Biblio

Found 830 results
2016
Authors: Li Jinxing, Ni Binbin, Ma Qianli, Xie Lun, Pu Zuyin, et al.
Title: Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance
Abstract: 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°, 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 resolved. By analyzing the particle and wave data collected by the Van Allen Probes during a geomagnetic storm, we combine test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation. . .
Date: 04/2016 Publisher: Geophysical Research Letters Pages: n/a - n/a DOI: 10.1002/2016GL067853 Available at: http://doi.wiley.com/10.1002/2016GL067853http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2016GL067853
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Authors: Su Yi-Jiun, Selesnick Richard S., and Blake J B
Title: Formation of the inner electron radiation belt by enhanced large-scale electric fields
Abstract: A two-dimensional bounce-averaged test particle code was developed to examine trapped electron trajectories during geomagnetic storms with the assumption of conservation of the first and second adiabatic invariants. The March 2013 storm was selected as an example because the geomagnetic activity Kp index sharply increased from 2 + to 7− at 6:00 UT on 17 March. Electron measurements with energies between 37 and 460 keV from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard Van Allen Probes (VAP) are used as initial conditions prior to the storm onset and served to validate test particle simulations during the storm. Simulation results help to interpret the observed electron injection as nondiffusive radial transport over a short distance in the inner belt and slot. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022881 Available at: http://doi.wiley.com/10.1002/2016JA022881
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Authors: Morley Steven K., Sullivan John P., Henderson Michael G., Blake Bernard, and Baker Daniel N
Title: The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data
Abstract: Energetic electron observations in Earth's radiation belts are typically sparse and multi-point studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross-calibration into two parts – one that removes any spectral assumptions from the CXD flux calculation, and one that compares the energy spectra – we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra we use a combination of four distributions that, together. . .
Date: 02/2016 Publisher: Space Weather DOI: 10.1002/2015SW001339 Available at: http://doi.wiley.com/10.1002/2015SW001339
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Authors: Li Zhao, Hudson Mary, Paral Jan, Wiltberger Michael, and Turner Drew
Title: Global ULF wave analysis of radial diffusion coefficients using a global MHD model for the 17 March 2015 storm
Abstract: The 17–18 March 2015 storm is the largest geomagnetic storm in the Van Allen Probes era to date. The Lyon-Fedder-Mobarry global MHD model has been run for this event using ARTEMIS data as solar wind input. The ULF wave power spectral density of the azimuthal electric field and compressional magnetic field is analyzed in the 0.5–8.3 mHz range. The lowest three azimuthal modes account for 70% of the total power during quiet times. However, during high activity, they are not exclusively dominant. The calculation of the radial diffusion coefficient is presented. We conclude that the electric field radial diffusion coefficient is dominant over the magnetic field coefficient by one to two orders of magnitude. This result contrasts with the dominant magnetic field diffusion coefficient used i. . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022508 Available at: http://doi.wiley.com/10.1002/2016JA022508
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Authors: Sarno-Smith Lois K., Liemohn Michael W., Skoug Ruth M., Santolík Ondrej, Morley Steven K., et al.
Title: Hiss or Equatorial Noise? Ambiguities in Analyzing Suprathermal Ion Plasma Wave Resonance
Abstract: Previous studies have shown that low energy ion heating occurs in the magnetosphere due to strong equatorial noise emission. Observations from the Van Allen Probes Helium Oxygen Proton Electron (HOPE) instrument recently determined there was a depletion in the 1-10 eV ion population in the post-midnight sector of Earth during quiet times at L < 3. The diurnal variation of equatorially mirroring 1-10 eV H+ ions between 2 < L < 3 is connected with similar diurnal variation in the electric field component of plasma waves ranging between 150 and 600 Hz. Measurements from the Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) data set are used to analyze waves of this frequency in near-Earth space. However, when we examine the polarization of the wave. . .
Date: 09/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022975 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022975/abstract
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Authors: Mann Ian R., and Ozeke Louis G.
Title: How quickly, how deeply, and how strongly can dynamical outer boundary conditions impact Van Allen radiation belt morphology?
Abstract: Here we examine the speed, strength, and depth of the coupling between dynamical variations of ultrarelativistic electron flux at the outer boundary and that in the heart of the outer radiation belt. Using ULF wave radial diffusion as an exemplar, we show how changing boundary conditions can completely change belt morphology even under conditions of identical wave power. In the case of ULF wave radial diffusion, the temporal dynamics of a new source population or a sink of electron flux at the outer plasma sheet boundary can generate a completely opposite response which reaches deep into the belt under identical ULF wave conditions. Very significantly, here we show that such coupling can occur on timescales much faster than previously thought. We show that even on timescales ~1 h, change. . .
