Bibliography





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Found 83 entries in the Bibliography.


Showing entries from 51 through 83


2016

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.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2016

YEAR: 2016     DOI: 10.1002/2016JA022370

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

2015

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.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2015

YEAR: 2015     DOI: 10.1002/2015JA021992

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

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

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

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

Published by: Geophysical Research Letters      Published on: 10/2015

YEAR: 2015     DOI: 10.1002/2015GL066107

Chorus; local time distribution; repetition period

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

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

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

Published by: Journal of Geophysical Research: Space Physics      Published on: 10/2015

YEAR: 2015     DOI: 10.1002/2015JA021148

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

Resonant scattering of outer zone relativistic electrons by multiband EMIC waves and resultant electron loss time scales

To improve our understanding of the role of electromagnetic ion cyclotron (EMIC) waves in radiation belt electron dynamics, we perform a comprehensive analysis of EMIC wave-induced resonant scattering of outer zone relativistic (>0.5 MeV) electrons and resultant electron loss time scales with respect to EMIC wave band, L shell, and wave normal angle model. The results demonstrate that while H+-band EMIC waves dominate the scattering losses of ~1\textendash4 MeV outer zone relativistic electrons, it is He+-band and O+-band wa ...

Ni, Binbin; Cao, Xing; Zou, Zhengyang; Zhou, Chen; Gu, Xudong; Bortnik, Jacob; Zhang, Jichun; Fu, Song; Zhao, Zhengyu; Shi, Run; Xie, Lun;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2015

YEAR: 2015     DOI: 10.1002/2015JA021466

electron loss time scales; EMIC waves; outer radiation belt; relativistic electrons; resonant wave-particle interactions

Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged sout ...

Li, W.; Thorne, R.; Bortnik, J.; Baker, D.; Reeves, G.; Kanekal, S.; Spence, H.; Green, J.;

Published by: Geophysical Research Letters      Published on: 09/2015

YEAR: 2015     DOI: 10.1002/2015GL065342

Chorus wave; Electron acceleration; solar wind conditions; Van Allen Probes

Nonlinear Bounce Resonances between Magnetosonic Waves and Equatorially Mirroring Electrons

Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the fluxof these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from a equatorial pitch angle of 90 degrees down to lower values. However this mechanism has not been uniquely identified y ...

Chen, Lunjin; Maldonado, Armando; Bortnik, Jacob; Thorne, Richard; Li, Jinxing; Dai, Lei; Zhan, Xiaoya;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2015

YEAR: 2015     DOI: 10.1002/2015JA021174

bounce resonance; equatorioal noise; magnetosonic waves; nonlinear; Radiation belt; wave particle interaction

Statistical properties of plasmaspheric hiss derived from Van Allen Probes data and their Effects on radiation belt electron dynamics

Plasmaspheric hiss is known to play an important role in controlling the overall structure and dynamics of radiation belt electrons inside the plasmasphere. Using newly available Van Allen Probes wave data, which provide excellent coverage in the entire inner magnetosphere, we evaluate the global distribution of the hiss wave frequency spectrum and wave intensity for different levels of substorm activity. Our statistical results show that observed hiss peak frequencies are generally lower than the commonly adopted value (~55 ...

Li, W.; Ma, Q.; Thorne, R.; Bortnik, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Nishimura, Y.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2015

YEAR: 2015     DOI: 10.1002/2015JA021048

hiss diffusion coefficient; hiss frequency spectrum; Plasmaspheric Hiss; Van Allen Probes

Variability of the pitch angle distribution of radiation belt ultra-relativistic electrons during and following intense geomagnetic storms: Van Allen Probes observations

Fifteen months of pitch angle resolved Van Allen Probes REPT measurements of differential electron flux are analyzed to investigate the characteristic variability of the pitch angle distribution (PAD) of radiation belt ultra-relativistic (>2 MeV) electrons during storm conditions and during the long-term post-storm decay. By modeling the ultra-relativistic electron pitch angle distribution as sinn α, where α is the equatorial pitch angle, we examine the spatio-temporal variations of the n-value. The results show that in ge ...

