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Authors: Yu J., Li L.Y., Cao J. B., Reeves G D, Baker D N, et al.
Title: The influences of solar wind pressure and interplanetary magnetic field on global magnetic field and outer radiation belt electrons
Abstract: Using the Van Allen Probe in-situ measured magnetic field and electron data, we examine the solar wind dynamic pressure and interplanetary magnetic field (IMF) effects on global magnetic field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2nPa) cause the dayside magnetic field increase and the nightside magnetic field reduction, whereas the large southward IMFs (Bz-IMF < -2nT) mainly lead to the decrease of the nightside magnetic field. In the dayside increased magnetic field region (MLT ~ 06:00 - 18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90o (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distrib. . .
Date: 06/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL069029 Available at: http://doi.wiley.com/10.1002/2016GL069029
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Authors: Khoo Leng Ying, Li Xinlin, Zhao Hong, Sarris Theodore, Xiang Zheng, et al.
Title: On the Initial Enhancement of Energetic Electrons and the Innermost Plasmapause Locations: CME-Driven Storm Periods
Abstract: Using Van Allen Probes’ observations and established plasmapause location (Lpp) models, we investigate the relationship between the location of the initial enhancement (IE) of energetic electrons and the innermost (among all magnetic local time sectors) Lpp over five intense storm periods. Our study reveals that the IE events for 30 keV to 2MeV electrons always occurred outside of the innermost Lpp. On average, the inner extent of the IE events (LIE) for <800 keV electrons was closer to the innermost Lpp when compared to the LIE for >800 keV electrons that was found consistently at ~1.5 RE outside of the innermost Lpp. The IE of 10s keV electrons was observed before the IE of 100s keV electrons, and the IE of >800 keV electrons was observed on average 12.6±2.3 hours after the occurrence. . .
Date: 10/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026074 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026074
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Authors: Gerrard Andrew, Lanzerotti Louis, Gkioulidou Matina, Mitchell Donald, Manweiler Jerry, et al.
Title: Initial Measurements of O-ion and He-ion Decay Rates Observed from the Van Allen Probes RBSPICE Instrument
Abstract: 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. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L-shells, on the orderof ~0.8-day at L-shells of 3–4, and decay more slowly with higher L-she. . .
Date: 11/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020374 Available at: http://doi.wiley.com/10.1002/2014JA020374
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Authors: Foster John C, and Erickson Philip J.
Title: Initial observations of plasma waves in the sub-auroral polarization stream with the Van Allen Probes
Abstract: The Sub-Auroral Polarization Stream (SAPS) is a geospace boundary layer phenomenon associated with the interaction of the warm plasma of the magnetospheric ring current with the cold ions and electrons of the outer plasmasphere [1]. Driven by ring current enhancements during magnetospheric disturbances, SAPS location, intensity, and characteristics are greatly influenced by the underlying ionosphere. Strong M-I coupling by means of field-aligned currents creates a high-speed (>1000 m/s) westward plasma flow channel in the ionosphere at pre-midnight/post-noon local times which is readily observable by incoherent scatter [2] and HF radars and in plasma drift observations by low-altitude spacecraft (e.g. DMSP). The fast ionospheric flows generate E-region irregularities providing for addition. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929852 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929852
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Authors: Yu Yiqun, ätter Lutz, Jordanova Vania K., Zheng Yihua, Engel Miles, et al.
Title: Initial Results From the GEM Challenge on the Spacecraft Surface Charging Environment
Abstract: Spacecraft surface charging during geomagnetically disturbed times is one of the most important causes of satellite anomalies. Predicting the surface charging environment is one prevalent task of the geospace environment models. Therefore, the Geospace Environment Modeling (GEM) Focus Group “Inner Magnetosphere Cross‐energy/Population Interactions” initiated a community‐wide challenge study to assess the capability of several inner magnetosphere ring current models in determining surface charging environment for the Van Allen Probes orbits during the 17 March 2013 storm event. The integrated electron flux between 10 and 50 keV is used as the metrics. Various skill scores are applied to quantitatively measure the modeling performance against observations. Results indicate that no mo. . .
Date: 02/2019 Publisher: Space Weather DOI: 10.1029/2018SW002031 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002031
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Authors: Agapitov O. V., Artemyev A. V., Mourenas D., Kasahara Y., and Krasnoselskikh V.
Title: Inner belt and slot region electron lifetimes and energization rates based on AKEBONO statistics of whistler waves
Abstract: Global statistics of the amplitude distributions of hiss, lightning-generated, and other whistler mode waves from terrestrial VLF transmitters have been obtained from the EXOS-D (Akebono) satellite in the Earth's plasmasphere and fitted as functions of L and latitude for two geomagnetic activity ranges (Kp<3 and Kp>3). In particular, the present study focuses on the inner zone L∈[1.4,2] where reliable in situ measurements were lacking. Such statistics are critically needed for an accurate assessment of the role and relative dominance of each type of wave in the dynamics of the inner radiation belt. While VLF waves seem to propagate mainly in a ducted mode at L∼1.5–3 for Kp<3, they appear to be substantially unducted during more disturbed periods (Kp>3). Hiss waves are generally the m. . .
Date: 04/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 2876 - 2893 DOI: 10.1002/jgra.v119.410.1002/2014JA019886 Available at: http://doi.wiley.com/10.1002/jgra.v119.4http://doi.wiley.com/10.1002/2014JA019886
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Authors: O'Brien T P, Claudepierre S G, Guild T B, Fennell J. F., Turner D. L., et al.