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 5553 - 5558 DOI: 10.1002/jgra.v121.610.1002/2016JA022647 Available at: http://doi.wiley.com/10.1002/2016JA022647
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Authors: Yuan Zhigang, Yu Xiongdong, Wang Dedong, Huang Shiyong, Li Haimeng, et al.
Title: In situ evidence of the modification of the parallel propagation of EMIC waves by heated He + ions
Abstract: With observations of the Van Allen Probe B, we report in situ evidence of the modification of the parallel propagating electromagnetic ion cyclotron (EMIC) waves by heated He+ ions. In the outer boundary of the plasmasphere, accompanied with the He+ ion heating, the frequency bands of H+ and He+ for EMIC waves merged into each other, leading to the disappearance of a usual stop band between the gyrofrequency of He+ ions (ΩHe+) and the H+ cutoff frequency (ωH+co) in the cold plasma. Moreover, the dispersion relation for EMIC waves theoretically calculated with the observed plasma parameters also demonstrates that EMIC waves can indeed parallel propagate across ΩHe+. Therefore, the paper provides an in situ evidence of the modification of the parallel propagation of EMIC waves by heated H. . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022573 Available at: http://doi.wiley.com/10.1002/2016JA022573
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Authors: Paulson K. W., Smith C W, Lessard M. R., Torbert R B, Kletzing C A, et al.
Title: In situ statistical observations of Pc1 pearl pulsations and unstructured EMIC waves by the Van Allen Probes
Abstract: We present here the first in situ statistical survey of structured Pc1 pearl pulsations compared with unstructured electromagnetic ion cyclotron (EMIC) waves observed by the Van Allen Probes spacecraft. This data set was compiled from observations spanning 8 September 2012 through 31 August 2015 and comprises over 1630 h of total EMIC wave activity, of which 291 h exhibited pearl structure. Additionally, we have identified 29 wave events demonstrating periodically oscillating wave packets, mostly about the magnetic equator, indicated by the reversal of Poynting flux along the background magnetic field. We have found several stark differences between Pc1 pearl pulsations and unstructured EMIC waves. While unstructured EMIC waves demonstrate the predicted behavior of a higher occurrence acro. . .
Date: 12/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023160 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023160/full
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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: 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: 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: 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: 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: 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: 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: 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: Turunen Esa, Kero Antti, Verronen Pekka T., Miyoshi Yoshizumi, Oyama Shin-Ichiro, et al.
Title: Mesospheric ozone destruction by high-energy electron precipitation associated with pulsating aurora
Abstract: Energetic particle precipitation into the upper atmosphere creates excess amounts of odd nitrogen and odd hydrogen. These destroy mesospheric and upper stratospheric ozone in catalytic reaction chains, either in situ at the altitude of the energy deposition or indirectly due to transport to other altitudes and latitudes. Recent statistical analysis of satellite data on mesospheric ozone reveals that the variations during energetic electron precipitation from Earth's radiation belts can be tens of percent. Here we report model calculations of ozone destruction due to a single event of pulsating aurora early in the morning on 17 November 2012. The presence of high-energy component in the precipitating electron flux (>200 keV) was detected as ionization down to 68 km altitude, by the VHF inco. . .
Date: 10/2016 Publisher: Journal of Geophysical Research: Atmospheres Pages: 11,852 - 11,861 DOI: 10.1002/2016JD025015 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JD025015/full
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Authors: Xia Zhiyang, Chen Lunjin, Dai Lei, Claudepierre Seth G., Chan Anthony A, et al.
Title: Modulation of chorus intensity by ULF waves deep in the inner magnetosphere
Abstract: Previous studies have shown that chorus wave intensity can be modulated by Pc4-Pc5 compressional ULF waves. In this study, we present Van Allen Probes observation of ULF wave modulating chorus wave intensity, which occurred deep in the magnetosphere. The ULF wave shows fundamental poloidal mode signature and mirror mode compressional nature. The observed ULF wave can modulate not only the chorus wave intensity but also the distribution of both protons and electrons. Linear growth rate analysis shows consistence with observed chorus intensity variation at low frequency (f <∼ 0.3fce), but cannot account for the observed higher-frequency chorus waves, including the upper band chorus waves. This suggests the chorus waves at higher-frequency ranges require nonlinear mechanisms. In addition, w. . .
