Found 938 entries in the Bibliography.

Showing entries from 451 through 500


Multispacecraft Observations and Modeling of the June 22/23, 2015 Geomagnetic Storm

The magnetic storm of June 22-23, 2015 was one of the largest in the current solar cycle. We present in situ observations from the Magnetospheric Multiscale Mission (MMS) and the Van Allen Probes (VAP) in the magnetotail, field-aligned currents from AMPERE, and ionospheric flow data from DMSP. Our real-time space weather alert system sent out a \textquotedblleftred alert\textquotedblright, correctly predicting Kp indices greater than 8. We show strong outflow of ionospheric Oxygen, dipolarizations in the MMS magnetometer dat ...

Reiff, P.; Daou, A.; . Y. Sazykin, S; Nakamura, R.; Hairston, M.; Coffey, V.; Chandler, M.; Anderson, B.; Russell, C.; Welling, D.; Fuselier, S.; Genestreti, K.;

YEAR: 2016     DOI: 10.1002/2016GL069154

Dipolarization; Geomagnetic storm; MMS; prediction; simulation; Space weather; Van Allen Probes

New Chorus Wave Properties Near the Equator from Van Allen Probes Wave Observations

The chorus wave properties are evaluated using Van Allen Probes data in the Earth\textquoterights equatorial magnetosphere. Two distinct modes of lower band chorus are identified: a quasi-parallel mode and a quasi-electrostatic mode, whose wave normal direction is close to the resonance cone. Statistical results indicate that the quasi-electrostatic (quasi-parallel) mode preferentially occurs during relatively quiet (disturbed) geomagnetic activity at lower (higher) L shells. Although the magnetic intensity of the quasi-elec ...

Li, W.; Santolik, O.; Bortnik, J.; Thorne, R.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

YEAR: 2016     DOI: 10.1002/2016GL068780

Chorus wave; oblique; quasi-electrostatic; quasi-parallel; Van Allen Probes; wave normal angles

O + Ion Conic and Plasma Sheet Dynamics Observed by Van Allen Probe Satellites during the 1 June 2013 Magnetic Storm

The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm\textquoterights main phase. About an hour after crossing the ring current\textquoterights \textquotedblleftnose structure\textquotedblright into the plasma sheet, the satellites encountered a quasi-periodic sequence of 0.08 - 3 keV O+ ions. Pitch angle distributions of this population consistently peaked nearly anti-parallel to the local magnetic field. We interpret this population as O+ conics originat ...

Burke, W.; Erickson, P.; Yang, J.; Foster, J.; Wygant, J.; Reeves, G.; Kletzing, C.;

YEAR: 2016     DOI: 10.1002/2015JA021795

oxygen ion conics; plasma sheet dynamics; Van Allen Probes

Occurrence Characteristics of Outer Zone Relativistic Electron Butterfly Distribution: A Survey of Van Allen Probes REPT Measurements

Using Van Allen Probes REPT pitch angle resolved electron flux data from September 2012 to March 2015, we investigate in detail the global occurrence pattern of equatorial (|λ| <= 3\textdegree) butterfly distribution of outer zone relativistic electrons and its potential correlation with the solar wind dynamic pressure. The statistical results demonstrate that these butterfly distributions occur with the highest occurrence rate ~ 80\% at ~ 20 \textendash 04 MLT and L > ~ 5.5 and with the second peak (> ~ 50 \%) at ~ 11 \tex ...

Ni, Binbin; Zou, Zhengyang; Li, Xinlin; Bortnik, Jacob; Xie, Lun; Gu, Xudong;

YEAR: 2016     DOI: 10.1002/2016GL069350

butterfly pitch angle distributions; global occurrence pattern; outer radiation belt; relativistic electrons; Van Allen Probes

Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

We present dynamic simulations of energy-dependent losses in the radiation belt " slot region" and the formation of the two-belt structure for the quiet days after the March 1st storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally-resolved whistler mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L-shells (2 to 6) including (a) the strong energy-dependence to t ...