Ni, Binbin; Zou, Zhengyang; Gu, Xudong; Zhou, Chen; Thorne, Richard; Bortnik, Jacob; Shi, Run; Zhao, Zhengyu; Baker, Daniel; Kanekal, Shrikhanth; Spence, Harlan; Reeves, Geoffrey; Li, Xinlin;

Published by: Journal of Geophysical Research: Space Physics      Published on: 05/2015

YEAR: 2015     DOI: 10.1002/2015JA021065

adiation belt ultra-relativistic electrons; decay timescales; Geomagnetic storms; Pitch angle distribution; resonant wave-particle interactions; Van Allen Probes

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis

A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the POES spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conj ...

de Soria-Santacruz, M.; Li, W.; Thorne, R.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.D.; Blake, J.; Fennell, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 04/2015

YEAR: 2015     DOI: 10.1002/2014JA020941

Plasmaspheric Hiss; POES technique; Van Allen Probes; Waves global model

First Evidence for Chorus at a Large Geocentric Distance as a Source of Plasmaspheric Hiss: Coordinated THEMIS and Van Allen Probes Observation

Recent ray tracing suggests that plasmaspheric hiss can originate from chorus observed outside of the plasmapause. Although a few individual events have been reported to support this mechanism, the number of reported conjugate events is still very limited. Using coordinated observations between THEMIS and Van Allen Probes, we report on an interesting event, where chorus was observed at a large L-shell (~9.8), different from previously reported events at L < 6, but still exhibited a remarkable correlation with hiss observed i ...

Li, W.; Chen, L.; Bortnik, J.; Thorne, R.; Angelopoulos, V.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

Published by: Geophysical Research Letters      Published on: 01/2015

YEAR: 2015     DOI: 10.1002/2014GL062832

Chorus; hiss; wave propagation; Van Allen Probes

2014

Evolution of relativistic outer belt electrons during an extended quiescent period

To effectively study steady loss due to hiss-driven precipitation of relativistic electrons in the outer radiation belt, it is useful to isolate this loss by studying a time of relatively quiet geomagnetic activity. We present a case of initial enhancement and slow, steady decay of 700 keV - 2 MeV electron populations in the outer radiation belt during an extended quiescent period from ~15 December 2012 - 13 January 2013. We incorporate particle measurements from a constellation of satellites, including the Colorado Student ...

Jaynes, A.; Li, X.; Schiller, Q.; Blum, L.; Tu, W.; Turner, D.; Ni, B.; Bortnik, J.; Baker, D.; Kanekal, S.; Blake, J.; Wygant, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2014

YEAR: 2014     DOI: 10.1002/2014JA020125

electron lifetime; hiss waves; pitch angle scattering; precipitation loss; Radiation belts; Van Allen Probes

Initial Measurements of O-ion and He-ion Decay Rates Observed from the Van Allen Probes RBSPICE Instrument

H-ion (~45-keV to ~600-keV), He-ion (~65-keV to ~520-keV), and O-ion (~140-keV to ~1130-keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first nine months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. O ...

Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2014

YEAR: 2014     DOI: 10.1002/2014JA020374

inner magnetosphere; ion decay rates; Spacecraft measurements; Van Allen Probes

Statistical results describing the bandwidth and coherence coefficient of whistler mode waves using THEMIS waveform data

The bandwidths and coherence coefficients of lower band whistler mode waves are analyzed using Time History of Events and Macroscale Interactions during Substorms (THEMIS) waveform data for rising tones, falling tones, and hiss-like emissions separately. We also evaluate their dependences on the spatial location, electron density, the ratio of plasma frequency to local electron gyrofrequency (fpe/fce), and the wave amplitude. Our results show that the bandwidth normalized by the local electron gyrofrequency (fce) of rising a ...