Date: 09/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL070280 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2016GL070280/full
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Authors: Reiff P. H., Daou A. G., Sazykin S. Y., Nakamura R, Hairston M. R., et al.
Title: Multispacecraft Observations and Modeling of the June 22/23, 2015 Geomagnetic Storm
Abstract: The magnetic storm of June 22-23, 2015 was one of the largest in the current solar cycle. We present in situ observations from the Magnetospheric Multiscale Mission (MMS) and the Van Allen Probes (VAP) in the magnetotail, field-aligned currents from AMPERE, and ionospheric flow data from DMSP. Our real-time space weather alert system sent out a “red alert”, correctly predicting Kp indices greater than 8. We show strong outflow of ionospheric Oxygen, dipolarizations in the MMS magnetometer data, and dropouts in the particle fluxes seen by the MMS FPI instrument suite. At ionospheric altitudes, the AMPERE data show highly variable currents exceeding 20 MA. We present numerical simulations with the BATS-R-US global magnetohydrodynamic (MHD) model linked with the Rice Convection Model (RCM. . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL069154 Available at: http://doi.wiley.com/10.1002/2016GL069154
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Authors: Mozer F S, Artemyev A., Agapitov O. V., Mourenas D., and Vasko I.
Title: Near-Relativistic Electron Acceleration by Landau Trapping in Time Domain Structures
Abstract: Data from the Van Allen Probes have provided the first extensive evidence of nonlinear (as opposed to quasi-linear) wave-particle interactions in space with the associated rapid (less than a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric field of time domain structures (TDSs) traveling at high speeds (~20,000 km/s). This observational evidence is supported by simulations and discussion of the source and spatial extent of the fast TDS. This result indicates the possibility that the electrostatic fields in TDS may generate the electron seed population for cyclotron resonance interaction with chorus waves to make higher-energy electrons.
Date: 01/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL067316 Available at: http://doi.wiley.com/10.1002/2015GL067316
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Authors: Souza V. M., Vieira L. E. A., Medeiros C., Da Silva L. A., Alves L. R., et al.
Title: A neural network approach for identifying particle pitch angle distributions in Van Allen Probes data
Abstract: Analysis of particle pitch angle distributions (PADs) has been used as a means to comprehend a multitude of different physical mechanisms that lead to flux variations in the Van Allen belts and also to particle precipitation into the upper atmosphere. In this work we developed a neural network-based data clustering methodology that automatically identifies distinct PAD types in an unsupervised way using particle flux data. One can promptly identify and locate three well-known PAD types in both time and radial distance, namely, 90° peaked, butterfly, and flattop distributions. In order to illustrate the applicability of our methodology, we used relativistic electron flux data from the whole month of November 2014, acquired from the Relativistic Electron-Proton Telescope instrument on board. . .
Date: 04/2016 Publisher: Space Weather Pages: n/a - n/a DOI: 10.1002/2015SW001349 Available at: http://doi.wiley.com/10.1002/2015SW001349http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015SW001349
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Authors: Li W, Santolik O, Bortnik J, Thorne R M, Kletzing C A, et al.
Title: New Chorus Wave Properties Near the Equator from Van Allen Probes Wave Observations
Abstract: The chorus wave properties are evaluated using Van Allen Probes data in the Earth's equatorial magnetosphere. Two distinct modes of lower band chorus are identified: a quasi-parallel mode and a quasi-electrostatic mode, whose wave normal direction is close to the resonance cone. Statistical results indicate that the quasi-electrostatic (quasi-parallel) mode preferentially occurs during relatively quiet (disturbed) geomagnetic activity at lower (higher) L shells. Although the magnetic intensity of the quasi-electrostatic mode is considerably weaker than the quasi-parallel mode, their electric intensities are comparable. A newly identified feature of the quasi-electrostatic mode is that its frequency peaks at higher values compared to the quasi-parallel mode that exhibits a broad frequency s. . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL068780 Available at: http://doi.wiley.com/10.1002/2016GL068780
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Authors: Orlova Ksenia, Shprits Yuri, and Spasojevic Maria
Title: New global loss model of energetic and relativistic electrons based on Van Allen Probes measurements
Abstract: Energetic electron observations in Earth's radiation belts are typically sparse and multi-point studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross-calibration into two parts – one that removes any spectral assumptions from the CXD flux calculation, and one that compares the energy spectra – we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra we use a combination of four distributions that, together. . .
Date: 02/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021878 Available at: http://doi.wiley.com/10.1002/2015JA021878
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Authors: Yu Yiqun, Jordanova Vania K., Ridley Aaron J., Albert Jay M, Horne Richard B, et al.
