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2019
Authors: Chen Huayue, Gao Xinliang, Lu Quanming, and Wang Shui
Title: Analyzing EMIC Waves in the Inner Magnetosphere Using Long‐Term Van Allen Probes Observations
Abstract: With 64‐month magnetic data from Van Allen Probes, we have studied not only the global distribution, wave normal angle (θ), and ellipticity (ε) of electromagnetic ion cyclotron (EMIC) waves, but also the dependence of their occurrence rates and magnetic amplitudes on the AE* index (the mean value of AE index over previous 1 hr). Our results show that H+ band waves are preferentially detected at 5 ≤ L ≤ 6.5, in the noon sector. They typically have small θ (<30°) and weakly left‐hand polarization but become more oblique and linearly polarized at larger magnetic latitudes or L‐shells. With the increase of AE* index, their occurrence rate significantly increases in the noon sector, and their source region extends to dusk sector. He+ band waves usually occur in the predawn and mor. . .
Date: 08/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 7402 - 7412 DOI: 10.1029/2019JA026965 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026965
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Authors: Baker D.N., Zhao H., Li X, Kanekal S.G., Jaynes A.N., et al.
Title: Comparison of Van Allen Probes Energetic Electron Data with Corresponding GOES‐15 Measurements: 2012‐2018
Abstract: Electron fluxes (especially at energies E > 0.8 and >2 MeV) have been measured for many years by sensors on board the Geostationary Operational Environmental Satellite (GOES). These long‐term data (nominally at L~6.6) have become a mainstay for monitoring the Earth's radiation environment. We have carried out a study directly comparing the comprehensive radiation belt particle measurements from the NASA dual‐spacecraft Van Allen Probes (Radiation Belt Storm Probes) sensor systems with selected GOES operational data. The Van Allen Probes have measured the properties of radiation belt electrons virtually continuously from September 2012 through 2018. We make statistical comparisons of Van Allen Probes electron data near L=6 with concurrent daily averages of equivalent GOES‐15 flux . . .
Date: 11/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027331 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027331
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Authors: Mager Olga V., Chelpanov Maksim A., Mager Pavel N., Klimushkin Dmitri Yu., and Berngardt Oleg I.
Title: Conjugate Ionosphere‐Magnetosphere Observations of a Sub‐Alfvénic Compressional Intermediate‐ m Wave: A Case Study Using EKB Radar and Van Allen Probes
Abstract: A Pc5 wave was simultaneously observed in the ionosphere by EKB radar and in the magnetosphere by both Van Allen Probe spacecraft within a substorm activity. The wave was located in the nightside, in 1.5‐ to 3‐hr magnetic local time sector, and in the region corresponding to the magnetic shells with maximal distances 4.6–7.8 Earth's radii. As it was found using both the radar and spacecraft data, the wave had frequency of about 1.8 mHz and azimuthal wave number m≈−10; that is, the wave was westward propagating. The EKB radar data revealed the equatorward wave propagating in the ionosphere, which corresponded to the earthward propagation in the magnetosphere. Furthermore, the field‐aligned magnetic component was approximately 2 times larger than both transverse components and ac. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026541 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026541
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Authors: Chen Margaret W., Lemon Colby L., Hecht James, Sazykin Stanislav, Wolf Richard A., et al.
Title: Diffuse Auroral Electron and Ion Precipitation Effects on RCM‐E Comparisons with Satellite Data During the March 17, 2013 Storm
Abstract: Effects of scattering of electrons from whistler chorus waves and of ions due to field line curvature on diffuse precipitating particle fluxes and ionospheric conductance during the large 17 March 2013 storm are examined using the self‐consistent Rice Convection Model Equilibrium (RCM‐E) model. Electrons are found to dominate the diffuse precipitating particle integrated energy flux, with large fluxes from ~21:00 magnetic local time (MLT) eastward to ~11:00 MLT during the storm main phase. Simulated proton and oxygen ion precipitation due to field line curvature scattering is sporadic and localized, occurring where model magnetic field lines are significantly stretched on the night side at equatorial geocentric radial distances r0 ≳8 RE and/or at r0 ~5.5 to 6.5 RE from dusk to midnig. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026545 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026545
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Authors: Yamamoto K., Nosé M., Keika K, Hartley D.P., Smith C.W., et al.