Gao, X.; Li, W.; Thorne, R.; Bortnik, J.; Angelopoulos, V.; Lu, Q.; Tao, X.; Wang, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2014

YEAR: 2014     DOI: 10.1002/2014JA020158

bandwidth; coherence coefficient; nonlinear; quasi-linear; THEMIS; whistler mode waves

Calculation of whistler-mode wave intensity using energetic electron precipitation

The energetic electron population measured by multiple low-altitude POES satellites is used to infer whistlermode wave amplitudes using a physics-based inversion technique. We validate this technique by quantitatively analyzing a conjunction event between the Van Allen Probes and POES, and find that the inferred hiss wave amplitudes from POES electron measurements agree remarkably well with directly measured hiss waves amplitudes. We also use this technique to construct the global distribution of chorus wave intensity with e ...

Li, W.; Ni, B.; Thorne, R.; Bortnik, J.; Green, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

Published by:       Published on: 08/2014

YEAR: 2014     DOI: 10.1109/URSIGASS.2014.6929965

Electron traps; Energy measurement; Plasma measurements; Van Allen Probes

Evidence of stronger pitch angle scattering loss caused by oblique whistler-mode waves as compared with quasi-parallel waves

Wave normal distributions of lower-band whistler-mode waves observed outside the plasmapause exhibit two peaks; one near the parallel direction and the other at very oblique angles. We analyze a number of conjunction events between the Van Allen Probes near the equatorial plane and POES satellites at conjugate low altitudes, where lower-band whistler-mode wave amplitudes were inferred from the two-directional POES electron measurements over 30\textendash100 keV, assuming that these waves were quasi-parallel. For conjunction ...

Li, W.; Mourenas, D.; Artemyev, A.; Agapitov, O.; Bortnik, J.; Albert, J.; Thorne, R.; Ni, B.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

Published by: Geophysical Research Letters      Published on: 08/2014

YEAR: 2014     DOI: 10.1002/2014GL061260

chorus waves; electron precipitation; oblique whistler; pitch angle scattering

Generation of Unusually Low Frequency Plasmaspheric Hiss

It has been reported from Van Allen Probe observations that plasmaspheric hiss intensification in the outer plasmasphere, associated with a substorm injection on Sept 30 2012, occurred with a peak frequency near 100 Hz, well below the typical plasmaspheric hiss frequency range, extending down to ~20 Hz. We examine this event of unusually low frequency plasmaspheric hiss to understand its generation mechanism. Quantitative analysis is performed by simulating wave ray paths via the HOTRAY ray tracing code with measured plasma ...

Chen, Lunjin; Thorne, Richard; Bortnik, Jacob; Li, Wen; Horne, Richard; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Blake, J.; Fennell, J.;

Published by: Geophysical Research Letters      Published on: 08/2014

YEAR: 2014     DOI: 10.1002/2014GL060628

Chorus; Generation; Plasmaspheric Hiss; Ray Tracing; Van Allen Probes

Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm

Local acceleration driven by whistler-mode chorus waves is suggested to be fundamentally important for accelerating seed electron population to ultra-relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus-driven electron acceleration during the 17 March 2013 storm, when Van Allen Probes observed very rapid electron acceleration up to multi MeV within \~15 hours. A clear peak in electron phase space density observed at L* \~ 4 indicates that the internal local acceleration process ...

Thorne, R.; Li, W.; Ma, Q.; Ni, B.; Bortnik, J.;

Published by:       Published on: 08/2014

YEAR: 2014     DOI: 10.1109/URSIGASS.2014.6929882

Atmospheric waves; Van Allen Belts; Van Allen Probes

Evolution of nightside subauroral proton aurora caused by transient plasma sheet flows

While nightside subauroral proton aurora shows rapid temporal variations, the cause of this variability has rarely been investigated. Using well-coordinated observations by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) all-sky imagers, THEMIS satellites in the equatorial magnetosphere, and the low-altitude NOAA 17 satellite, we examined the rapid temporal evolution of subauroral proton aurora in the premidnight sector. An isolated proton aurora occurred soon after an auroral poleward bounda ...