Title: A new ionospheric electron precipitation module coupled with RAM-SCB within the geospace general circulation model
Abstract: Electron precipitation down to the atmosphere due to wave-particle scattering in the magnetosphere contributes significantly to the auroral ionospheric conductivity. In order to obtain the auroral conductivity in global MHD models that are incapable of capturing kinetic physics in the magnetosphere, MHD parameters are often used to estimate electron precipitation flux for the conductivity calculation. Such an MHD approach, however, lacks self-consistency in representing the magnetosphere-ionosphere coupling processes. In this study we improve the coupling processes in global models with a more physical method. We calculate the physics-based electron precipitation from the ring current and map it to the ionospheric altitude for solving the ionospheric electrodynamics. In particular, we use . . .
Date: 09/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022585 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022585/full
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Authors: Tao Dan, Battiston Roberto, Vitale Vincenzo, Burger William J., Lazzizzera Ignazio, et al.
Title: A new method to study the time correlation between Van Allen Belt electrons and earthquakes
Abstract: A new method to study a possible temporal correlation between hundreds of keV Van Allen Belt electrons and strong earthquakes is proposed. It consists in measuring the electrons pitch angle distribution (PAD), searching for PAD disturbances, and studying the time correlation between these PAD disturbances and strong earthquakes, occurring within a defined time window. The method was applied to measurements of energetic electrons, which were performed with the Energetic Particle, Composition, and Thermal Plasma (ECT)-MagEIS detector on board the Van Allen Probes (VAPs) mission and strong continental earthquakes, with magnitude M 5.0 and hypocenter depth 100 km. We report the correlation studies for electrons with energies of about 350 keV, with which a 3.84 standard deviations correlat. . .
Date: 10/2016 Publisher: International Journal of Remote Sensing Pages: 5304 - 5319 DOI: 10.1080/01431161.2016.1239284 Available at: https://www.tandfonline.com/doi/full/10.1080/01431161.2016.1239284
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Authors: Matsui H., Paulson K. W., Torbert R B, Spence H E, Kletzing C A, et al.
Title: Nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012
Abstract: In this study, we investigate the possibility of nonlinearity in chorus waves during a geomagnetic storm on 1 November 2012. The data we use were measured by the Van Allen Probe B. Wave data and plasma sheet electron data are analyzed. Chorus waves were frequently measured in the morning side during the main phase of this storm. Large-amplitude chorus waves were seen of the order of ∼0.6 nT and >7 mV/m, which are similar to or larger than the typical ULF waves. The waves quite often consist of rising tones during the burst sampling. Since the rising tone is known as a signature of nonlinearity, a large portion of the waves are regarded as nonlinear at least during the burst sampling periods. These results underline the importance of nonlinearity in the dynamics of chorus waves. We furthe. . .
Date: 01/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021772 Available at: http://doi.wiley.com/10.1002/2015JA021772
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Authors: Su Zhenpeng, Gao Zhonglei, Zhu Hui, Li Wen, Zheng Huinan, et al.
Title: Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013
Abstract: Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (∼500 keV to several MeV) and equatorial pitch angles (0°≤αe≤180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Our results emphasize the complexity of radiation belt dynamics and the importance of. . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022546 Available at: http://doi.wiley.com/10.1002/2016JA022546
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Authors: Burke W. J., Erickson P. J., Yang J., Foster J., Wygant J, et al.
Title: O + Ion Conic and Plasma Sheet Dynamics Observed by Van Allen Probe Satellites during the 1 June 2013 Magnetic Storm
Abstract: The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring current's “nose structure” into the plasma sheet, the satellites encountered a quasi-periodic sequence of 0.08 - 3 keV O+ ions. Pitch angle distributions of this population consistently peaked nearly anti-parallel to the local magnetic field. We interpret this population as O+ conics originating in the northern ionosphere. Sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over about a half hour build-up phase, O+ energies peaked near 1 keV. During subsequent release phases lasting ~ 20 minutes, O+ energies returned to low-energy starting points. We argu. . .
Date: 05/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021795 Available at: http://doi.wiley.com/10.1002/2015JA021795
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Authors: Artemyev Anton, Agapitov Oleksiy, Mourenas Didier, Krasnoselskikh Vladimir, Shastun Vital, et al.
Title: Oblique Whistler-Mode Waves in the Earth’s Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics
Abstract: In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth’s inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and non-linear generation, propagation, and damping processes. We further examine how such oblique wave populations can be included into both quasi-linear diffusion models and fully nonlinear models of wave-particle interaction. On this basis, we demonstrate that varying amounts of obliq. . .