Title: Inner zone and slot electron radial diffusion revisited
Abstract: Using recent data from NASA's Van Allen Probes, we estimate the quiet time radial diffusion coefficients for electrons in the inner radiation belt (L < 3) with energies from ~50 to 750 keV. The observations are consistent with dynamics dominated by pitch angle scattering and radial diffusion. We use a coordinate system in which these two modes of diffusion are separable. Then we integrate phase space density over pitch angle to obtain a “bundle content” that is invariant to pitch angle scattering, except for atmospheric loss. We estimate the effective radial diffusion coefficient from the temporal and radial variation of the bundle content. We show that our diffusion coefficients agree well with previously determined values obtained in the 1960s and 1970s and follow the form one . . .
Date: 07/2016 Publisher: Geophysical Research Letters Pages: 7301 - 7310 DOI: 10.1002/2016GL069749 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL069749/full
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Authors: McCollough J. P., Quinn J. M., Starks M. J., and Johnston W R
Title: Intelligent Sampling of Hazardous Particle Populations in Resource-Constrained Environments
Abstract: Sampling of anomaly-causing space environment drivers is necessary for both real-time operations and satellite design efforts, and optimizing measurement sampling helps minimize resource demands. Relating these measurements to spacecraft anomalies requires the ability to resolve spatial and temporal variability in the energetic charged particle hazard of interest. Here we describe a method for sampling particle fluxes informed by magnetospheric phenomenology so that, along a given trajectory, the variations from both temporal dynamics and spatial structure are adequately captured while minimizing oversampling. We describe the coordinates, sampling method, and specific regions and parameters employed. We compare resulting sampling cadences with data from spacecraft spanning the regions of i. . .
Date: 10/2017 Publisher: Space Weather DOI: 10.1002/2017SW001629 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017SW001629/full
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Authors: Su Zhenpeng, Zhu Hui, Xiao Fuliang, Zheng Huinan, Wang Yuming, et al.
Title: Intense duskside lower band chorus waves observed by Van Allen Probes: Generation and potential acceleration effect on radiation belt electrons
Abstract: Local acceleration driven by whistler mode chorus waves largely accounts for the enhancement of radiation belt relativistic electron fluxes, whose favored region is usually considered to be the plasmatrough with magnetic local time approximately from midnight through dawn to noon. On 2 October 2013, the Van Allen Probes recorded a rarely reported event of intense duskside lower band chorus waves (with power spectral density up to 10−3nT2/Hz) in the low-latitude region outside of L=5. Such chorus waves are found to be generated by the substorm-injected anisotropic suprathermal electrons and have a potentially strong acceleration effect on the radiation belt energetic electrons. This event study demonstrates the possibility of broader spatial regions with effective electron acceleration by. . .
Date: 06/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 4266 - 4273 DOI: 10.1002/jgra.v119.610.1002/2014JA019919 Available at: http://doi.wiley.com/10.1002/jgra.v119.6http://doi.wiley.com/10.1002/2014JA019919
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Authors: Gao Zhonglei, Su Zhenpeng, Zhu Hui, Xiao Fuliang, Zheng Huinan, et al.
Title: Intense low-frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons
Abstract: 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 0.1–0.8 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 exhibited hiss-like signatures most of the time. The low-frequency chorus can produce the rapid loss of low-energy (∼0.1 MeV) electrons, different from the normal chorus. For high-energy (≥0.5 MeV) electrons, the low-frequency chorus can yield comparable momentum diffusion to tha. . .
Date: 02/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL067687 Available at: http://doi.wiley.com/10.1002/2016GL067687
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Authors: Hao Y. X., Zong Q.-G., Wang Y. F., Zhou X.-Z., Zhang Hui, et al.
Title: Interactions of energetic electrons with ULF waves triggered by interplanetary shock: Van Allen Probes observations in the magnetotail
Abstract: We present in situ observations of a shock-induced substorm-like event on 13 April 2013 observed by the newly launched Van Allen twin probes. Substorm-like electron injections with energy of 30–500 keV were observed in the region from L∼5.2 to 5.5 immediately after the shock arrival (followed by energetic electron drift echoes). Meanwhile, the electron flux was clearly and strongly varying on the ULF wave time scale. It is found that both toroidal and poloidal mode ULF waves with a period of 150 s emerged following the magnetotail magnetic field reconfiguration after the interplanetary (IP) shock passage. The poloidal mode is more intense than the toroidal mode. The 90° phase shift between the poloidal mode Br and Ea suggests the standing poloidal waves in the Northern Hemisphere. F. . .
Date: 10/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020023 Available at: http://doi.wiley.com/10.1002/2014JA020023
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Authors: Skov Tamitha Mulligan, Fennell Joseph F., Roeder James L., Blake Bernard, and Claudepierre Seth G.
Title: Internal Charging Hazards in Near-Earth Space During Solar Cycle 24 Maximum: Van Allen Probes Measurements
Abstract: The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. The MagEIS suite of sensors measures energy spectra and fluxes of charged particles in the space environment. The calculations show that these fluxes result in electron deposition rates high enough to cause internal charging. We use omnidirectional fluxes of electrons and protons to calculate the dose under varying materials and thicknesses of shielding. We show examples of charge deposition rates during the times of nominal and high levels of penetrating fluxes in the inner magnetosphere covering the period from the beginning of 2013 through mid-2014. These charge deposition rates are related . . .
