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Van Allen Probes Bibliography is from August 2012 through September 2021 Notice:
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Found 32 entries in the Bibliography.
Showing entries from 1 through 32
| 2020 |
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In this study we focus on the radiation belt dynamics driven by the geomagnetic storms during September 2017. Besides the long-lasting three-belt structures of ultrarelativistic electrons (>2 MeV, existing for tens of days), which has been studied intensively during the Van Allen Probe era, it is found that magnetospheric electrons of hundreds of keVs can also have three-belt structures at similar L extent during storm time. Measurements of 500–800 keV electrons from MagEIS instrument onboard Van Allen Probes show double- ... Hao, Y.; Zong, Q.-G.; Zhou, X.-Z.; Zou, H.; Rankin, R.; Sun, Y.; Chen, X.; Liu, Y.; Fu, S; Baker, D.; Spence, H.; Blake, J.; Reeves, G.; Claudepierre, S.; Published by: Journal of Geophysical Research: Space Physics Published on: 07/2020 YEAR: 2020 DOI: https://doi.org/10.1029/2020JA028031 storage ring; three-belt structure; hiss wave; electron lifetime; Radial Transport; Van Allen Probes |
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Evolutions of equatorial ring current ions during a magnetic storm In this paper, we present evolutions of the phase space density (PSD) spectra of ring current (RC) ions based on observations made by Van Allen Probe B during a geomagnetic storm on 23–24 August 2016. By analyzing PSD spectra ratios from the initial phase to the main phase of the storm, we find that during the main phase, RC ions with low magnetic moment μ values can penetrate deeper into the magnetosphere than can those with high μ values, and that the μ range of PSD enhancement meets the relationship: S(O+) > S(He+) > ... Huang, Zheng; Yuan, Zhigang; Yu, Xiongdong; Published by: Earth and Planetary Physics Published on: 03/2020 YEAR: 2020 DOI: 10.26464/epp2020019 ULF waves; ring current; wave-particle interactions; Radial Transport; Geomagnetic storm; Decay rates; Van Allen Probes |
| 2018 |
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During geomagnetic storms the intensities of the outer radiation belt electron population can exhibit dramatic variability. Deep depletions in intensity during the main phase are followed by increases during the recovery phase, often to levels that significantly exceed their pre-storm values. To study these processes, we simulate the evolution of the outer radiation belt during the 17 March 2013 geomagnetic storm using our newly-developed radiation belt model (CHIMP) based on test particle and coupled 3D ring current and glo ... Sorathia, K.; Ukhorskiy, A; Merkin, V.; Fennell, J.; Claudepierre, S.; Published by: Journal of Geophysical Research: Space Physics Published on: 06/2018 YEAR: 2018 DOI: 10.1029/2018JA025506 dropout; Geomagnetic storms; magnetopause loss; Radial Transport; Radiation belt; Van Allen Probes |
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Observations during the main phase of geomagnetic storms reveal an anti-correlation between the occurrence of broadband low frequency electromagnetic waves and outer radiation belt electron flux. We show that the drift-bounce motion of electrons in the magnetic field of these waves leads to rapid electron transport. For observed spectral energy densities it is demonstrated that the wave magnetic field can drive radial diffusion via drift-bounce resonance on timescales less than a drift orbit. This process may provide outward ... Chaston, C.; Bonnell, J.; Wygant, J.; Reeves, G.; Baker, D.; Melrose, D.; Published by: Geophysical Research Letters Published on: 02/2018 YEAR: 2018 DOI: 10.1002/2017GL076362 Alfven waves; Geomagnetic storms; Radial Transport; Radiation belts; Van Allen Probes |
| 2015 |
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Global Storm-Time Depletion of the Outer Electron Belt The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by ordersof magnitude at different spatial and temporal scale. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase deplet ... Ukhorskiy, A; Sitnov, M.; Millan, R.; Kress, B.; Fennell, J.; Claudepierre, S.; Barnes, R.; Published by: Journal of Geophysical Research: Space Physics Published on: 03/2015 YEAR: 2015 DOI: 10.1002/2014JA020645 dropout; Geomagnetic storms; magnetopause loss; Radial Transport; Radiation belt; ring current; Van Allen Probes |
| 2008 |
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Radial transport in the outer radiation belt due to global magnetospheric compressions Earth\textquoterights outer radiation belt is populated by relativistic electrons that produce a complex dynamical response to varying geomagnetic activity. One fundamental process defining global state of the belt is radial transport of electrons across their drift shells. Radial transport is induced by resonant interaction of electron drift motion with ULF oscillations of electric and magnetic fields and is commonly believed to be a diffusive process. The goal of this paper is the analysis of radial transport due to typica ... Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.07.018 |