Date: 04/2016 Publisher: Space Science Reviews Pages: 261 - 355 DOI: 10.1007/s11214-016-0252-5 Available at: https://link.springer.com/article/10.1007/s11214-016-0252-5
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Authors: Aryan Homayon, Sibeck David, Balikhin Michael, Agapitov Oleksiy, and Kletzing Craig
Title: Observation of chorus waves by the Van Allen Probes: Dependence on solar wind parameters and scale size
Abstract: Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not onl. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 7608 - 7621 DOI: 10.1002/jgra.v121.810.1002/2016JA022775 Available at: http://doi.wiley.com/10.1002/2016JA022775
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Authors: Nakamura Satoko, Omura Yoshiharu, Summers Danny, and Kletzing Craig A.
Title: Observational evidence of the nonlinear wave growth theory of plasmaspheric hiss
Abstract: We test the recently developed nonlinear wave growth theory of plasmaspheric hiss against discrete rising tone elements of hiss emissions observed by the Van Allen Probes. From the phase variation of the waveforms processed by bandpass filters, we calculate the instantaneous frequencies and wave amplitudes. We obtain the theoretical relation between the wave amplitude and frequency sweep rates at the observation point by applying the convective growth rates and dispersion factors to the known relation at the equator. By plotting the theoretical relation over scatterplots of the wave amplitudes and the frequency sweep rates for rising tone elements, we find good agreement between the hiss observations and the nonlinear theory. We also find that the duration periods of the hiss elements are . . .
Date: 09/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL070333 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL070333/full
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Authors: Foster J. C., Erickson P. J., Baker D N, Jaynes A. N., Mishin E. V., et al.
Title: Observations of the impenetrable barrier, the plasmapause, and the VLF bubble during the 17 March 2015 storm
Abstract: Van Allen Probes observations during the 17 March 2015 major geomagnetic storm strongly suggest that VLF transmitter-induced waves play an important role in sculpting the earthward extent of outer zone MeV electrons. A magnetically confined bubble of very low frequency (VLF) wave emissions of terrestrial, human-produced origin surrounds the Earth. The outer limit of the VLF bubble closely matches the position of an apparent barrier to the inward extent of multi-MeV radiation belt electrons near 2.8 Earth radii. When the VLF transmitter signals extend beyond the eroded plasmapause, electron loss processes set up near the outer extent of the VLF bubble create an earthward limit to the region of local acceleration near L = 2.8 as MeV electrons are scattered into the atmospheric loss cone.
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 5537 - 5548 DOI: 10.1002/jgra.v121.610.1002/2016JA022509 Available at: http://doi.wiley.com/10.1002/2016JA022509
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Authors: Ni Binbin, Zou Zhengyang, Li Xinlin, Bortnik Jacob, Xie Lun, et al.
Title: Occurrence Characteristics of Outer Zone Relativistic Electron Butterfly Distribution: A Survey of Van Allen Probes REPT Measurements
Abstract: Using Van Allen Probes REPT pitch angle resolved electron flux data from September 2012 to March 2015, we investigate in detail the global occurrence pattern of equatorial (|λ| ≤ 3°) butterfly distribution of outer zone relativistic electrons and its potential correlation with the solar wind dynamic pressure. The statistical results demonstrate that these butterfly distributions occur with the highest occurrence rate ~ 80% at ~ 20 – 04 MLT and L > ~ 5.5 and with the second peak (> ~ 50 %) at ~ 11 – 15 MLT of lower L-shells ~ 4.0. They can also extend to L = 3.5 and to other MLT intervals but with the occurrence rates predominantly < ~25%. It is further shown that outer zone relativistic electron butterfly distributions are likely to peak between . . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL069350 Available at: http://doi.wiley.com/10.1002/2016GL069350
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Authors: Westlake J. H., Cohen I. J., Mauk B H, Anderson B J, Mitchell D G, et al.
Title: The permeability of the magnetopause to a multispecies substorm injection of energetic particles
Abstract: Leakage of ions from the magnetosphere into the magnetosheath remains an important topic in understanding the plasma physics of Earth's magnetopause and the interaction of the solar wind with the magnetosphere. Here using sophisticated instrumentation from two spacecraft (Radiation Belt Storm Probes Ion Composition Experiment on the Van Allen Probes and Energetic Ion Spectrometer on the Magnetospheric Multiscale) spaced uniquely near and outside the dayside magnetopause, we are able to determine the escape mechanisms for large gyroradii oxygen ions and much smaller gyroradii hydrogen and helium ions. The oxygen ions are entrained on the magnetosphere boundary, while the hydrogen and helium ions appear to escape along reconnected field lines. These results have important implications for no. . .