Title: Eastward Propagating Second Harmonic Poloidal Waves Triggered by Temporary Outward Gradient of Proton Phase Space Density: Van Allen Probe A Observation
Abstract: Two wave packets of second harmonic poloidal Pc 4 waves with a wave frequency of ~7 mHz were detected by Van Allen Probe A at a radial distance of ~5.8 RE and magnetic local time of 13 hr near the magnetic equator, where plasmaspheric refilling was in progress. Proton butterfly distributions with energy dispersions were also measured at the same time; the proton fluxes at 10‐30 keV oscillated with the same frequency as the Pc 4 waves. Using the ion sounding technique, we find that the Pc 4 waves propagated eastward with an azimuthal wave number (m number) of ~220 and ~260 for each wave packet, respectively. Such eastward propagating high‐m (m > 100) waves were seldom reported in previous studies. The condition of drift‐bounce resonance is well satisfied for the estimated m numbers in. . .
Date: 11/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027158 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027158
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Authors: Zhao H., Baker D N, Li X, Jaynes A. N., and Kanekal S G
Title: The Effects of Geomagnetic Storms and Solar Wind Conditions on the Ultrarelativistic Electron Flux Enhancements
Abstract: Using data from the Relativistic Electron Proton Telescope on the Van Allen Probes, the effects of geomagnetic storms and solar wind conditions on the ultrarelativistic electron (E > ~3 MeV) flux enhancements in the outer radiation belt, especially regarding their energy dependence, are investigated. It is showed that, statistically, more intense geomagnetic storms are indeed more likely to cause flux enhancements of ~1.8‐ to 7.7‐MeV electrons, though large variations exist. As the electron energy gets higher, the probability of flux enhancement gets lower. To shed light on which conditions of the storms are preferred to cause ultrarelativistic electron flux enhancement, detailed superposed epoch analyses of solar wind parameters and geomagnetic indices during moderate and intense stor. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 1948 - 1965 DOI: 10.1029/2018JA026257 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026257
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Authors: Smirnov A. G., Kronberg E. A., Latallerie F., Daly P. W., Aseev N. A., et al.
Title: Electron intensity measurements by the Cluster/RAPID/IES instrument in Earth's radiation belts and ring current
Abstract: The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earth's magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high‐energy electrons (<400 keV) and inner‐zone protons (230‐630 keV) in the radiation belts and ring current, the data have been rarely used for inner‐magnetospheric science. The current paper presents two algorithms for background correction. The first algorithm is based on the empirical contamination percentages by both protons and electrons. The second algorithm uses simultaneous proton observations. The efficiencies of these algorithms are demonstrated by comparison of the . . .
Date: 02/2019 Publisher: Space Weather DOI: 10.1029/2018SW001989 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW001989
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Authors: Smirnov A. G., Kronberg E. A., Latallerie F., Daly P. W., Aseev N. A., et al.
Title: Electron intensity measurements by the Cluster/RAPID/IES instrument in Earth's radiation belts and ring current
Abstract: The Cluster mission, launched in 2000, has produced a large database of electron flux intensity measurements in the Earth's magnetosphere by the Research with Adaptive Particle Imaging Detector (RAPID)/ Imaging Electron Spectrometer (IES) instrument. However, due to background contamination of the data with high‐energy electrons (<400 keV) and inner‐zone protons (230‐630 keV) in the radiation belts and ring current, the data have been rarely used for inner‐magnetospheric science. The current paper presents two algorithms for background correction. The first algorithm is based on the empirical contamination percentages by both protons and electrons. The second algorithm uses simultaneous proton observations. The efficiencies of these algorithms are demonstrated by comparison of the . . .