Nishimura, Y.; Bortnik, J.; Li, W.; Lyons, L.; Donovan, E.; Angelopoulos, V.; Mende, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2014

YEAR: 2014     DOI: 10.1002/2014JA020029

EMIC waves; plasma sheet flow burst; plasmasphere; proton aurora; THEMIS ASI; THEMIS satellite

A novel technique to construct the global distribution of whistler mode chorus wave intensity using low-altitude POES electron data

Although magnetospheric chorus plays a significant role in the acceleration and loss of radiation belt electrons, its global evolution during any specific time period cannot be directly obtained by spacecraft measurements. Using the low-altitude NOAA Polar-orbiting Operational Environmental Satellite (POES) electron data, we develop a novel physics-based methodology to infer the chorus wave intensity and construct its global distribution with a time resolution of less than an hour. We describe in detail how to apply the tech ...

Ni, Binbin; Li, Wen; Thorne, Richard; Bortnik, Jacob; Green, Janet; Kletzing, Craig; Kurth, William; Hospodarsky, George; Pich, Maria;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.710.1002/2014JA019935

electron precipitation; global wave distribution; magnetospheric chorus; physics-based technique; wave resonant scattering

Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm

Local acceleration driven by whistler-mode chorus waves is fundamentally important for accelerating seed electron populations to highly relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus-driven electron acceleration during the 17 March 2013 storm, when the Van Allen Probes observed very rapid electron acceleration up to several MeV within ~12 hours. A clear radial peak in electron phase space density (PSD) observed near L* ~4 indicates that an internal local acceleration proce ...

Li, W.; Thorne, R.; Ma, Q.; Ni, B.; Bortnik, J.; Baker, D.; Spence, H.; Reeves, G.; Kanekal, S.; Green, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Blake, J.; Fennell, J.; Claudepierre, S.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.610.1002/2014JA019945

Van Allen Probes

Competing source and loss mechanisms due to wave-particle interactions in Earth\textquoterights outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm

Drastic variations of Earth\textquoterights outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave-particle interactions are critically important. Using 15 spacecraft including NASA\textquoterights Van Allen Probes, THEMIS, and SAMPEX missions and NOAA\textquoterights GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm\textquoterights main phase drop ...

Turner, D.; Angelopoulos, V.; Li, W.; Bortnik, J.; Ni, B.; Ma, Q.; Thorne, R.; Morley, S.; Henderson, M.; Reeves, G.; Usanova, M.; Mann, I.; Claudepierre, S.; Blake, J.; Baker, D.; Huang, C.-L.; Spence, H.; Kurth, W.; Kletzing, C.; Rodriguez, J.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 03/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.310.1002/2014JA019770

Van Allen Probes

Resonant scattering of energetic electrons by unusual low-frequency hiss

We quantify the resonant scattering effects of the unusual low-frequency dawnside plasmaspheric hiss observed on 30 September 2012 by the Van Allen Probes. In contrast to normal (~100\textendash2000 Hz) hiss emissions, this unusual hiss event contained most of its wave power at ~20\textendash200 Hz. Compared to the scattering by normal hiss, the unusual hiss scattering speeds up the loss of ~50\textendash200 keV electrons and produces more pronounced pancake distributions of ~50\textendash100 keV electrons. It is demonstrate ...

Ni, Binbin; Li, Wen; Thorne, Richard; Bortnik, Jacob; Ma, Qianli; Chen, Lunjin; Kletzing, Craig; Kurth, William; Hospodarsky, George; Reeves, Geoffrey; Spence, Harlan; Blake, Bernard; Fennell, Joseph; Claudepierre, Seth;

Published by: Geophysical Research Letters      Published on: 03/2014

YEAR: 2014     DOI: 10.1002/2014GL059389

Van Allen Probes

Quantifying hiss-driven energetic electron precipitation: A detailed conjunction event analysis

We analyze a conjunction event between the Van Allen Probes and the low-altitude Polar Orbiting Environmental Satellite (POES) to quantify hiss-driven energetic electron precipitation. A physics-based technique based on quasi-linear diffusion theory is used to estimate the ratio of precipitated and trapped electron fluxes (R), which could be measured by the two-directional POES particle detectors, using wave and plasma parameters observed by the Van Allen Probes. The remarkable agreement between modeling and observations sug ...

