Magnetic Dipolarization Inside Geosynchronous Orbit

This paper examines how hydrogen, helium and oxygen (H, He and O) ion fluxes at 1\textendash1000 keV typically respond to local magnetic dipolarization inside geosynchronous orbit (GEO). We extracted 144 dipolarizations which occurred at magnetic inclination > 30\textdegree from the 2012\textendash2016 tail seasons\textquoteright observations of the Van Allen Probes spacecraft and then defined typical flux changes of these ion species by performing a superposed epoch analysis. On average, the dipolarization inside GEO is acc ...

Motoba, T.; Ohtani, S.; Gkioulidou, M.; Ukhorskiy, A.; Mitchell, D.; Takahashi, K.; Lanzerotti, L.; Kletzing, C.; Spence, H.; Wygant, J.;

YEAR: 2018     DOI: 10.1029/2018JA025557

deep inside geosynchronous orbit; dipolarizations; Ion injections; ion species; Van Allen Probes

What Causes Radiation Belt Enhancements: A Survey of the Van Allen Probes Era

We survey radiation belt enhancement events during the Van Allen Probes era to determine what mechanism is the dominant cause of enhancements and where it is most effective. Two primary mechanisms have been proposed: (1) betatron/Fermi acceleration due to the Earthward radial transport of electrons which produces monotonic gradients in phase space density (PSD) and (2) \textquotedblleftlocal acceleration" due to gyro/Landau resonant interaction with electromagnetic waves which produces radially localized, growing peaks in PS ...

Boyd, A.J.; Turner, D.L.; Reeves, G.D.; Spence, H.E.; Baker, D.N.; Blake, J.B.;

YEAR: 2018     DOI: 10.1029/2018GL077699

Local Acceleration; Phase space density; Radiation belt; THEMIS; Van Allen Probes

An empirical model of radiation belt electron pitch angle distributions based on Van Allen Probes measurements

Based on over 4 years of Van Allen Probes measurements, an empirical model of radiation belt electron equatorial pitch angle distribution (PAD) is constructed. The model, developed by fitting electron PADs with Legendre polynomials, provides the statistical PADs as a function of L-shell (L=1 \textendash 6), magnetic local time (MLT), electron energy (~30 keV \textendash 5.2 MeV), and geomagnetic activity (represented by the Dst index), and is also the first empirical PAD model in the inner belt and slot region. For MeV elect ...

Zhao, H.; Friedel, R.; Chen, Y.; Reeves, G.; Baker, D.; Li, X.; Jaynes, A.; Kanekal, S.; Claudepierre, S.; Fennell, J.; Blake, J.; Spence, H.;

YEAR: 2018     DOI: 10.1029/2018JA025277

Empirical Model; Geomagnetic storms; inner belt and slot region; Pitch angle distribution; radiation belt electrons; 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

Quantitative Evaluation of Radial Diffusion and Local Acceleration Processes During GEM Challenge Events

We simulate the radiation belt electron flux enhancements during selected Geospace Environment Modeling (GEM) challenge events to quantitatively compare the major processes involved in relativistic electron acceleration under different conditions. Van Allen Probes observed significant electron flux enhancement during both the storm time of 17\textendash18 March 2013 and non\textendashstorm time of 19\textendash20 September 2013, but the distributions of plasma waves and energetic electrons for the two events were dramaticall ...

Ma, Q.; Li, W.; Bortnik, J.; Thorne, R.; Chu, X.; Ozeke, L.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Engebretson, M.; Spence, H.; Baker, D.; Blake, J.; Fennell, J.; Claudepierre, S.;

YEAR: 2018     DOI: 10.1002/2017JA025114

electron accelerationl whistler mode waves; radial diffusion; radiation belt simulation; Van Allen Probes; Van Allen Probes observation

Comparing simulated and observed EMIC wave amplitudes using in situ Van Allen Probes\textquoteright measurements

We perform a statistical study calculating electromagnetic ion cyclotron (EMIC) wave amplitudes based off in situ plasma measurements taken by the Van Allen Probes\textquoteright (1.1\textendash5.8 Re) Helium, Oxygen, Proton, Electron (HOPE) instrument. Calculated wave amplitudes are compared to EMIC waves observed by the Electric and Magnetic Field Instrument Suite and Integrated Science on board the Van Allen Probes during the same period. The survey covers a 22-month period (1 November 2012 to 31 August 2014), a full Van ...