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In this paper, we focus on the modeling of radial transport in the Earth\textquoterights outer radiation belt. A historical overview of the first observations of the radiation belts is presented, followed by a brief description of radial diffusion. We describe how resonant interactions with poloidal and toroidal components of the ULF waves can change the electron\textquoterights energy and provide radial displacements. We also present radial diffusion and guiding center simulations that show the importance of radial transpor ... SHPRITS, Y; ELKINGTON, S; MEREDITH, N; SUBBOTIN, D; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.06.008 |
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[1] The interaction between relativistic, equatorially mirroring electrons and Pc5 Ultra Low Frequency (ULF) waves in the magnetosphere is investigated using a numerical MagnetoHydroDynamic (MHD) model for waves and a test-kinetic model for electron phase space density (PSD). The temporal and spatial characteristics of a ULF wave packet are constrained using ground-based observations of narrowband ULF activity following a geomagnetic storm on 24 March 1991, which occurred from 1200 to 1340 Universal Time (UT). A salient feat ... Published by: Journal of Geophysical Research Published on: 10/2008 YEAR: 2008 DOI: 10.1029/2008JA013254 |
| 2007 |
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The effect of ULF compressional modes and field line resonances on relativistic electron dynamics The adiabatic, drift-resonant interaction between relativistic, equatorially mirroring electrons and a ULF compressional wave that couples to a field line resonance (FLR) is modelled. Investigations are focussed on the effect of azimuthal localisation in wave amplitude on the electron dynamics. The ULF wave fields on the equatorial plane (r , φ ) are modelled using a box model [Zhu, X., Kivelson, M.G., 1988. Analytic formulation and quantitative solutions of the coupled ULF wave problem. J. Geophys. Res. 93(A8), 8602\text ... Degeling, A.; Rankin, R.; Kabin, K.; Marchand, R.; Mann, I.R.; Published by: Planetary and Space Science Published on: 04/2007 YEAR: 2007 DOI: 10.1016/j.pss.2006.04.039 |
| 2006 |
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In an MHD particle simulation of the September 1998 magnetic storm the evolution of the radiation belt electron radial flux profile appears to be diffusive, and diffusion caused by ULF waves has been invoked as the probable mechanism. In order to separate adiabatic and nonadiabatic effects and to investigate the radial diffusion mechanism during this storm, in this work we solve a radial diffusion equation with ULF wave diffusion coefficients and a time-dependent outer boundary condition, and the results are compared with th ... Fei, Yue; Chan, Anthony; Elkington, Scot; Wiltberger, Michael; Published by: Journal of Geophysical Research Published on: 12/2006 YEAR: 2006 DOI: 10.1029/2005JA011211 |
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In the present work, a test particle simulation is performed in a model of analytic Ultra Low Frequency, ULF, perturbations in the electric and magnetic fields of the Earth\textquoterights magnetosphere. The goal of this work is to examine if the radial transport of energetic particles in quiet-time ULF magnetospheric perturbations of various azimuthal mode numbers can be described as a diffusive process and be approximated by theoretically derived radial diffusion coefficients. In the model realistic compressional electroma ... Sarris, T.; Li, X.; Temerin, M.; Published by: Annales Geophysicae Published on: 10/2006 YEAR: 2006 DOI: 10.5194/angeo-24-2583-2006 |
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A review of ULF interactions with radiation belt electrons Energetic particle fluxes in the outer zone radiation belts can vary over orders of magnitude on a variety of timescales. Power at ULF frequencies, on the order of a few millihertz, have been associated with changes in flux levels among relativis- tic electrons comprising the outer zone of the radiation belts. Power in this part of the spectrum may occur as a result of a number of processes, including internally- generated waves induced by plasma instabilities, and externally generated processes such as shear instabilities a ... Published by: Published on: YEAR: 2006 DOI: 10.1029/169GM12 |
| 2005 |