Date: 09/2015 Publisher: IEEE Transactions on Plasma Science Pages: 3070 - 3074 DOI: 10.1109/TPS.2015.2468214 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=7247811http://xplorestaging.ieee.org/ielx7/27/7247791/07247811.pdf?arnumber=7247811
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Authors: Skov Mulligan, Fennell J.F., Roeder J.L., Blake J.B., and Claudepierre S.G.
Title: Internal Charging Hazards in Near-Earth Space during Solar Cycle 24 Maximum: Van Allen Probes Measurements
Abstract: The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. Data from the MagEIS suite of sensors measures energy spectra, fluxes, and yields electron deposition rates that can cause internal charging. We use omni-directional fluxes of electrons and protons to calculate the dose under varying materials and thicknesses of shielding (similar to Fennell et al., 2010). We show examples of charge deposition rates during times of nominal and high levels of penetrating fluxes in the inner magnetosphere covering the period from late 2012 through 2013. These charge deposition rates are related to charging levels quite possibly encountered. . .
Date: 09/2015 Publisher: JPL DOI: 10.1109/TPS.2015.2468214 Available at: http://ieeexplore.ieee.org/document/7247811/?reload=true&arnumber=7247811
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Authors: Qin Murong, Hudson Mary, Li Zhao, Millan Robyn, Shen Xiaochen, et al.
Title: Investigating Loss of Relativistic Electrons Associated With EMIC Waves at Low L Values on 22 June 2015
Abstract: In this study, rapid loss of relativistic radiation belt electrons at low L* values (2.4–3.2) during a strong geomagnetic storm on 22 June 2015 is investigated along with five possible loss mechanisms. Both the particle and wave data are obtained from the Van Allen Probes. Duskside H+ band electromagnetic ion cyclotron (EMIC) waves were observed during a rapid decrease of relativistic electrons with energy above 5.2 MeV occurring outside the plasmasphere during extreme magnetopause compression. Lower He+ composition and enriched O+ composition are found compared to typical values assumed in other studies of cyclotron resonant scattering of relativistic electrons by EMIC waves. Quantitative analysis demonstrates that even with the existence of He+ band EMIC waves, it is the H+ band EMIC w. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025726 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025726
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Authors: Turner D L, O'Brien T. P., Fennell J F, Claudepierre S. G., Blake J. B., et al.
Title: Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt
Abstract: Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from ~50 keV to ~1 MeV, indicating that slow inward radial diffusion is not the dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can e. . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/1999JA900445 Available at: http://onlinelibrary.wiley.com/doi/10.1029/1999JA900445
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Authors: Turner D. L., O'Brien T P, Fennell J. F., Claudepierre S G, Blake J B, et al.
Title: Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt
Abstract: Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L-shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than one day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from ~50 keV to ~1 MeV, indicating that slow inward radial diffusion is not the dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can excee. . .
Date: 12/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023600 Available at: http://doi.wiley.com/10.1002/2016JA023600
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Authors: Li Zan, Millan Robyn M., Hudson Mary K, Woodger Leslie A., Smith David M., et al.
Title: Investigation of EMIC wave scattering as the cause for the BARREL January 17, 2013 relativistic electron precipitation event: a quantitative comparison of simulation with observations
Abstract: Electromagnetic ion cyclotron (EMIC) waves were observed at multiple observatory locations for several hours on 17 January 2013. During the wave activity period, a duskside relativistic electron precipitation (REP) event was observed by one of the BARREL balloons, and was magnetically mapped close to GOES-13. We simulate the relativistic electron pitch-angle diffusion caused by gyroresonant interactions with EMIC waves using wave and particle data measured by multiple instruments on board GOES-13 and the Van Allen Probes. We show that the count rate, the energy distribution and the time variation of the simulated precipitation all agree very well with the balloon observations, suggesting that EMIC wave scattering was likely the cause for the precipitation event. The event reported here is . . .
Date: 12/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062273 Available at: http://doi.wiley.com/10.1002/2014GL062273
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Authors: Qin Murong, Hudson Mary, Kress Brian, Selesnick Richard, Engel Miles, et al.
Title: Investigation of Solar Proton Access into the inner magnetosphere on 11 September 2017
Abstract: In this study, access of solar energetic protons to the inner magnetosphere on 11 September 2017 is investigated by computing the reverse particle trajectories with the Dartmouth geomagnetic cutoff code [Kress et al., 2010]. The maximum and minimum cutoff rigidity at each point along the orbit of Van Allen Probe A is numerically computed by extending the code to calculate cutoff rigidity for particles coming from arbitrary direction. Pulse‐height analyzed (PHA) data has the advantage of providing individual particle energies and effectively excluding background high energy proton contamination. This technique is adopted to study the cutoff locations for solar protons with different energy. The results demonstrate that cutoff latitude is lower for solar protons with higher energy, consist. . .
Date: 04/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026380 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026380
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Authors: Selesnick R. S., Baker D N, Jaynes A. N., Li X, Kanekal S G, et al.
Title: Inward diffusion and loss of radiation belt protons
Abstract: 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 fixed values of the first two adiabatic invariants. It is postulated that these protons were trapped with enhanced efficiency during the 7 March 2012 solar proton event. A model that includes radial diffusion, along with known trapped proton source and loss processes, s. . .
