Found 12 entries in the Bibliography.
Showing entries from 1 through 12
| 2020 |
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Using seven years of data from the HOPE instrument on the Van Allen Probes, equatorial pitch angle distributions (PADs) of 1 – 50 keV electrons in Earth s inner magnetosphere are investigated statistically. An empirical model of electron equatorial PADs as a function of radial distance, magnetic local time, geomagnetic activity, and electron energy is constructed using the method of Legendre polynomial fitting. Model results show that most equatorial PADs of 1 – 10s of keV electrons in Earth s inner magnetosphere are pan ... Zhao, H.; Friedel, R.; Chen, Y.; Baker, D.; Li, X.; Malaspina, D.; Larsen, B.; Skoug, R.; Funsten, H.; Reeves, G.; Boyd, A.; YEAR: 2020 DOI: https://doi.org/10.1029/2020JA028322 Pitch angle distribution; energetic electrons; Earth s inner magnetosphere; Anisotropy; Chorus wave; statistical analysis; Van Allen Probes |
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Earth s slot region, lying between the outer and inner radiation belts, has been identified as due to a balance between inward radial diffusion and pitch angle (PA) scattering induced by waves. However, recent satellite observations and modeling studies indicate that cosmic ray albedo neutron decay (CRAND) may also play a significant role in energetic electron dynamics in the slot region. In this study, using a drift-diffusion-source model, we investigate the relative contribution of all significant waves and CRAND to the dy ... Xiang, Zheng; Li, Xinlin; Ni, Binbin; Temerin, M.; Zhao, Hong; Zhang, Kun; Khoo, Leng; YEAR: 2020 DOI: https://doi.org/10.1029/2020JA028042 Slot region; Wave-particle interaction; CRAND; energetic electrons; Van Allen Probes |
| 2019 |
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EMIC Wave-Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere While electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron-resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower-energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth\textquoterig ... Blum, L.W.; Artemyev, A.; Agapitov, O.; Mourenas, D.; Boardsen, S.; Schiller, Q.; YEAR: 2019 DOI: 10.1029/2018JA026427 bounce resonance; EMIC wave; energetic electrons; Radiation belts; Van Allen Probes |
| 2018 |
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Generation process of large-amplitude upper band chorus emissions observed by Van Allen Probes We analyze large-amplitude upper-band chorus emissions measured near the magnetic equator by the EMFISIS (Electric and Magnetic Field Instrument Suite and Integrated Science) instrument package onboard the Van Allen Probes. In setting up the parameters of source electrons exciting the emissions based on theoretical analyses and observational results measured by the HOPE (Helium Oxygen Proton Electron) instrument, we calculate threshold and optimum amplitudes with the nonlinear wave growth theory. We find that the optimum amp ... Kubota, Yuko; Omura, Yoshiharu; Kletzing, Craig; Reeves, Geoff; YEAR: 2018 DOI: 10.1029/2017JA024782 Chorus; energetic electrons; nonlinear wave-particle interaction; observation; Radiation belt; Van Allen Probes |
| 2016 |
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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 |
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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 |
| 2015 |
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We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2\textendash6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0\textendash4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes ... Titova, E.; Kozelov, B.; Demekhov, A.; Manninen, J.; Santolik, O.; Kletzing, C.; Reeves, G.; YEAR: 2015 DOI: 10.1002/grl.v42.1510.1002/2015GL064911 energetic electrons; quasiperiodic emissions; Van Allen Probes; VLF waves |
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We report correlated data on nightside chorus waves and energetic electrons during two small storm periods: 1 November 2012 (Dst≈-45) and 14 January 2013 (Dst≈-18). The Van Allen Probes simultaneously observed strong chorus waves at locations L = 5.8 - 6.3, with a lower frequency band 0.1 - 0.5fce and a peak spectral density \~[10-4 nT2/Hz. In the same period, the fluxes and anisotropy of energetic (\~ 10-300 keV) electrons were greatly enhanced in the interval of large negative interplanetary magnetic field Bz. Using a ... He, Yihua; Xiao, Fuliang; Zhou, Qinghua; Yang, Chang; Liu, Si; Baker, D.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; YEAR: 2015 DOI: 10.1002/2015JA021376 chorus wave excitation; energetic electrons; Geomagnetic storm; Van Allen Probes; Van Allen probes results; Wave-particle interaction |
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Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and ma ... Hartley, D.; Chen, Y.; Kletzing, C.; Denton, M.; Kurth, W.; YEAR: 2015 DOI: 10.1002/2014JA020808 chorus waves; EMFISIS; energetic electrons; Radiation belts; Van Allen Probes; wave-particle interactions |
| 2014 |
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The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-art pitch-angle-resolved data from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard the Van Allen Probes, a detailed analysis of 100 s keV electron PADs below L = 4 is performed, in which the PADs is categorized into three types: normal (flux peaking at 90o), cap (exceedingly peaking narrowly around 90o ... Zhao, H.; Li, X.; Blake, J.; Fennell, J.; Claudepierre, S.; Baker, D.; Jaynes, A.; Malaspina, D.; YEAR: 2014 DOI: 10.1002/2014JA020386 energetic electrons; Inner radiation belt; Pitch angle distribution; plasmasphere; Slot region; Van Allen Probes; Wave-particle interaction |
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Comparison of Energetic Electron Intensities Outside and Inside the Radiation Belts The intensities of energetic electrons (~25 \textendash 800 keV) outside and inside Earth\textquoterights radiation belts are reported using measurements from THEMIS and Van Allen Probes during non-geomagnetic storm periods. Three intervals of current disruption/dipolarization events in August, 2013 were selected for comparison. The following results are obtained. (1) Phase space densities (PSDs) for the equatorially mirroring electron population at three values of the first adiabatic invariant (20, 70, and 200 MeV/G) at the ... T. Y. Lui, A.; Mitchell, D.; Lanzerotti, L.; YEAR: 2014 DOI: 10.1002/2014JA020049 Dipolarization; energetic electrons; Radiation belts; substorm; Van Allen Probes |
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We have recently conducted a statistical survey on pitch angle distributions of energetic electrons trapped in the Earth\textquoterights outer radiation belt, and a new empirical model was developed based upon survey results. This model\textemdashrelativistic electron pitch angle distribution (REPAD)\textemdashaims to present statistical pictures of electron equatorial pitch angle distributions, instead of the absolute flux levels, as a function of energy, L shell, magnetic local time, and magnetic activity. To quantify and ... Chen, Yue; Friedel, Reiner; Henderson, Michael; Claudepierre, Seth; Morley, Steven; Spence, Harlan; YEAR: 2014 DOI: 10.1002/jgra.v119.310.1002/2013JA019431 Earth\textquoterights outer radiation belt; energetic electrons; Pitch-angle distributions |
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