Ripoll, J.; Reeves, G.; Cunningham, G.; Loridan, V.; Denton, M.; ik, O.; Kurth, W.; Kletzing, C.; Turner, D.; Henderson, M.; . Y. Ukhorskiy, A;

YEAR: 2016     DOI: 10.1002/2016GL068869

electron lifetimes; electron losses; hiss waves; Radiation belts; Slot region; Van Allen Probes; wave particle interactions

Simulation of energy-dependent electron diffusion processes in the Earth\textquoterights outer radiation belt

The radial and local diffusion processes induced by various plasma waves govern the highly energetic electron dynamics in the Earth\textquoterights radiation belts, causing distinct characteristics in electron distributions at various energies. In this study, we present our simulation results of the energetic electron evolution during a geomagnetic storm using the University of California, Los Angeles 3-D diffusion code. Following the plasma sheet electron injections, the electrons at different energy bands detected by the M ...

Ma, Q.; Li, W.; Thorne, R.; Nishimura, Y.; Zhang, X.-J.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Henderson, M.; Spence, H.; Baker, D.; Blake, J.; Fennell, J.; Angelopoulos, V.;

YEAR: 2016     DOI: 10.1002/2016JA022507

electron acceleration and loss; energy-dependent diffusion; radial diffusion; radiation belt simulation; Van Allen Probes

A statistical study of proton pitch angle distributions measured by the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

A statistical study of ring current-energy proton pitch angle distributions (PADs) in Earth\textquoterights inner magnetosphere is reported here. The data are from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the Van Allen Probe B spacecraft from January 1, 2013 to April 15, 2015. By fitting the data to the functional form sinnα, where α is the proton pitch angle, we examine proton PADs at the energies 50, 100, 180, 328 and 488 keV in the L-shell range from L = 2.5 to L = 6. Three PAD types ...

Shi, Run; Summers, Danny; Ni, Binbin; Manweiler, Jerry; Mitchell, Donald; Lanzerotti, Louis;

YEAR: 2016     DOI: 10.1002/2015JA022140

proton pitch angle distributions; Van Allen Probes

Storm-time dynamics of ring current protons: Implications for the long-term energy budget in the inner magnetosphere

Our investigation of the long-term ring current proton pressure evolution in Earth\textquoterights inner magnetosphere based on Van Allen Probes data shows drastically different behavior of the low- and high- energy components of the ring current proton population with respect to theSYM-H index variation. We found that while the low-energy component of the protons (<80 keV) is strongly governed by convective timescales and is very well correlated with the absolute value of SYM-H index, the high-energy component (>100 keV) va ...

Gkioulidou, Matina; Ukhorskiy, A.; Mitchell, D.; Lanzerotti, L.;

YEAR: 2016     DOI: 10.1002/2016GL068013

energy budget; Geomagnetic storms; inner magnetosphere; ring current; Van Allen Probes

Structure and Evolution of Electron "Zebra Stripes" in the Inner Radiation Belt

Zebra stripes\textquotedblright are newly found energetic electron energy-spatial (L shell) distributed structure with an energy between tens to a few hundreds keV in the inner radiation belt. Using high-quality measurements of electron fluxes from Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on board the twin Van Allen Probes, we carry out case and statistical studies from April 2013 to April 2014 to study the structural and evolutionary characteristics of zebra stripes below L = 3. It is revealed that t ...

Liu, Y.; Zong, Q.-G.; Zhou, X.-Z.; Foster, J.; Rankin, R.;

YEAR: 2016     DOI: 10.1002/2015JA022077

electric field; energetic electrons; particle dynamic; Radiation belt; Van Allen Probes; zebra stripes

Things we don\textquoterightt yet understand about solar driving of the radiation belts.

This commentary explores how close we are to predicting the behavior of the radiations belts - the primary science objective of NASA\textquoterights Van Allen Probes mission. Starting with what we know or think we know about competing sources, enhancement, transport, and loss, I walk through recent papers that have improved our understanding and then focus on flux dropouts as one particular yardstick of success. I mention a new paradigm for electrons and the importance of reliably matching models and observations for differe ...

Kessel, Mona;

YEAR: 2016     DOI: 10.1002/2016JA022472

Radiation belt; Van Allen Probes

Using the cold plasma dispersion relation and whistler-mode waves to quantify the antenna sheath impedance of the Van Allen Probes EFW instrument

Cold plasma theory and parallel wave propagation are often assumed when approximating the whistler mode magnetic field wave power from electric field observations. The current study is the first to include the wave normal angle from the Electric and Magnetic Field Instrument Suite and Integrated Science package on board the Van Allen Probes in the conversion factor, thus allowing for the accuracy of these assumptions to be quantified. Results indicate that removing the assumption of parallel propagation does not significantl ...