Date: 03/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA022154 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015JA022154/full
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Authors: Ukhorskiy A Y, Sitnov M I, Merkin V. G., Gkioulidou M., and Mitchell D G
Title: Ion acceleration at dipolarization fronts in the inner magnetosphere
Abstract: During geomagnetic storms plasma pressure in the inner magnetosphere is controlled by energetic ions of tens to hundreds of keV. Plasma pressure is the source of global storm time currents, which control the distribution of magnetic field and couple the inner magnetosphere and the ionosphere. Recent analysis showed that the buildup of hot ion population in the inner magnetosphere largely occurs in the form of localized discrete injections associated with sharp dipolarizations of magnetic field, similar to dipolarization fronts in the magnetotail. Because of significant differences between the ambient magnetic field and the dipolarization front properties in the magnetotail and the inner magnetosphere, the physical mechanisms of ion acceleration at dipolarization fronts in these two regions. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023304 Available at: http://doi.wiley.com/10.1002/2016JA023304
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Authors: Min Kyungguk, Denton Richard E, Liu Kaijun, Gary Peter, and Spence Harlan E.
Title: Ion Bernstein instability as a possible source for oxygen ion cyclotron harmonic waves
Abstract: This paper demonstrates that an ion Bernstein instability can be a possible source for recently reported electromagnetic waves with frequencies at or near the singly ionized oxygen ion cyclotron frequency, inline image, and its harmonics. The particle measurements during strong wave activity revealed a relatively high concentration of oxygen ions (∼15%) whose phase space density exhibits a local peak at energy ∼20 keV. Given that the electron plasma-to-cyclotron frequency ratio is inline image, this energy corresponds to the particle speed inline image, where vA is the oxygen Alfvén speed. Using the observational key plasma parameters, a simplified ion velocity distribution is constructed, where the local peak in the oxygen ion velocity distribution is represented by an isotropic s. . .
Date: 05/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA023979 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA023979/full
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Authors: Ma Q, Li W, Yue C., Thorne R M, Bortnik J, et al.
Title: Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth's Inner Magnetosphere
Abstract: Electromagnetic ion cyclotron (EMIC) waves and magnetosonic waves are commonly observed in the Earth's magnetosphere associated with enhanced ring current activity. Using wave and ion measurements from the Van Allen Probes, we identify clear correlations between the hydrogen‐ and helium‐band EMIC waves with the enhancement of trapped helium and oxygen ion fluxes, respectively. We calculate the diffusion coefficients of different ion species using quasi‐linear theory to understand the effects of resonant scattering by EMIC waves. Our calculations indicate that EMIC waves can cause pitch angle scattering loss of several keV to hundreds of keV ions, and heating of tens of eV to several keV helium and oxygen ions by hydrogen‐ and helium‐band EMIC waves, respectively. Moreover, we fou. . .
Date: 06/2019 Publisher: Geophysical Research Letters Pages: 6258 - 6267 DOI: 10.1029/2019GL083513 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083513
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Authors: Remya B., Sibeck D G, Halford A J, Murphy K. R., Reeves G D, et al.
Title: Ion Injection Triggered EMIC Waves in the Earth's Magnetosphere
Abstract: We present Van Allen Probe observations of electromagnetic ion cyclotron (EMIC) waves triggered solely due to individual substorm‐injected ions in the absence of storms or compressions of the magnetosphere during 9 August 2015. The time at which the injected ions are observed directly corresponds to the onset of EMIC waves at the location of Van Allen Probe A (L = 5.5 and 18:06 magnetic local time). The injection was also seen at geosynchronous orbit by the Geostationary Operational Environmental Satellite and Los Alamos National Laboratory spacecraft, and the westward(eastward) drift of ions(electrons) was monitored by Los Alamos National Laboratory spacecraft at different local times. The azimuthal location of the injection was determined by tracing the injection signatures backward in. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025354 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025354
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Authors: Ferradas C. P., Zhang J.-C., Spence H E, Kistler L. M., Larsen B A, et al.
Title: Ion nose spectral structures observed by the Van Allen Probes
Abstract: We present a statistical study of nose-like structures observed in energetic hydrogen, helium, and oxygen ions near the inner edge of the plasma sheet. Nose structures are spectral features named after the characteristic shapes of energy bands or gaps in the energy-time spectrograms of in situ measured ion fluxes. Using 22 months of observations from the Helium Oxygen Proton Electron (HOPE) instrument onboard Van Allen Probe A, we determine the number of noses observed, and the minimum L-shell reached and energy of each nose on each pass through the inner magnetosphere. We find that multiple noses occur more frequently in heavy ions than in H+, and are most often observed during quiet times. The heavy-ion noses penetrate to lower L shells than H+ noses and there is an energy-magnetic loc. . .
Date: 11/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022942 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022942/full
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Authors: Ukhorskiy A Y, Sorathia K. A., Merkin V. G., Sitnov M I, Mitchell D G, et al.
Title: Ion Trapping and Acceleration at Dipolarization Fronts: High-Resolution MHD/Test-Particle Simulations
Abstract: Much of plasma heating and transport from the magnetotail into the inner magnetosphere occurs in the form of mesoscale discrete injections associated with sharp dipolarizations of magnetic field (dipolarization fronts). In this paper we investigate the role of magnetic trapping in acceleration and transport of the plasmasheet ions into the ring current. For this purpose we use high‐resolution global MHD and three‐dimensional test‐particle simulations. It is shown that trapping, produced by sharp magnetic field gradients at the interface between dipolarizations and the ambient plasma, affect plasmasheet protons with energies above approximately 10 keV, enabling their transport across more than 10 Earth radii and acceleration by a factor of 10. Our estimates show that trapping is impor. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025370 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025370
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Authors: Baker D N, Hoxie V C, Jaynes A., Kale A., Kanekal S G, et al.