Saikin, A.A.; Jordanova, V.K.; Zhang, J.C.; Smith, C.W.; Spence, H.E.; Larsen, B.A.; Reeves, G.D.; Torbert, R.B.; Kletzing, C.A.; Zhelavskaya, I.S.; Shprits, Y.Y.;

YEAR: 2018     DOI: 10.1016/j.jastp.2018.01.024

EMIC waves Van Allen Probes Linear theory Wave generation; Van Allen Probes

2017

Temporal evolution of ion spectral structures during a geomagnetic storm: Observations and modeling

Using the Van Allen Probes/Helium, Oxygen, Proton, and Electron (HOPE) mass spectrometer, we perform a case study of the temporal evolution of ion spectral structures observed in the energy range of 1-~50 keV throughout the geomagnetic storm of 2 October 2013. The ion spectral features are observed near the inner edge of the plasma sheet and are signatures of fresh transport from the plasma sheet into the inner magnetosphere. We find that the characteristics of the ion structures are determined by the intensity of the convec ...

Ferradas, C.; Zhang, J.-C.; Spence, H.; Kistler, L.; Larsen, B.; Reeves, G.; Skoug, R.; Funsten, H.;

YEAR: 2017     DOI: 10.1002/2017JA024702

Geomagnetic storm; ion injection; ion nose structure; numerical modeling; Van Allen Probes; Weimer electric field model

Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping

Satellite observations of a significant population of very oblique chorus waves in the outer radiation belt have fueled considerable interest in the effects of these waves on energetic electron scattering and acceleration. However, corresponding diffusion rates are extremely sensitive to the refractive index N, controlled by hot plasma effects including Landau damping and wave dispersion modifications by suprathermal (15\textendash100 eV) electrons. A combined investigation of wave and electron distribution characteristics o ...

Ma, Q.; Artemyev, A.; Mourenas, D.; Li, W.; Thorne, R.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Reeves, G.; Spence, H.; Wygant, J.;

YEAR: 2017     DOI: 10.1002/2017GL075892

Landau damping; maximum refractive index; oblique chorus waves; thermal electron effects; Van Allen Probes; Van Allen Probes observation

Chorus Wave Modulation of Langmuir Waves in the Radiation Belts

Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E|| component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity tha ...

Li, Jinxing; Bortnik, Jacob; An, Xin; Li, Wen; Thorne, Richard; Zhou, Meng; Kurth, William; Hospodarsky, George; Funsten, Herbert; Spence, Harlan;

YEAR: 2017     DOI: 10.1002/2017GL075877

Chorus wave; Landau resonance; Langmuir wave; nonlinear interaction; Radiation belt; Van Allen Probes; wave modulation

Observations Directly Linking Relativistic Electron Microbursts to Whistler Mode Chorus: Van Allen Probes and FIREBIRD II

We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus ...

Breneman, A.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D.; Santolik, O.; Wygant, J.; Cattell, C.; Thaller, S.; Blake, B.; Spence, H.; Kletzing, C.;

YEAR: 2017     DOI: 10.1002/2017GL075001

Chorus; conjunction; FIREBIRD; microburst; Van Allen Probes

Van Allen Probes measurements of energetic particle deep penetration into the low L region (L<4) during the storm on 8 April 2016

Using measurements from the Van Allen Probes, a penetration event of 10s \textendash 100s of keV electrons and 10s of keV protons into the low L-shells (L<4) is studied. Timing and magnetic local time (MLT) differences of energetic particle deep penetration are unveiled and underlying physical processes are examined. During this event, both proton and electron penetrations are MLT-asymmetric. The observed MLT difference of proton penetration is consistent with convection of plasma sheet protons, suggesting enhanced convectio ...

Zhao, H.; Baker, D.; Califf, S.; Li, X.; Jaynes, A.; Leonard, T.; Kanekal, S.; Blake, J.; Fennell, J.; Claudepierre, S.; Turner, D.; Reeves, G.; Spence, H.;

YEAR: 2017     DOI: 10.1002/2017JA024558

The Evolution of the Plasma Sheet Ion Composition: Storms and Recoveries

The ion plasma sheet (~few hundred eV to ~few 10s keV) is usually dominated by H+ ions. Here, changes in ion composition within the plasma sheet are explored both during individual events, and statistically during 54 calm-to-storm events and during 21 active-to-calm events. Ion composition data from the HOPE (Helium, Oxygen, Proton, Electron) instruments onboard Van Allen Probes satellites provide exceptional spatial and temporal resolution of the H+, O+, and He+ ion fluxes in the plasma sheet. H+ shown to be the dominant io ...