Hartley, D.; Kletzing, C.; Kurth, W.; Bounds, S.; Averkamp, T.; Hospodarsky, G.; Wygant, J.; Bonnell, J.; ik, O.; Watt, C.;

YEAR: 2016     DOI: 10.1002/2016JA022501

EFW; EMFISIS; Plasmaspheric Hiss; sheath impedance; Van Allen Probes; whistler mode chorus

BARREL observations of a Solar Energetic Electron and Solar Energetic Proton event

During the second Balloon Array for Radiation Belt Relativistic Electron Losses (BARREL) campaign two solar energetic proton (SEP) events were observed. Although BARREL was designed to observe X-rays created during electron precipitation events, it is sensitive to X-rays from other sources. The gamma lines produced when energetic protons hit the upper atmosphere are used in this paper to study SEP events. During the second SEP event starting on 7 January 2014 and lasting \~ 3 days, which also had a solar energetic electron ( ...

Halford, A.; McGregor, S.; Hudson, M.; Millan, R.; Kress, B.;

YEAR: 2016     DOI: 10.1002/2016JA022462

BARREL; electron precipitation; proton precipitation; Solar Energetic Electrons; Solar Energetic Protons; Solar storm; Van Allen Probes

Electron butterfly distribution modulation by magnetosonic waves

The butterfly pitch angle distribution is observed as a dip in an otherwise normal distribution of electrons centered about αeq=90\textdegree. During storm times, the formation of the butterfly distribution on the nightside magnetosphere has been attributed to L shell splitting combined with magnetopause shadowing and strong positive radial flux gradients. It has been shown that this distribution can be caused by combined chorus and magnetosonic wave scattering where the two waves work together but at different local times. ...

Maldonado, Armando; Chen, Lunjin; Claudepierre, Seth; Bortnik, Jacob; Thorne, Richard; Spence, Harlan;

YEAR: 2016     DOI: 10.1002/2016GL068161

butterfly; electron; magnetosonic; Magnetosphere; Van Allen Probes; wave particle interaction

Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance

Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90\textdegree, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been ...

Li, Jinxing; Ni, Binbin; Ma, Qianli; Xie, Lun; Pu, Zuyin; Fu, Suiyan; Thorne, R.; Bortnik, J.; Chen, Lunjin; Li, Wen; Baker, Daniel; Kletzing, Craig; Kurth, William; Hospodarsky, George; Fennell, Joseph; Reeves, Geoffrey; Spence, Harlan; Funsten, Herbert; Summers, Danny;

YEAR: 2016     DOI: 10.1002/2016GL067853

butterfly distributions; energetic electrons; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

A neural network approach for identifying particle pitch angle distributions in Van Allen Probes data

Analysis of particle pitch angle distributions (PADs) has been used as a means to comprehend a multitude of different physical mechanisms that lead to flux variations in the Van Allen belts and also to particle precipitation into the upper atmosphere. In this work we developed a neural network-based data clustering methodology that automatically identifies distinct PAD types in an unsupervised way using particle flux data. One can promptly identify and locate three well-known PAD types in both time and radial distance, namel ...

Souza, V.; Vieira, L.; Medeiros, C.; Da Silva, L.; Alves, L.; Koga, D.; Sibeck, D.; Walsh, B.; Kanekal, S.; Jauer, P.; Rockenbach, M.; Dal Lago, A.; Silveira, M.; Marchezi, J.; Mendes, O.; Gonzalez, W.; Baker, D.;

YEAR: 2016     DOI: 10.1002/2015SW001349

pitch angle distributions; self-organizing maps; Van Allen belt\textquoterights monitoring; Van Allen Probes

Oblique Whistler-Mode Waves in the Earth\textquoterights Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics

In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth\textquoterights inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and no ...

Artemyev, Anton; Agapitov, Oleksiy; Mourenas, Didier; Krasnoselskikh, Vladimir; Shastun, Vitalii; Mozer, Forrest;

YEAR: 2016     DOI: 10.1007/s11214-016-0252-5

Earth radiation belts; Van Allen Probes; Wave-particle interaction; Whistler waves

Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements

Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; a ...