Date: 09/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL070189 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL070189/full
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Authors: Zhang X.-J., Li W, Thorne R M, Angelopoulos V, Ma Q, et al.
Title: Physical mechanism causing rapid changes in ultrarelativistic electron pitch angle distributions right after a shock arrival: Evaluation of an electron dropout event
Abstract: Three mechanisms have been proposed to explain relativistic electron flux depletions (dropouts) in the Earth's outer radiation belt during storm times: adiabatic expansion of electron drift shells due to a decrease in magnetic field strength, magnetopause shadowing and subsequent outward radial diffusion, and precipitation into the atmosphere (driven by EMIC wave scattering). Which mechanism predominates in causing electron dropouts commonly observed in the outer radiation belt is still debatable. In the present study, we evaluate the physical mechanism that may be primarily responsible for causing the sudden change in relativistic electron pitch angle distributions during a dropout event observed by Van Allen Probes during the main phase of the 27 February 2014 storm. During this event, t. . .
Date: 09/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022517 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022517/abstract
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Authors: Kanekal S G, Baker D N, Fennell J. F., Jones A., Schiller Q., et al.
Title: Prompt acceleration of magnetospheric electrons to ultrarelativistic energies by the 17 March 2015 interplanetary shock
Abstract: Trapped electrons in Earth's outer Van Allen radiation belt are influenced profoundly by solar phenomena such as high-speed solar wind streams, coronal mass ejections (CME), and interplanetary (IP) shocks. In particular, strong IP shocks compress the magnetosphere suddenly and result in rapid energization of electrons within minutes. It is believed that the electric fields induced by the rapid change in the geomagnetic field are responsible for the energization. During the latter part of March 2015, a CME impact led to the most powerful geomagnetic storm (minimum Dst = −223 nT at 17 March, 23 UT) observed not only during the Van Allen Probe era but also the entire preceding decade. Magnetospheric response in the outer radiation belt eventually resulted in elevated levels of energized ele. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 7622 - 7635 DOI: 10.1002/2016JA022596 Available at: http://doi.wiley.com/10.1002/2016JA022596
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Authors: Schiller Q., Kanekal S G, Jian L. K., Li X, Jones A., et al.
Title: Prompt injections of highly relativistic electrons induced by interplanetary shocks: A statistical study of Van Allen Probes observations
Abstract: We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated wi. . .
Date: 12/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071628 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071628/full
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Authors: Takahashi Kazue, Hartinger Michael D., Malaspina David M., Smith Charles W., Koga Kiyokazu, et al.
Title: Propagation of ULF waves from the upstream region to the midnight sector of the inner magnetosphere
Abstract: Ultralow frequency (ULF) waves generated in the ion foreshock are a well-known source of Pc3-Pc4 waves (7–100 mHz) observed in the dayside magnetosphere. We use data acquired on 10 April 2013 by multiple spacecraft to demonstrate that ULF waves of upstream origin can propagate to the midnight sector of the inner magnetosphere. At 1130–1730 UT on the selected day, the two Van Allen Probes spacecraft and the geostationary ETS-VIII satellite detected compressional 20 to 40 mHz magnetic field oscillations between L ∼ 4 and L ∼ 7 in the midnight sector, along with other spacecraft located closer to noon. Upstream origin of the oscillations is concluded from the wave frequency that matches a theoretical model, globally coherent amplitude modulation, and duskward propagation that is consi. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022958 Available at: http://doi.wiley.com/10.1002/2016JA022958
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Authors: Nomura R., Shiokawa K., Omura Y., Ebihara Y., Miyoshi Y, et al.
Title: Pulsating proton aurora caused by rising tone Pc1 waves
Abstract: We found rising tone emissions with a dispersion of ∼1 Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over ∼30 min from 0250 UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7°N, 246.7°E, magnetic latitude 61.7°N). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsations of an isolated proton aurora with a period of several tens of seconds, ∼10% variations in intensity, and fine structures of 3° in magnetic longitudes. The pulsations of the proton aurora close to the zenith of ATH have one-to-one correspondences with the Pc1 rising tones. This suggests. . .
Date: 02/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021681 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA021681/full
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Authors: Li W, Ma Q, Thorne R M, Bortnik J, Zhang X.-J., et al.