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Impact of toroidal ULF waves on the outer radiation belt electrons Relativistic electron fluxes in the outer radiation belt exhibit highly variable complex behavior. Previous studies have established a strong correlation of electron fluxes and the inner magnetospheric ULF waves in the Pc 3\textendash5 frequency range. Resonant interaction of ULF waves with the drift motion of radiation belt electrons violates their third adiabatic invariant and consequently leads to their radial transport. If the wave-particle interaction has a stochastic character, then the electron transport is diffusive. ... Ukhorskiy, A; Takahashi, K; Anderson, B.; Korth, H.; Published by: Journal of Geophysical Research Published on: 10/2005 YEAR: 2005 DOI: 10.1029/2005JA011017 |
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The influence of ultralow frequency (ULF) waves in the Pc5 frequency range on radiation belt electrons in a compressed dipole magnetic field is examined. This is the first analysis in three dimensions utilizing model ULF wave electric and magnetic fields on the guiding center trajectories of relativistic electrons. A model is developed, describing magnetic and electric fields associated with poloidal mode Pc5 ULF waves. The frequency and L dependence of the ULF wave power are included in this model by incorporating published ... Perry, K.; Hudson, M.; Elkington, S.; Published by: Journal of Geophysical Research Published on: 03/2005 YEAR: 2005 DOI: 10.1029/2004JA010760 |
| 2004 |
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Time dependent radial diffusion modeling of relativistic electrons with realistic loss rates Model simulations are compared to the typically observed evolution of MeV electron fluxes during geomagnetic storms to investigate whether radial diffusion alone can account for the observed variability and to estimate the effect of electron lifetimes. We demonstrate that knowledge of lifetimes is crucial for understanding the radial structure of the storm-time radiation belts and their temporal evolution. Our model results suggest that outer zone lifetimes at 1 MeV are on the order of few days during quite-times and less th ... Published by: Geophysical Research Letters Published on: 04/2004 YEAR: 2004 DOI: 10.1029/2004GL019591 |
| 2003 |
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Using the data from the NOAA and Exos-D satellites during the 3 November 1993 magnetic storm, the dynamic behavior of electrons with energies from a few tens of kiloelectronvolts to a few and its relation to plasma waves were examined. After the late main phase, relativistic electron flux started to recover from the heart of the outer radiation belt, where the cold plasma density was extremely low, and intense whistler mode chorus emissions were detected. The phase space density showed a peak in the outer belt, and the peak ... Published by: Journal of Geophysical Research Published on: 03/2003 YEAR: 2003 DOI: 10.1029/2001JA007542 |
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Resonant acceleration and diffusion of outer zone electrons in an asymmetric geomagnetic field [1] The outer zone radiation belt consists of energetic electrons drifting in closed orbits encircling the Earth between \~3 and 7 RE. Electron fluxes in the outer belt show a strong correlation with solar and magnetospheric activity, generally increasing during geomagnetic storms with associated high solar wind speeds, and increasing in the presence of magnetospheric ULF waves in the Pc-5 frequency range. In this paper, we examine the influence of Pc-5 ULF waves on energetic electrons drifting in an asymmetric, compressed d ... Published by: Journal of Geophysical Research Published on: 03/2003 YEAR: 2003 DOI: 10.1029/2001JA009202 |
| 2000 |
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The response of outer radiation belt relativistic electrons to the October 9, 1990, magnetic storm is analyzed in detail using a radial diffusion model and data from the Combined Release and Radiation Effects Satellite (CRRES) and the Los Alamos National Laboratory (LANL) geosynchronous satellite 1989-046. Electron measurements are expressed in terms of phase space density as a function of the three adiabatic invariants determined from CRRES magnetic field data and the Tsyganenko 1989 Kp-dependent magnetic field model. The r ... Published by: Journal of Geophysical Research Published on: 01/2000 YEAR: 2000 DOI: 10.1029/1999JA900344 |
| 1999 |
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There has been increasing evidence that Pc-5 ULF oscillations play a fundamental role in the dynamics of outer zone electrons. In this work we examine the adiabatic response of electrons to toroidal-mode Pc-5 field line resonances using a simplified magnetic field model. We find that electrons can be adiabatically accelerated through a drift-resonant interaction with the waves, and present expressions describing the resonance condition and half-width for resonant interaction. The presence of magnetospheric convection electri ... Elkington, Scot; Hudson, M.; Chan, Anthony; Published by: Geophysical Research Letters Published on: 11/1999 YEAR: 1999 DOI: 10.1029/1999GL003659 |
| 1988 |