Li, W.; Ni, B.; Thorne, R.; Bortnik, J.; Nishimura, Y.; Green, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Blake, J.; Fennell, J.; Claudepierre, S.; Gu, X.;

Published by: Geophysical Research Letters      Published on: 02/2014

YEAR: 2014     DOI: 10.1002/2013GL059132

Van Allen Probes

Quiet time observations of He ions in the inner magnetosphere as observed from the RBSPICE instrument aboard the Van Allen Probes mission

He ions contribute to Earth\textquoterights ring current energy and species population density and are important in understanding ion transport and charge exchange processes in the inner magnetosphere. He ion flux measurements made by the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument are presented in this paper. Particular focus is centered on geomagnetically quiet intervals in late 2012 and 2013 that show the flux, L-shell, and energy (65 keV to 518 keV) morphology of ring curr ...

Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob;

Published by: Geophysical Research Letters      Published on: 02/2014

YEAR: 2014     DOI: 10.1002/2013GL059175

Van Allen Probes

2013

Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus

Recent analysis of satellite data obtained during the 9 October 2012 geomagnetic storm identified the development of peaks in electron phase space density1, which are compelling evidence for local electron acceleration in the heart of the outer radiation belt2, 3, but are inconsistent with acceleration by inward radial diffusive transport4, 5. However, the precise physical mechanism responsible for the acceleration on 9 October was not identified. Previous modelling has indicated that a magnetospheric electromagnetic emissio ...

Thorne, R.; Li, W.; Ni, B.; Ma, Q.; Bortnik, J.; Chen, L.; Baker, D.; Spence, H.; Reeves, G.; Henderson, M.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Blake, J.; Fennell, J.; Claudepierre, S.; Kanekal, S.;

Published by: Nature      Published on: 12/2013

YEAR: 2013     DOI: 10.1038/nature12889

RBSP; Van Allen Probes

Resonant scattering and resultant pitch angle evolution of relativistic electrons by plasmaspheric hiss

We perform a comprehensive analysis to evaluate hiss-induced scattering effect on the pitch angle evolution and associated decay processes of relativistic electrons. The results show that scattering by the equatorial, highly oblique hiss component is negligible. Quasi-parallel approximation is good for evaluation of hiss-driven electron scattering rates <= 2 MeV. However, realistic wave propagation angles as a function of latitude must be considered to accurately quantify hiss scattering rates above 2 MeV, and ambient plasma ...

Ni, Binbin; Bortnik, Jacob; Thorne, Richard; Ma, Qianli; Chen, Lunjin;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2013

YEAR: 2013     DOI: 10.1002/2013JA019260

Van Allen Probes

Constructing the global distribution of chorus wave intensity using measurements of electrons by the POES satellites and waves by the Van Allen Probes

We adopt a physics-based technique to infer chorus wave amplitudes from the low-altitude electron population (30\textendash100 keV) measured by multiple Polar Orbiting Environmental Satellites (POES), which provide extensive coverage over a broad region in L-shell and magnetic local time (MLT). This technique is validated by analyzing conjunction events between the Van Allen Probes measuring chorus wave amplitudes near the equator and POES satellites measuring the 30\textendash100 keV electron population at the conjugate low ...

Li, W.; Ni, B.; Thorne, R.; Bortnik, J.; Green, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.;

Published by: Geophysical Research Letters      Published on: 09/2013

YEAR: 2013     DOI: 10.1002/grl.v40.1710.1002/grl.50920

Van Allen Probes

An unusual enhancement of low-frequency plasmaspheric hiss in the outer plasmasphere associated with substorm-injected electrons

Both plasmaspheric hiss and chorus waves were observed simultaneously by the two Van Allen Probes in association with substorm-injected energetic electrons. Probe A, located inside the plasmasphere in the postdawn sector, observed intense plasmaspheric hiss, whereas Probe B observed chorus waves outside the plasmasphere just before dawn. Dispersed injections of energetic electrons were observed in the dayside outer plasmasphere associated with significant intensification of plasmaspheric hiss at frequencies down to ~20 Hz, m ...