Title: Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations
Abstract: Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electron evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak loca. . .
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 5520 - 5536 DOI: 10.1002/jgra.v121.610.1002/2016JA022400 Available at: http://doi.wiley.com/10.1002/2016JA022400
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Authors: Jordanova V K, Tu W., Chen Y., Morley S. K., Panaitescu A.-D., et al.
Title: RAM-SCB simulations of electron transport and plasma wave scattering during the October 2012 “double-dip” storm
Abstract: Mechanisms for electron injection, trapping, and loss in the near-Earth space environment are investigated during the October 2012 “double-dip” storm using our ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB). Pitch angle and energy scattering are included for the first time in RAM-SCB using L and magnetic local time (MLT)-dependent event-specific chorus wave models inferred from NOAA Polar-orbiting Operational Environmental Satellites (POES) and Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science observations. The dynamics of the source (approximately tens of keV) and seed (approximately hundreds of keV) populations of the radiation belts simulated with RAM-SCB is compared with Van Allen Probes Magnetic Electron . . .
Date: 09/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022470 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022470/abstract
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Authors: Yue Chao, Li Wen, Nishimura Yukitoshi, Zong Qiugang, Ma Qianli, et al.
Title: Rapid enhancement of low-energy (<100 eV) ion flux in response to interplanetary shocks based on two Van Allen Probes case studies: Implications for source regions and heating mechanisms
Abstract: Interactions between interplanetary (IP) shocks and the Earth's magnetosphere manifest many important space physics phenomena including low-energy ion flux enhancements and particle acceleration. In order to investigate the mechanisms driving shock-induced enhancement of low-energy ion flux, we have examined two IP shock events that occurred when the Van Allen Probes were located near the equator while ionospheric and ground observations were available around the spacecraft footprints. We have found that, associated with the shock arrival, electromagnetic fields intensified, and low-energy ion fluxes, including H+, He+, and O+, were enhanced dramatically in both the parallel and perpendicular directions. During the 2 October 2013 shock event, both parallel and perpendicular flux enhancemen. . .
Date: 06/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022808 Available at: http://doi.wiley.com/10.1002/2016JA022808
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Authors: Soto-Chavez A. R., Lanzerotti L J, Gerrard A., Kim H., Bortnik J, et al.
Title: RBSPICE measurement of ion loss during the 2015 March storm: Adiabatic response to the geomagnetic field change
Abstract: A strongly energy-dependent ring current ion loss was measured by the RBSPICE instrument on the Van Allen Probes A spacecraft in the local evening sector during the 17 March 2015 geomagnetic storm. The ion loss is found to be energy dependent where only ions with energies measured above ∼ 150 keV have a significant drop in intensity. At these energies the ion dynamics are principally controlled by variations of the geomagnetic field which, during magnetic storms, exhibits large scale variations on timescales from minutes to hours. Here we show that starting from ∼ 19:10 UTC on March 17 the geomagnetic field increased from 220 to 260 nT on a time scale of about an hour as captured by RBSPICE-A close to spacecraft apogee, L = 6.1 and MLT = 21.85 hr. [GSM coordinates X=-4.89, Y=3.00, . . .
Date: 09/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022512 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA022512/abstract
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Authors: Andreeva Varvara A., and Tsyganenko Nikolai A.
Title: Reconstructing the magnetosphere from data using radial basis functions
Abstract: A new method is proposed to derive from data magnetospheric magnetic field configurations without any a priori assumptions on the geometry of electric currents. The approach utilizes large sets of archived satellite data and uses an advanced technique to represent the field as a sum of toroidal and poloidal parts, whose generating potentials Ψ1 and Ψ2 are expanded into series of radial basis functions (RBF) with their nodes regularly distributed over the 3D modeling domain. The method was tested by reconstructing the inner and high-latitude field within geocentric distances up to 12RE on the basis of magnetometer data of Geotail, Polar, Cluster, THEMIS, and Van Allen space probes, taken during 1995–2015. Four characteristic states of the magnetosphere before and during a disturbance ha. . .
Date: 02/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA022242 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA022242/full
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Authors: Yue Chao, An Xin, Bortnik Jacob, Ma Qianli, Li Wen, et al.