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Simultaneous Radial and Pitch Angle Diffusion in the Outer Electron Radiation Belt A solution of the bimodal (radial and pitch angle) diffusion equation for the radiation belts is developed with special regard for the requirements of satellite radiation belt data analysis. In this paper, we use this solution to test the bimodal theory of outer electron belt diffusion by confronting it with satellite data. Satellite observations, usually over finite volumes of (L, t) space, are seldom sufficient in space-time duration to cover the relaxation to equilibrium of the entire radiation belt. Since time scales of ... Chiu, Y.; Nightingale, R.; Rinaldi, M.; Published by: Journal of Geophysical Research Published on: 04/1988 YEAR: 1988 DOI: 10.1029/JA093iA04p02619 |
| 1981 |
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An account is given of measurements of electrons made by the LLNL magnetic electron spectrometer (60\textendash3000 keV in seven differential energy channels) on the Ogo 5 satellite in the earth\textquoterights outer-belt regions during 1968 and early 1969. The data were analyzed to identify those features dominated by pitch angle and radial diffusion; in doing so all aspects of phase space covered by the data were studied, including pitch angle distributions and spectral features, as well as decay rates. The pitch angle dis ... West, H.; Buck, R.; Davidson, G.; Published by: Journal of Geophysical Research Published on: 04/1981 YEAR: 1981 DOI: 10.1029/JA086iA04p02111 |
| 1979 |
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Direct Evaluation of the Radial Diffusion Coefficient near L = 6 Due to Electric Field Fluctuations The radial diffusion coefficient for radiation belt particles near L=6 has been calculated from the measured electric field fluctuations. Simultaneous balloon flights in August 1974 from six auroral zone sites ranging 180\textdegree in magnetic longitude produced the electric field data. The large scale slowly varying ionospheric electric fields from these flights have been mapped to the equator during the quiet magnetic conditions of this campaign. These mapped equatorial electric fields were then Fourier transformed in spa ... Published by: Journal of Geophysical Research Published on: 06/1979 YEAR: 1979 DOI: 10.1029/JA084iA06p02559 |
| 1973 |
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Measurements at conjugate points on the ground near L = 4 of the power spectra of magnetic-field fluctuations in the frequency range 0.5 to 20 mHz are used as a means of estimating daily values for the relativistic-electron radial-diffusion coefficient DLL for two periods in December 1971 and January 1972. The values deduced for L-10 DLL show a strong variation with magnetic activity, as measured by the Fredricksburg magnetic index KFR. The radial-diffusion coefficient typically increases by a factor of \~10 for a unit incre ... Lanzerotti, L.; Morgan, Caroline; Published by: Journal of Geophysical Research Published on: 08/1973 YEAR: 1973 DOI: 10.1029/JA078i022p04600 |
| 1972 |
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Inner-Zone Energetic-Electron Repopulation by Radial Diffusion A quantitative study of the intrusion of natural electrons into the inner radiation zone during and after the geomagnetic storm of September 2, 1966, shows that the transport is consistent with a radial-diffusion mechanism in which the first two invariants are conserved. Except for the 3-day period of the storm main phase when data were missing, the radial-diffusion coefficient is D = 2.7 \texttimes 10-5 L7.9 μ-0.5 day-1 in the range 1.7 <= L <= 2.6 and 13.3 <= μ <= 27.4 Mev gauss-1. This value could be produced by variati ... Tomassian, Albert; Farley, Thomas; Vampola, Alfred; Published by: Journal of Geophysical Research Published on: 07/1972 YEAR: 1972 DOI: 10.1029/JA077i019p03441 |
| 1970 |
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Radial Diffusion of Outer-Zone Electrons: An Empirical Approach to Third-Invariant Violation The near-equatorial fluxes of outer-zone electrons (E>0.5 Mev and E>1.9 Mev) measured by an instrument on the satellite Explorer 15 following the geomagnetic storm of December 17\textendash18, 1962, are used to determine the electron radial diffusion coefficients and electron lifetimes as functions of L for selected values of the conserved first invariant \textmu. For each value of \textmu, the diffusion coefficient is assumed to be time-independent and representable in the form D = DnLn. The diffusion coefficients and lifet ... Lanzerotti, L.; Maclennan, C.; Schulz, Michael; Published by: Journal of Geophysical Research Published on: 10/1970 YEAR: 1970 DOI: 10.1029/JA075i028p05351 |
| 1969 |
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Radial Diffusion of Starfish Electrons A study of the change in electron intensities in the Starfish electron belt from January 1, 1963, to November 3, 1965, indicates that radial diffusion, both inward and outward from L of 1.40, was a significant loss mechanism for these electrons during this period. For L values of 1.20 and below, the indicated steepening of the pitch-angle distributions during this period has been interpreted as the result of a radial diffusion source for each L shell concentrated near the geomagnetic equator. Since pitch-angle diffusion life ... Published by: Journal of Geophysical Research Published on: 07/1969 YEAR: 1969 DOI: 10.1029/JA074i014p03591 |