Zhao, H.; Li, X.; Baker, D.; Claudepierre, S.; Fennell, J.; Blake, J.; Larsen, B.; Skoug, R.; Funsten, H.; Friedel, R.; Reeves, G.; Spence, H.; Mitchell, D.; Lanzerotti, L.;

YEAR: 2016     DOI: 10.1002/2016JA022358

deep injections; Geomagnetic storms; ring current; ring current energy content; ring current electrons; Van Allen Probes

Ultrarelativistic electron butterfly distributions created by parallel acceleration due to magnetosonic waves

The Van Allen Probe observations during the recovery phase of a large storm that occurred on 17 March 2015 showed that the ultrarelativistic electrons at the inner boundary of the outer radiation belt (L* = 2.6\textendash3.7) exhibited butterfly pitch angle distributions, while the inner belt and the slot region also showed evidence of sub-MeV electron butterfly distributions. Strong magnetosonic waves were observed in the same regions and at the same time periods as these butterfly distributions. Moreover, when these magnet ...

Li, Jinxing; Bortnik, Jacob; Thorne, Richard; Li, Wen; Ma, Qianli; Baker, Daniel; Reeves, Geoffrey; Fennell, Joseph; Spence, Harlan; Kletzing, Craig; Kurth, William; Hospodarsky, George; Angelopoulos, Vassilis; Blake, Bernard.;

YEAR: 2016     DOI: 10.1002/2016JA022370

butterfly distributions; Landau resonance; magnetosonic waves; Radiation belt; Van Allen Probes

Charged particle behavior in the growth and damping stages of ultralow frequency waves: theory and Van Allen Probes observations

Ultralow frequency (ULF) electromagnetic waves in Earth\textquoterights magnetosphere can accelerate charged particles via a process called drift resonance. In the conventional drift-resonance theory, a default assumption is that the wave growth rate is time-independent, positive, and extremely small. However, this is not the case for ULF waves in the real magnetosphere. The ULF waves must have experienced an earlier growth stage when their energy was taken from external and/or internal sources, and as time proceeds the wave ...

Zhou, Xu-Zhi; Wang, Zi-Han; Zong, Qiu-Gang; Rankin, Robert; Kivelson, Margaret; Chen, Xing-Ran; Blake, Bernard; Wygant, John; Kletzing, Craig;

YEAR: 2016     DOI: 10.1002/2016JA022447

drift resonance; Radiation belt; ULF waves; Van Allen Probes; wave growth and damping; Wave-particle interaction

Inward diffusion and loss of radiation belt protons

Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at ...

Selesnick, R.; Baker, D.; Jaynes, A.; Li, X.; Kanekal, S.; Hudson, M.; Kress, B.;

YEAR: 2016     DOI: 10.1002/2015JA022154

protons; radial diffusion; Radiation belt; Van Allen Probes

A Statistical Study of Whistler Waves Observed by Van Allen Probes (RBSP) and Lightning Detected by WWLLN

Lightning-generated whistler waves are electromagnetic plasma waves in the very low frequency (VLF) band, which play an important role in the dynamics of radiation belt particles. In this paper, we statistically analyze simultaneous waveform data from the Van Allen Probes (Radiation Belt Storm Probes, RBSP) and global lightning data from the World Wide Lightning Location Network (WWLLN). Data were obtained between July to September 2013 and between March and April 2014. For each day during these periods, we predicted the mos ...

Zheng, Hao; Holzworth, Robert; Brundell, James; Jacobson, Abram; Wygant, John; Hospodarsky, George; Mozer, Forrest; Bonnell, John;

YEAR: 2016     DOI: 10.1002/2015JA022010

lightnting; RBSP; Van Allen Probes; VLF; whistler wave

Storm-time dynamics of ring current protons: Implications for the long-term energy budget in the inner magnetosphere

Our investigation of the long-term ring current proton pressure evolution in Earth\textquoterights inner magnetosphere based on Van Allen Probes data shows drastically different behavior of the low- and high- energy components of the ring current proton population with respect to the Sym-H index variation. We found that while the low-energy component of the protons (<80 keV) is strongly governed by convective timescales and is very well correlated with the absolute value of Sym-H index, the high-energy component (>100 keV) v ...