Title: The relationship between the macroscopic state of electrons and the properties of chorus waves observed by the Van Allen Probes
Abstract: Plasma kinetic theory predicts that a sufficiently anisotropic electron distribution will excite whistler mode waves, which in turn relax the electron distribution in such a way as to create an upper bound on the relaxed electron anisotropy. Here using whistler mode chorus wave and plasma measurements by Van Allen Probes, we confirm that the electron distributions are well constrained by this instability to a marginally stable state in the whistler mode chorus waves generation region. Lower band chorus waves are organized by the electron β∥e into two distinct groups: (i) relatively large-amplitude, quasi-parallel waves with inline image and (ii) relatively small-amplitude, oblique waves with inline image. The upper band chorus waves also have enhanced amplitudes close to the instabili. . .
Date: 08/2016 Publisher: Geophysical Research Letters Pages: 7804 - 7812 DOI: 10.1002/2016GL070084 Available at: http://doi.wiley.com/10.1002/2016GL070084
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Authors: Goldstein J, Baker D N, Blake J B, De Pascuale S., Funsten H O, et al.
Title: The relationship between the plasmapause and outer belt electrons
Abstract: We quantify the spatial relationship between the plasmapause and outer belt electrons for a 5 day period, 15–20 January 2013, by comparing locations of relativistic electron flux peaks to the plasmapause. A peak-finding algorithm is applied to 1.8–7.7 MeV relativistic electron flux data. A plasmapause gradient finder is applied to wave-derived electron number densities >10 cm−3. We identify two outer belts. Outer belt 1 is a stable zone of >3 MeV electrons located 1–2 RE inside the plasmapause. Outer belt 2 is a dynamic zone of <3 MeV electrons within 0.5 RE of the moving plasmapause. Electron fluxes earthward of each belt's peak are anticorrelated with cold plasma density. Belt 1 decayed on hiss timescales prior to a disturbance on 17 January and suffered only a modest dropout, pe. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023046 Available at: http://doi.wiley.com/10.1002/2016JA023046
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Authors: Kurita Satoshi, Miyoshi Yoshizumi, Blake Bernard, Reeves Geoffery D., and Kletzing Craig A.
Title: Relativistic electron microbursts and variations in trapped MeV electron fluxes during the 8-9 October 2012 storm: SAMPEX and Van Allen Probes observations
Abstract: It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Relativistic electron microbursts have been considered as an important loss mechanism of radiation belt electrons. Here we report on the observations of relativistic electron microbursts and flux variations of trapped MeV electrons during the 8–9 October 2012 storm, using the SAMPEX and Van Allen Probes satellites. Observations by the satellites show that relativistic electron microbursts correlate well with the rapid enhancement of trapped MeV electron fluxes by chorus wave-particle interactions, indicating that acceleration by chorus is much more efficient than losses by microbursts during the storm. It . . .
Date: 02/2016 Publisher: Geophysical Research Letters Pages: n/a - n/a DOI: 10.1002/2016GL068260 Available at: http://doi.wiley.com/10.1002/2016GL068260http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2016GL068260
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Authors: Ripoll J. F., Reeves G., Cunningham G., Loridan V., Denton M., et al.
Title: Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model
Abstract: We present dynamic simulations of energy-dependent losses in the radiation belt " slot region" and the formation of the two-belt structure for the quiet days after the March 1st storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally-resolved whistler mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L-shells (2 to 6) including (a) the strong energy-dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L-shells at lower energies and (c) an " S-shaped" energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial tran. . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL068869 Available at: http://doi.wiley.com/10.1002/2016GL068869
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Authors: Zhao H., Li X, Baker D N, Claudepierre S G, Fennell J. F., et al.
Title: Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements
Abstract: Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lower energy protons and higher-energy electrons are also found. The evolution of ring current electron and ion energy densi. . .
Date: 04/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 3333 - 3346 DOI: 10.1002/2016JA022358 Available at: http://doi.wiley.com/10.1002/2016JA022358
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Authors: Godinez Humberto C, Yu Yiqun, Lawrence Eric, Henderson Michael G., Larsen Brian A, et al.
Title: Ring Current Pressure Estimation with RAM-SCB using Data Assimilation and Van Allen Probe Flux Data
Abstract: Capturing and subsequently modeling the influence of tail plasma injections on the inner magnetosphere is important for understanding the formation and evolution of the ring current. In this study, the ring current distribution is estimated with the Ring Current-Atmosphere Interactions Model with Self-Consistent Magnetic field (RAM-SCB) using, for the first time, data assimilation techniques and particle flux data from the Van Allen Probes. The state of the ring current within the RAM-SCB model is corrected via an ensemble based data assimilation technique by using proton flux from one of the Van Allen Probes, to capture the enhancement of the ring current following an isolated substorm event on July 18, 2013. The results show significant improvement in the estimation of the ring current p. . .
Date: 11/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071646 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071646/full
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