Denton, M.; Thomsen, M.; Reeves, G.; Larsen, B.; Henderson, M.; Jordanova, V.; Fernandes, P.; Friedel, R.; Skoug, R.; Funsten, H.; MacDonald, E.; Spence, H.;

YEAR: 2017     DOI: 10.1002/2017JA024475

plasma sheet; Van Allen Probes

Relativistic electron increase during chorus wave activities on the 6-8 March 2016 geomagnetic storm

There was a geomagnetic storm on 6\textendash8 March 2016, in which Van Allen Probes A and B separated by \~2.5 h measured increase of relativistic electrons with energies \~ several hundred keV to 1 MeV. Simultaneously, chorus waves were measured by both Van Allen Probes and Magnetospheric Multiscale (MMS) mission. Some of the chorus elements were rising-tones, possibly due to nonlinear effects. These measurements are compared with a nonlinear theory of chorus waves incorporating the inhomogeneity ratio and the field equati ...

Matsui, H.; Torbert, R.; Spence, H.; Argall, M.; Alm, L.; Farrugia, C.; Kurth, W.; Baker, D.; Blake, J.; Funsten, H.; Reeves, G.; Ergun, R.; Khotyaintsev, Yu.; Lindqvist, P.-A.;

YEAR: 2017     DOI: 10.1002/2017JA024540

chorus waves; Geomagnetic storm; relativistic electrons; Van Allen Probes

Multipoint observations of energetic particle injections and substorm activity during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes

This study examines multipoint observations during a conjunction between MMS and Van Allen Probes on 07 April 2016 in which a series of energetic particle injections occurred. With complementary data from THEMIS, Geotail, and LANL-GEO (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (max. AE < 300 nT) during quiet geomagnetic conditions in steady, below-average solar wind, a complex serie ...

Turner, D.; Fennell, J.; Blake, J.; Claudepierre, S.; Clemmons, J.; Jaynes, A.; Leonard, T.; Baker, D.; Cohen, I.; Gkioulidou, M.; . Y. Ukhorskiy, A; Mauk, B.; Gabrielse, C.; Angelopoulos, V.; Strangeway, R.; Kletzing, C.; Le Contel, O.; Spence, H.; Torbert, R.; Burch, J.; Reeves, G.;

YEAR: 2017     DOI: 10.1002/2017JA024554

energetic particles; injections; inner magnetosphere; plasma sheet; substorms; Van Allen Probes; wave-particle interactions

The Warm Plasma Composition in the Inner Magnetosphere during 2012-2015

Ionospheric heavy ions play an important role in the dynamics of Earth\textquoterights magnetosphere. The greater mass and gyro radius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during geomagnetic storms. At sub-keV energies, multi-species ion populations in the inner magnetosphere form the warm plasma cloak, occupying the energy range between the ...

Jahn, J.-M.; Goldstein, J.; Reeves, G.; Fernandes, P.; Skoug, R.; Larsen, B.; Spence, H.;

YEAR: 2017     DOI: 10.1002/2017JA024183

geomagnetic activity; inner magnetosphere; plasma composition; plasma density; statistics; Van Allen Probes

The characteristic response of whistler mode waves to interplanetary shocks

Magnetospheric whistler mode waves play a key role in regulating the dynamics of the electron radiation belts. Recent satellite observations indicate a significant influence of interplanetary (IP) shocks on whistler mode wave power in the inner magnetosphere. In this study, we statistically investigate the response of whistler mode chorus and plasmaspheric hiss to IP shocks based on Van Allen Probes and THEMIS satellite observations. Immediately after the IP shock arrival, chorus wave power is usually intensified, often at p ...

Yue, Chao; Chen, Lunjin; Bortnik, Jacob; Ma, Qianli; Thorne, Richard; Angelopoulos, Vassilis; Li, Jinxing; An, Xin; Zhou, Chen; Kletzing, Craig; Reeves, Geoffrey; Spence, Harlan;

YEAR: 2017     DOI: 10.1002/2017JA024574

IP shocks; MLT dependent; Plasmaspheric Hiss; Ray Tracing; Van Allen Probes; whistler mode chorus



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