Li, W.; Thorne, R.; Bortnik, J.; Reeves, G.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Blake, J.; Fennell, J.; Claudepierre, S.; Wygant, J.; Thaller, S.;

Published by: Geophysical Research Letters      Published on: 08/2013

YEAR: 2013     DOI: 10.1002/grl.50787

Van Allen Probes

Evolution and slow decay of an unusual narrow ring of relativistic electrons near L ~ 3.2 following the September 2012 magnetic storm

A quantitative analysis is performed on the decay of an unusual ring of relativistic electrons between 3 and 3.5 RE, which was observed by the Relativistic Electron Proton Telescope instrument on the Van Allen probes. The ring formed on 3 September 2012 during the main phase of a magnetic storm due to the partial depletion of the outer radiation belt for L > 3.5, and this remnant belt of relativistic electrons persisted at energies above 2 MeV, exhibiting only slow decay, until it was finally destroyed during another magneti ...

Thorne, R.; Li, W.; Ni, B.; Ma, Q.; Bortnik, J.; Baker, D.; Spence, H.; Reeves, G.; Henderson, M.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Turner, D.; Angelopoulos, V.;

Published by: Geophysical Research Letters      Published on: 06/2013

YEAR: 2013     DOI: 10.1002/grl.50627

RBSP; Van Allen Probes

A novel technique for rapid L* calculation: algorithm and implementation

Computing the magnetic drift invariant, L*, rapidly and accurately has always been a challenge to magnetospheric modelers, especially given the im- portance of this quantity in the radiation belt community. Min et al. (2013) proposed a new method of calculating L* using the principle of energy con- servation. Continuing with the approach outlined therein, the present pa- per focuses on the technical details of the algorithm to outline the implemen- tation, systematic analysis of accuracy, and verification of the speed of the ...

Min, Kyungguk; Bortnik, J.; Lee, Jeongwoo;

Published by: Journal of Geophysical Research      Published on: 05/2013

YEAR: 2013     DOI: 10.1002/jgra.50250

calculating L*; rapid L* calculation; RBSP; Van Allen Probes

A novel technique for rapid L* calculation using UBK coordinates

[1] The magnetic drift invariant (L*) is an important quantity used for tracking and organizing particle dynamics in the radiation belts, but its accurate calculation has been computationally expensive in the past, thus making it difficult to employ this quantity in real-time space weather applications. In this paper, we propose a new, efficient method to calculate L* using the principle of energy conservation. This method uses Whipple\textquoterights (U, B, K) coordinates to quickly and accurately determine trajectories of ...

Min, Kyungguk; Bortnik, J.; Lee, Jeongwoo;

Published by: Journal of Geophysical Research      Published on: 01/2013

YEAR: 2013     DOI: 10.1029/2012JA018177

Generalized L value; L star; RBSP; Van Allen Probes

2006

Observation of two distinct, rapid loss mechanisms during the 20 November 2003 radiation belt dropout event

The relativistic electron dropout event on 20 November 2003 is studied using data from a number of satellites including SAMPEX, HEO, ACE, POES, and FAST. The observations suggest that the dropout may have been caused by two separate mechanisms that operate at high and low L-shells, respectively, with a separation at L \~ 5. At high L-shells (L > 5), the dropout is approximately independent of energy and consistent with losses to the magnetopause aided by the Dst effect and outward radial diffusion which can deplete relativis ...

Bortnik, J.; Thorne, R.; O\textquoterightBrien, T.; Green, J.; Strangeway, R.; . Y. Shprits, Y; Baker, D.;

Published by: Journal of Geophysical Research      Published on: 12/2006

YEAR: 2006     DOI: 10.1029/2006JA011802

Local Loss due to VLF/ELF/EMIC Waves



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