Title: James Van Allen and His Namesake NASA Mission
Abstract: In many ways, James A. Van Allen defined and “invented” modern space research. His example showed the way for government-university partners to pursue basic research that also served important national and international goals. He was a tireless advocate for space exploration and for the role of space science in the spectrum of national priorities.
Date: 12/2013 Publisher: Eos, Transactions American Geophysical Union Pages: 469 - 470 DOI: 10.1002/eost.v94.4910.1002/2013EO490001 Available at: http://doi.wiley.com/10.1002/eost.v94.49http://doi.wiley.com/10.1002/2013EO490001
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Authors: Mauk Barry H., Sibeck David G., and Kessel Ramona L.
Title: Journal Special Collection Explores Early Results From the Van Allen Probes Mission
Abstract: The processes governing the charged particle populations in the radiation belts encircling Earth have been the subject of intense interest and increasing concern since their discovery by James Van Allen and his team more than 50 years ago [Baker et al., 2013]. Intense interest continues because we still do not know how the various processes work in concert to enhance, remove, and transport particle radiation. Concern is ongoing because the Van Allen radiation belts pose hazards to astronauts and our ever-growing fleet of spacecraft with increasingly sensitive components.
Date: 04/2014 Publisher: Eos, Transactions American Geophysical Union Pages: 112 - 112 DOI: 10.1002/eost.v95.1310.1002/2014EO130007 Available at: http://doi.wiley.com/10.1002/eost.v95.13http://doi.wiley.com/10.1002/2014EO130007
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Authors: Malaspina David M., Claudepierre Seth G., Takahashi Kazue, Jaynes Allison N., Elkington Scot R, et al.
Title: Kinetic Alfvén Waves and Particle Response Associated with a Shock-Induced, Global ULF Perturbation of the Terrestrial Magnetosphere
Abstract: On 2 October 2013, the arrival of an interplanetary shock compressed the Earth's magnetosphere and triggered a global ULF (ultra low frequency) oscillation. The Van Allen Probe B spacecraft observed this large-amplitude ULF wave in situ with both magnetic and electric field data. Broadband waves up to approximately 100 Hz were observed in conjunction with, and modulated by, this ULF wave. Detailed analysis of fields and particle data reveals that these broadband waves are Doppler-shifted kinetic Alfvén waves. This event suggests that magnetospheric compression by interplanetary shocks can induce abrupt generation of kinetic Alfvén waves over large portions of the inner magnetosphere, potentially driving previously unconsidered wave-particle interactions throughout the inner magnetosphere. . .
Date: 11/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL065935 Available at: http://doi.wiley.com/10.1002/2015GL065935http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL065935
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Authors: Mazur J E, O'Brien T P, Looper M D, and Blake J B
Title: Large anisotropies of >60 MeV protons throughout the inner belt observed with the Van Allen Probes mission
Abstract: We report large directional anisotropies of >60 MeV protons using instrumentation on the Van Allen Probes. The combination of a spinning satellite and measurements from the Relativistic Proton Spectrometer instruments that are insensitive to protons outside the instrument field of view together yield a new look at proton radial gradients. The relatively large proton gyroradius at 60 MeV couples with the radial gradients to produce large (maximum ~10:1) flux anisotropies depending on (i) whether the proton guiding center was above or below the Van Allen Probes spacecraft and (ii) the sign of the local flux gradient. In addition to these newly measured anisotropies, below ~2000 km we report a new effect of systematically changing minimum altitude on some proton drift shells that furthe. . .
Date: 06/2014 Publisher: Geophysical Research Letters Pages: 3738 - 3743 DOI: 10.1002/grl.v41.1110.1002/2014GL060029 Available at: http://doi.wiley.com/10.1002/grl.v41.11http://doi.wiley.com/10.1002/2014GL060029
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Authors: Califf S., Li X, Wolf R. A., Zhao H., Jaynes A. N., et al.
Title: Large-amplitude electric fields in the inner magnetosphere: Van Allen Probes observations of subauroral polarization streams
Abstract: The subauroral polarization stream (SAPS) is an important magnetosphere-ionosphere (MI) coupling phenomenon that impacts a range of particle populations in the inner magnetosphere. SAPS studies often emphasize ionospheric signatures of fast westward flows, but the equatorial magnetosphere is also affected through strong radial electric fields in the dusk sector. This study focuses on a period of steady southward interplanetary magnetic field (IMF) during the 29 June 2013 geomagnetic storm where the Van Allen Probes observe a region of intense electric fields near the plasmapause over multiple consecutive outbound duskside passes. We show that the large-amplitude electric fields near the equatorial plane are consistent with SAPS by investigating the relationship between plasma sheet ion and. . .
Date: 05/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA022252 Available at: http://doi.wiley.com/10.1002/2015JA022252
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Authors: Su Zhenpeng, Liu Nigang, Zheng Huinan, Wang Yuming, and Wang Shui
Title: Large-Amplitude Extremely Low Frequency Hiss Waves in Plasmaspheric Plumes
Abstract: N/A
Date: 01/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076754 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017GL076754/full
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Authors: Motoba T., Takahashi K., Ukhorskiy A., Gkioulidou M., Mitchell D G, et al.