Gkioulidou, Matina; Ukhorskiy, A.; Mitchell, D.; Lanzerotti, L.;

YEAR: 2016     DOI: 10.1002/2016GL068013

energy budget; Geomagnetic storms; inner magnetosphere; ring current; Van Allen Probes

Experimental evidence of drift compressional waves in the magnetosphere: an Ekaterinburg coherent decameter radar case study

A case study of shortwave radar observations of magnetospheric Pc5 ULF waves (wave periods of 150\textendash600 s) that occurred on 26 December 2014 in the nightside magnetosphere during substorm activity is presented. The radar study of waves in the magnetosphere is based on analysis of scattering from field-aligned irregularities of the ionospheric F layer. Variations of their inline image drift velocity at F layer heights are associated with the wave electric field. Analysis of the observations from the Ekaterinburg (EKB) ...

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

YEAR: 2016     DOI: 10.1002/2015JA022155

kinetic instabilities; ULF waves

Forecasting and remote sensing outer belt relativistic electrons from low Earth orbit

This study demonstrates the feasibility and reliability of using observations from low Earth orbit (LEO) to forecast and nowcast relativistic electrons in the outer radiation belt. We first report a high cross-energy, cross-pitch-angle coherence discovered between the trapped MeV electrons and precipitating approximately hundreds (~100s) of keV electrons\textemdashobserved by satellites with very different altitudes\textemdashwith correlation coefficients as high as ≳ 0.85. Based upon the coherence, we then tested the feas ...

Chen, Yue; Reeves, Geoffrey; Cunningham, Gregory; Redmon, Robert; Henderson, Michael;

YEAR: 2016     DOI: 10.1002/2015GL067481

forecast and nowcast; hundreds of keV precipitating electrons; LEO observations; Radiation belts; relativistic electrons; wave particle interactions

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

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

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

YEAR: 2016     DOI: 10.1002/2015SW001339

Global Positioning System; Van Allen Probes

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

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

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

YEAR: 2016     DOI: 10.1002/2016GL067687

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021878

Global Positioning System; Van Allen Probes

Pulsating proton aurora caused by rising tone Pc1 waves

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

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

YEAR: 2016     DOI: 10.1002/2015JA021681

EMIC-triggered waves; Pc1 waves; proton aurora

Reconstructing the magnetosphere from data using radial basis functions

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

Andreeva, Varvara; Tsyganenko, Nikolai;

YEAR: 2016     DOI: 10.1002/2015JA022242

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

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

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

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

YEAR: 2016     DOI: 10.1002/2016GL068260

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015SW001345

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021844

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

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

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

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

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

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021863

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021691

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

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

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

Pierrard, V.; Rosson, G.;

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

Van Allen Probes

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

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

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

YEAR: 2016     DOI: 10.1002/2015GL067316

Acceleration; Van Allen Probes

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

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

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

YEAR: 2016     DOI: 10.1002/2015JA021772

chorus waves; Geomagnetic storm; nonlinearity; Van Allen Probes

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

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

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

YEAR: 2016     DOI: 10.1002/2014JA020877

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

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

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

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

YEAR: 2016     DOI: 10.1002/2015GL066893

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

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

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

Lejosne, Solène; Roederer, Juan;

YEAR: 2016     DOI: 10.1002/2015JA021925

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


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

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

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

YEAR: 2015     DOI: 10.1002/2015GL066674

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

Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

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

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

YEAR: 2015     DOI: 10.1038/srep17852

Magnetically confined plasmas; Magnetospheric physics

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

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

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

YEAR: 2015     DOI: 10.1002/2015GL066887

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

Observations of discrete magnetosonic waves off the magnetic equator

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

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

YEAR: 2015     DOI: 10.1002/2015GL066255

discrete structure; magnetsonic wave; off-equatorial region

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

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

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

YEAR: 2015     DOI: 10.1002/2015JA021724

pitch angle distributions; Van Allen Probes

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

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

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

YEAR: 2015     DOI: 10.1038/ncomms10096

Van Allen Probes

Wave-particle interactions in the outer radiation belts

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

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

YEAR: 2015     DOI:

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

Electron scattering by magnetosonic waves in the inner magnetosphere

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

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

YEAR: 2015     DOI: 10.1002/2015JA021992

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

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

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

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

YEAR: 2015     DOI: 10.1002/2015JA021829

model for chorus wave

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