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Convection Electric Fields and the Diffusion of Trapped Magnetospheric Radiation We explore here the possible importance of time-dependent convection electric fields as an agent for diffusing trapped magnetospheric radiation inward toward the earth. By using a formalism (Birmingham, Northrop, and Fälthammar, 1967) based on first principles, and by adopting a simple model for the magnetosphere and its electric field, we succeed in deriving a one-dimensional diffusion equation to describe statistically the loss-free motion of mirroring particles with arbitrary but conserved values of the first two adiabat ... Published by: Journal of Geophysical Research Published on: 05/1969 YEAR: 1969 DOI: 10.1029/JA074i009p02169 |
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Diffusion of Equatorial Particles in the Outer Radiation Zone Expansions and contractions of the permanently compressed magnetosphere lead to the diffusion of equatorially trapped particles across drift shells. A general technique for obtaining the electric fields induced by these expansions and contractions is described and applied to the Mead geomagnetic field model. The resulting electric drifts are calculated and are superimposed upon the gradient drift executed by a particle that conserves its first (μ) and second (J = 0) adiabatic invariants. The noon-midnight asymmetry of the u ... Schulz, Michael; Eviatar, Aharon; Published by: Journal of Geophysical Research Published on: 05/1969 YEAR: 1969 DOI: 10.1029/JA074i009p02182 |
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Particle fluxes in the outer geomagnetic field The outer geomagnetic field comprises the outer radiation belt, consisting of electrons with energies of 104\textendash107 ev, and the unstable radiation zone. The outer radiation belt is bounded on its inner side by a gap, which is at various times located at a distance of 2.2\textendash3.5 RE and in which a considerable precipitation of electrons from radiation belts occurs, possibly owing to a high intensity of electromagnetic waves. The boundary separating the outer radiation belt from the unstable radiation zone is at Î ... Vernov, S.; Gorchakov, E.; Kuznetsov, S.; Logachev, Yu.; Sosnovets, E.; Stolpovsky, V.; Published by: Reviews of Geophysics Published on: 02/1969 YEAR: 1969 DOI: 10.1029/RG007i001p00257 |
| 1968 |
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Radial Diffusion Coefficient for Electrons at 1.76 < L < 5 Radial diffusion by nonconservation of the third adiabatic invariant of particle motion is assumed in analyzing experiments in which electrons appeared to move across field lines. Time-dependent solutions of the Fokker-Planck diffusion equation are obtained numerically and fitted to the experimental results by adjusting the diffusion coefficient. Values deduced for the diffusion coefficient vary from 1.3 \texttimes 10-5 RE\texttwosuperior/day at L = 1.76 to 0.10 RE\texttwosuperior/day at L = 5. In the interval 2.6 < L < 5, t ... Published by: Journal of Geophysical Research Published on: 12/1968 YEAR: 1968 DOI: 10.1029/JA073i023p07231 |
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Radial Diffusion Coefficient for Electrons at Low L Values An empirical evaluation of the diffusion coefficient for trapped electrons diffusing across low L shells is obtained by adjusting the coefficient to account for the observed radial profile and the long-term decay rate of the trapped electron flux. The diffusion mechanism is not identified, but it is assumed that the adiabatic invariants \textmu and J are conserved. The average value of the coefficient for electrons > 1.6 Mev energy is found to decrease monotonically from \~4 \texttimes 10-6 RE\texttwosuperior/day at L = 1.16 ... Published by: Journal of Geophysical Research Published on: 02/1968 YEAR: 1968 DOI: 10.1029/JA073i003p01013 |
| 1965 |
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Effects of time-dependent electric fields on geomagnetically trapped radiation. Large-scale electric potential fields in the magnetosphere are generally invoked in theories of the aurora. It is shown in the present article that irregular fluctuations of such fields cause a random radial motion of trapped energetic particles by violating the third adiabatic invariant. When the first and second invariants are conserved, any radial motion of the particles is associated with a corresponding energy change. Some particles move outward and others inward; but, if there is a source in the outer magnetosphere and ... Published by: Journal of Geophysical Research Published on: 06/1965 YEAR: 1965 DOI: 10.1029/JZ070i011p02503 |
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