Title: Link between pre-midnight second harmonic poloidal waves and auroral undulations: Conjugate observations with a Van Allen Probes spacecraft and a THEMIS all-sky imager
Abstract: We report, for the first time, an auroral undulation event on 1 May 2013 observed by an all-sky imager (ASI) at Athabasca (L = 4.6), Canada, for which in situ field and particle measurements in the conjugate magnetosphere were available from a Van Allen Probes spacecraft. The ASI observed a train of auroral undulation structures emerging spontaneously in the pre-midnight subauroral ionosphere, during the growth phase of a substorm. The undulations had an azimuthal wavelength of ~180 km and propagated westward at a speed of 3–4 km s−1. The successive passage over an observing point yielded quasi-periodic oscillations in diffuse auroral emissions with a period of ~40 s. The azimuthal wave number m of the auroral luminosity oscillations was found to be m ~ −103. During the event the spa. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020863 Available at: http://doi.wiley.com/10.1002/2014JA020863
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Authors: Smith Evan J., Butler Michael H., Fretz Kristin, and Wilhelm Benjamin
Title: Lithium Ion Battery Fault Management on the Van Allen Probes
Abstract: The Van Allen Probes (formerly known as the Radiation Belt Storm Probes or RBSP) mission launched on 30 August 2012 as part of NASA’s Living With a Star (LWS) Program. The ultimate goal of the mission is to understand how populations of relativistic electrons and penetrating ions in the Earth’s Van Allen Radiation Belts are affected by the Sun. The mission consists of two nearly identical observatories orbiting in highly-elliptical Earth orbits. The two satellite system allows for the study of the spatial and temporal effects the Sun has on the Earth’s radiation belts. Each observatory is equipped with a suite of instruments designed to continuously study ions, electrons and the local magnetic and electric fields. A brief overview of the Van Allen Probe mission is pre. . .
Date: 09/2013 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/6.2013-5526 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2013-5526
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Authors: Ripoll J.‐F., Farges T., Lay E. H., and Cunningham G. S.
Title: Local and Statistical Maps of Lightning‐Generated Wave Power Density Estimated at the Van Allen Probes Footprints From the World‐Wide Lightning Location Network Database
Abstract: We propose a new method that uses the World‐Wide Lightning Location Network (WWLLN) to estimate both the local and the drift lightning power density at the Van Allen Probes footprints during 4.3 years (~2 × 108 strokes.). The ratio of the drift power density to the local power density defines a time‐resolved WWLLN‐based model of lightning‐generated wave (LGW) power density ratio, RWWLLN. RWWLLNis computed every ~34 s. This ratio multiplied by the time‐resolved LGW intensity measured by the Probes allows direct computation of pitch angle diffusion coefficients used in radiation belt codes. Statistical analysis shows the median power density ratio is urn:x-wiley:00948276:media:grl58808:grl58808-math-0001 over the Americas. Elsewhere, urn:x-wiley:00948276:media:grl58808:grl58808-ma. . .
Date: 03/2019 Publisher: Geophysical Research Letters Pages: 4122 - 4133 DOI: 10.1029/2018GL081146 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL081146
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Authors: He Zhaoguo, Chen Lunjin, Liu Xu, Zhu Hui, Liu Si, et al.
Title: Local Generation of High-Frequency Plasmaspheric Hiss Observed by Van Allen Probes
Abstract: The generation of a high‐frequency plasmaspheric hiss (HFPH) wave observed by Van Allen Probes is studied in this letter for the first time. The wave has a moderate power spectral density (∼10−6 nT2/Hz), with a frequency range extended from 2 to 10 kHz. The correlated observations of waves and particles indicate that HFPH is associated with the enhancement of electron flux during the substorm on 6 January 2014. Calculations of the wave linear growth rate driven by the fitted electron phase space density show that the electron distribution after the substorm onset is efficient for the HFPH generation. The energy of the contributing electrons is about 1–2 keV, which is consistent with the observation. These results support that the observed HFPH is likely to be generated locally insi. . .
Date: 01/2019 Publisher: Geophysical Research Letters Pages: 1141 - 1148 DOI: 10.1029/2018GL081578 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL081578
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Authors: Sarno-Smith Lois K., Liemohn Michael W., Skoug Ruth M., Larsen Brian A., Moldwin Mark B., et al.
Title: Local time variations of high-energy plasmaspheric ion pitch angle distributions
Abstract: Recent observations from the Van Allen Probes Helium Oxygen Proton Electron (HOPE) instrument revealed a persistent depletion in the 1–10 eV ion population in the postmidnight sector during quiet times in the 2 < L < 3 region. This study explores the source of this ion depletion by developing an algorithm to classify 26 months of pitch angle distributions measured by the HOPE instrument. We correct the HOPE low energy fluxes for spacecraft potential using measurements from the Electric Field and Waves (EFW) instrument. A high percentage of low count pitch angle distributions is found in the postmidnight sector coupled with a low percentage of ion distributions peaked perpendicular to the field line. A peak in loss cone distributions in the dusk sector is also observed. These results char. . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA022301 Available at: http://doi.wiley.com/10.1002/2015JA022301
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Authors: Tetrick S. S., Engebretson M. J., Posch J. L., Olson C. N., Smith C W, et al.
Title: Location of intense electromagnetic ion cyclotron (EMIC) wave events relative to the plasmapause: Van Allen Probes observations
Abstract: We have studied the spatial location relative to the plasmapause (PP) of the most intense electromagnetic ion cyclotron (EMIC) waves observed on Van Allen Probes A and B during their first full precession in local time. Most of these waves occurred over an L range of from -1 to +2 RE relative to the PP. Very few events occurred only within 0.1 RE of the PP, and events with a width in L of < 0.2 REoccurred both inside and outside the PP. Wave occurrence was always associated with high densities of ring current ions; plasma density gradients or enhancements were associated with some events but were not dominant factors in determining the sites of wave generation. Storm main and recovery phase events in the dusk sector were often inside the PP, and dayside events during quiet times and co. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023392 Available at: http://doi.wiley.com/10.1002/2016JA023392
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Authors: áhlava J., ěmec F., ík O., šová I., Hospodarskyy G. B., et al.