Date: 02/2019 Publisher: Space Weather DOI: 10.1029/2018SW001989 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW001989
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Authors: Andreeva V. A., and Tsyganenko N A
Title: Empirical Modeling of the Geomagnetosphere for SIR and CME‐Driven Magnetic Storms
Abstract: During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow‐fast stream interaction regions (SIRs). Previous data‐based magnetic field models did not distinguish between these types of the solar wind driving. In the present work we retained the basic structure of the Tsyganenko and Andreeva (2015) model but fitted it to data samples corresponding to (1) SIR‐driven storms, (2) CME‐driven storms preceded with a shock ahead of the CME, and (3) CME‐driven storms without such shocks. The storm time dynamics of the model current systems has been represented using the parametrization method developed by Tsyganenko and Sitnov. . .
Date: 07/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 5641 - 5662 DOI: 10.1029/2018JA026008 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026008
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Authors: Andreeva V. A., and Tsyganenko N A
Title: Empirical Modeling of the Geomagnetosphere for SIR and CME‐Driven Magnetic Storms
Abstract: During geomagnetic disturbances, the solar wind arrives in the form of characteristic sequences lasting from tens of hours to days. The most important magnetic storm drivers are the coronal mass ejections (CMEs) and the slow‐fast stream interaction regions (SIRs). Previous data‐based magnetic field models did not distinguish between these types of the solar wind driving. In the present work we retained the basic structure of the Tsyganenko and Andreeva (2015) model but fitted it to data samples corresponding to (1) SIR‐driven storms, (2) CME‐driven storms preceded with a shock ahead of the CME, and (3) CME‐driven storms without such shocks. The storm time dynamics of the model current systems has been represented using the parametrization method developed by Tsyganenko and Sitnov. . .
Date: 07/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 5641 - 5662 DOI: 10.1029/2018JA026008 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026008
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Authors: Stephens G. K., Sitnov M I, Korth H., Tsyganenko N A, Ohtani S, et al.
Title: Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Abstract: Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results i. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025843 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025843
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Authors: Stephens G. K., Sitnov M I, Korth H., Tsyganenko N A, Ohtani S, et al.
Title: Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Abstract: Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results i. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025843 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025843
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Authors: Stephens G. K., Sitnov M I, Korth H., Tsyganenko N A, Ohtani S, et al.
Title: Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Abstract: Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results i. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025843 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025843
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Authors: Zhao Wanli, Liu Si, Zhang Sai, Zhou Qinghua, Yang Chang, et al.
Title: Global Occurrences of Auroral Kilometric Radiation Related to Suprathermal Electrons in Radiation Belts
Abstract: Auroral kilometric radiation (AKR) can potentially produce serious damage to space‐borne systems by accelerating trapped radiation belt electrons to relativistic energies. Here we examine the global occurrences of AKR emissions in radiation belts based on Van Allen Probes observations from 1 October 2012 to 31 December 2016. The statistical results (1,848 events in total) show that AKR covers a broad region of L= 3–6.5 and 00–24 magnetic local time (MLT), with a higher occurrence on the nightside (20–24 MLT and 00–04 MLT) within L= 5–6.5. All the AKR events are observed to be accompanied with suprathermal (∼1 keV) electron flux enhancements. During active geomagnetic periods, both AKR occurrences and electron injections tend to be more distinct, and AKR emission extends to th. . .
Date: 07/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083944 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083944
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Authors: Chu Xiangning, Malaspina David, Gallardo‐Lacourt Bea, Liang Jun, Andersson Laila, et al.
Title: Identifying STEVE's Magnetospheric Driver Using Conjugate Observations in the Magnetosphere and on the Ground
Abstract: The magnetospheric driver of strong thermal emission velocity enhancement (STEVE) is investigated using conjugate observations when Van Allen Probes' footprint directly crossed both STEVE and stable red aurora (SAR) arc. In the ionosphere, STEVE is associated with subauroral ion drift features, including electron temperature peak, density gradient, and westward ion flow. The SAR arc at lower latitudes corresponds to regions inside the plasmapause with isotropic plasma heating, which causes redline‐only SAR emission via heat conduction. STEVE corresponds to the sharp plasmapause boundary containing quasi‐static subauroral ion drift electric field and parallel‐accelerated electrons by kinetic Alfvén waves. These parallel electrons could precipitate and be accelerated via auroral accel. . .