Title: Longitudinal dependence of whistler mode electromagnetic waves in the Earth's inner magnetosphere
Abstract: We use the measurements performed by the DEMETER (2004‐2010) and the Van Allen Probes (2012‐2016, still operating) spacecraft to investigate the longitudinal dependence of the intensity of whistler mode waves in the Earth's inner magnetosphere. We show that a significant longitudinal dependence is observed inside the plasmasphere on the nightside, primarily in the frequency range 400 Hz–2 kHz. On the other hand, almost no longitudinal dependence is observed on the dayside. The obtained results are compared to the lightning occurrence rate provided by the OTD/LIS mission normalized by a factor accounting for the ionospheric attenuation. The agreement between the two dependencies indicates that lightning generated electromagnetic waves may be responsible for the observed effect, thus s. . .
Date: 07/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025284 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025284
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Authors: é M., Matsuoka A., Kumamoto A., Kasahara Y., Goldstein J, et al.
Title: Longitudinal Structure of Oxygen Torus in the Inner Magnetosphere: Simultaneous Observations by Arase and Van Allen Probe A
Abstract: Simultaneous observations of the magnetic field and plasma waves made by the Arase and Van Allen Probe A satellites at different magnetic local time (MLT) enable us to deduce the longitudinal structure of an oxygen torus for the first time. During 04:00–07:10 UT on 24 April 2017, Arase flew from L = 6.2 to 2.0 in the morning sector and detected an enhancement of the average plasma mass up to ~3.5 amu around L = 4.9–5.2 and MLT = 5.0 hr, implying that the plasma consists of approximately 15% O+ ions. Probe A moved outbound from L = 2.0 to 6.2 in the afternoon sector during 04:10–07:30 UT and observed no clear enhancements in the average plasma mass. For this event, the O+ density enhancement in the inner magnetosphere (i.e., oxygen torus) does not extend over all MLT but is skewed tow. . .
Date: 10/2018 Publisher: Geophysical Research Letters Pages: 10,177 - 10,184 DOI: 10.1029/2018GL080122 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL080122
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Authors: Baker D N, Kanekal S G, Hoxie V C, Henderson M G, Li X, et al.
Title: A Long-Lived Relativistic Electron Storage Ring Embedded in Earth's Outer Van Allen Belt
Abstract: Since their discovery more than 50 years ago, Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unc. . .
Date: 04/2013 Publisher: Science Pages: 186-190 DOI: 10.1126/science.1233518 Available at: http://www.sciencemag.org/content/340/6129/186
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Authors: Ren Jie, Zong Q. G., Miyoshi Y, Zhou X. Z., Wang Y. F., et al.
Title: Low-energy (< 200 eV) electron acceleration by ULF waves in the plasmaspheric boundary layer: Van Allen Probes observation
Abstract: We report observational evidence of cold plamsmaspheric electron (< 200 eV) acceleration by ultra-low-frequency (ULF) waves in the plasmaspheric boundary layer on 10 September 2015. Strongly enhanced cold electron fluxes in the energy spectrogram were observed along with second harmonic mode waves with a period of about 1 minute which lasted several hours during two consecutive Van Allen Probe B orbits. Cold electron (<200 eV) and energetic proton (10-20 keV) bi-directional pitch angle signatures observed during the event are suggestive of the drift-bounce resonance mechanism. The correlation between enhanced energy fluxes and ULF waves leads to the conclusions that plasmaspheric dynamics is strongly affected by ULF waves. Van Allen Probe A and B, GOES 13, GOES 15 and MMS 1 observations su. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024316 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024316/full
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Authors: Gkioulidou Matina, Ohtani S, Ukhorskiy A Y, Mitchell D G, Takahashi K., et al.
Title: Low-Energy (+ Ion Outflow Directly Into the Inner Magnetosphere: Van Allen Probes Observations
Abstract: The heavy ion component of the low‐energy (eV to hundreds of eV) ion population in the inner magnetosphere, also known as the O+ torus, is a crucial population for various aspects of magnetospheric dynamics. Yet even though its existence has been known since the 1980s, its formation remains an open question. We present a comprehensive study of a low‐energy (Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 405 - 419 DOI: 10.1029/2018JA025862 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025862
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Authors: Khazanov G. V., Boardsen S., Krivorutsky E. N., Engebretson M. J., Sibeck D., et al.
Title: Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B
Abstract: We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions' polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth . . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics Pages: 449 - 463 DOI: 10.1002/2016JA022814 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022814/full
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Authors: Khazanov G. V., Boardsen S., Krivorutsky E. N., Engebretson M. J., Sibeck D., et al.
Title: Lower hybrid frequency range waves generated by ion polarization drift due to electromagnetic ion cyclotron waves: Analysis of an event observed by the Van Allen Probe B
Abstract: We analyze a wave event that occurred near noon between 07:03 and 07:08 UT on 23 February 2014 detected by the Van Allen Probes B spacecraft, where waves in the lower hybrid frequency range (LHFR) and electromagnetic ion cyclotron (EMIC) waves are observed to be highly correlated, with Pearson correlation coefficient of ~0.86. We assume that the correlation is the result of LHFR wave generation by the ions' polarization drift in the electric field of the EMIC waves. To check this assumption the drift velocities of electrons and H+, He+, and O+ ions in the measured EMIC wave electric field were modeled. Then the LHFR wave linear instantaneous growth rates for plasma with these changing drift velocities and different plasma compositions were calculated. The time distribution of these growth . . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022814 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022814
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Authors: Posch J. L, Engebretson M. J., Olson C. N., Thaller S. A., Breneman A. W., et al.
Title: Low-harmonic magnetosonic waves observed by the Van Allen Probes
Abstract: Purely compressional electromagnetic waves (fast magnetosonic waves), generated at multiple harmonics of the local proton gyrofrequency, have been observed by various types of satellite instruments (fluxgate and search coil magnetometers and electric field sensors), but most recent studies have used data from search coil sensors, and many have been restricted to high harmonics. We report here on a survey of low-harmonic waves, based on electric and magnetic field data from the EFW double probe and EMFISIS fluxgate magnetometer instruments, respectively, on the Van Allen Probes spacecraft during its first full precession through all local times, from October 1, 2012 through July 13, 2014. These waves were observed both inside and outside the plasmapause (PP), at L shells from 2.4 to ~6 (the. . .
Date: 07/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021179 Available at: http://doi.wiley.com/10.1002/2015JA021179
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Authors: Lejosne ène, and Mozer F S
Title: Magnetic activity dependence of the electric drift below L=3
Abstract: More than two years of magnetic and electric field measurements by the Van Allen Probes are analyzed with the objective of determining the average effects of magnetic activity on the electric drift below L=3. The study finds that an increase in magnetospheric convection leads to a decrease in the magnitude of the azimuthal component of the electric drift, especially in the night‐side. The amplitude of the slowdown is a function of L, local time MLT, and Kp, in a pattern consistent with the storm‐time dynamics of the ionosphere and thermosphere. To a lesser extent, magnetic activity also alters the average radial component of the electric drift below L=3. A global picture for the average variations of the electric drift with Kp is provided as a function of L and MLT. It is the first tim. . .
Date: 04/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL077873 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077873
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Authors: Blake J B, Carranza P A, Claudepierre S G, Clemmons J H, Crain W R, et al.
Title: The Magnetic Electron Ion Spectrometer (MagEIS) Instruments Aboard the Radiation Belt Storm Probes (RBSP) Spacecraft
Abstract: This paper describes the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the RBSP spacecraft from an instrumentation and engineering point of view. There are four magnetic spectrometers aboard each of the two spacecraft, one low-energy unit (20–240 keV), two medium-energy units (80–1200 keV), and a high-energy unit (800–4800 keV). The high unit also contains a proton telescope (55 keV–20 MeV). The magnetic spectrometers focus electrons within a selected energy pass band upon a focal plane of several silicon detectors where pulse-height analysis is used to determine if the energy of the incident electron is appropriate for the electron momentum selected by the magnet. Thus each event is a two-parameter analysis, an approach leading to a greatly reduced background. . . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 383-421 DOI: 10.1007/s11214-013-9991-8
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Authors: Vasko I. Y., Agapitov O. V., Mozer F, Artemyev A. V., and Jovanovic D.
Title: Magnetic field depression within electron holes
Abstract: We analyze electron holes that are spikes of the electrostatic field (up to 500 mV/m) observed by Van Allen Probes in the outer radiation belt. The unexpected feature is the magnetic field depression of about several tens of picotesla within many of the spikes. The earlier observations showed amplification or negligible perturbations of the magnetic field within the electron holes. We suggest that the observed magnetic field depression is due to the diamagnetic current of hot and highly anisotropic population of electrons trapped within the electron holes. The required trapped population should have a density up to 65% of the background plasma density, a temperature up to several keV, and a temperature anisotropy T⊥/T∥∼2. We argue that the observed electron holes could be generated. . .
Date: 04/2015 Publisher: Geophysical Research Letters Pages: 2123 - 2129 DOI: 10.1002/2015GL063370 Available at: http://doi.wiley.com/10.1002/2015GL063370
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Authors: Paral J., Hudson M K, Kress B T, Wiltberger M. J., Wygant J R, et al.
Title: Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013
Abstract: Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on th. . .
Date: 08/2015 Publisher: Annales Geophysicae Pages: 1037 - 1050 DOI: 10.5194/angeo-33-1037-2015 Available at: http://www.ann-geophys.net/33/1037/2015/angeo-33-1037-2015.pdf
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Authors: Liu Nigang, Su Zhenpeng, Zheng Huinan, Wang Yuming, and Wang Shui
Title: Magnetosonic harmonic falling and rising frequency emissions potentially generated by nonlinear wave-wave interactions in the Van Allen radiation belts
Abstract: Magnetosonic waves play a potentially important role in the complex evolution of the radiation belt electrons. These waves typically appear as discrete emission lines along the proton gyrofrequency harmonics, consistent with the prediction of the local Bernstein mode instability of hot proton ring distributions. Magnetosonic waves are nearly dispersionless particularly at low harmonics and therefore have the roughly unchanged frequency‐time structures during the propagation. On the basis of Van Allen Probes observations, we here present the first report of magnetosonic harmonic falling and rising frequency emissions. They lasted for up to 2 h and occurred primarily in the dayside plasmatrough following intense substorms. These harmonic emission lines were well spaced by the proton gyrofr. . .
Date: 07/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079232 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079232
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