Date: 11/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082789 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082789
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Authors: Chu Xiangning, Malaspina David, Gallardo‐Lacourt Bea, Liang Jun, Andersson Laila, et al.
Title: Identifying STEVE's Magnetospheric Driver Using Conjugate Observations in the Magnetosphere and on the Ground
Abstract: The magnetospheric driver of strong thermal emission velocity enhancement (STEVE) is investigated using conjugate observations when Van Allen Probes' footprint directly crossed both STEVE and stable red aurora (SAR) arc. In the ionosphere, STEVE is associated with subauroral ion drift features, including electron temperature peak, density gradient, and westward ion flow. The SAR arc at lower latitudes corresponds to regions inside the plasmapause with isotropic plasma heating, which causes redline‐only SAR emission via heat conduction. STEVE corresponds to the sharp plasmapause boundary containing quasi‐static subauroral ion drift electric field and parallel‐accelerated electrons by kinetic Alfvén waves. These parallel electrons could precipitate and be accelerated via auroral accel. . .
Date: 11/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082789 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082789
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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: 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: 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: 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: 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: Stepanova M., Antonova E.E., Moya P.S., Pinto V.A., and Valdivia J.A.
Title: Multisatellite Analysis of Plasma Pressure in the Inner Magnetosphere During the 1 June 2013 Geomagnetic Storm
Abstract: Using data from Defense Meteorological Satellite Program 16–18, National Oceanic and Atmospheric Administration 15–19, and METOP 1–2 satellites, we reconstructed for the first time a two‐dimensional statistical distribution of plasma pressure in the inner magnetosphere during the 1 June 2013 geomagnetic storm with time resolution of 6 hr. Simultaneously, we used the data from Van Allen Probes and Time History of Events and Macroscale Interactions missions to obtain the in situ plasma pressure in the equatorial plane. This allowed us to corroborate that the dipole mapping works reasonably well during the storm time and that variations of plasma pressure are consistent at low and high altitudes; namely, we observed a drastic increase in plasma pressure a few hours before the storm on. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025965 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025965
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Authors: Wang Zihan, Zou Shasha, Shepherd Simon G., Liang Jun, Gjerloev Jesper W., et al.
Title: Multi‐instrument Observations of Mesoscale Enhancement of Subauroral Polarization Stream Associated With an Injection
Abstract: Subauroral polarization streams (SAPS) prefer geomagnetically disturbed conditions and strongly correlate with geomagnetic indexes. However, the temporal evolution of SAPS and its relationship with dynamic and structured ring current and particle injection are still not well understood. In this study, we performed detailed analysis of temporal evolution of SAPS during a moderate storm on 18 May 2013 using conjugate observations of SAPS from the Van Allen Probes (VAP) and the Super Dual Auroral Radar Network (SuperDARN). The large‐scale SAPS (LS‐SAPS) formed during the main phase of this storm and decayed due to the northward turning of the interplanetary magnetic field. A mesoscale (approximately several hundreds of kilometers zonally) enhancement of SAPS was observed by SuperDARN at 0. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 1770 - 1784 DOI: 10.1029/2019JA026535 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026535
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Authors: Kilpua E. K. J., Turner D. L., Jaynes A. N., Hietala H., Koskinen H. E. J., et al.
Title: Outer Van Allen Radiation Belt Response to Interacting Interplanetary Coronal Mass Ejections
Abstract: We study the response of the outer Van Allen radiation belt during an intense magnetic storm on 15–22 February 2014. Four interplanetary coronal mass ejections (ICMEs) arrived at Earth, of which the three last ones were interacting. Using data from the Van Allen Probes, we report the first detailed investigation of electron fluxes from source (tens of kiloelectron volts) to core (megaelectron volts) energies and possible loss and acceleration mechanisms as a response to substructures (shock, sheath and ejecta, and regions of shock‐compressed ejecta) in multiple interacting ICMEs. After an initial enhancement induced by a shock compression of the magnetosphere, core fluxes strongly depleted and stayed low for 4 days. This sustained depletion can be related to a sequence of ICME substruc. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 1927 - 1947 DOI: 10.1029/2018JA026238 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026238
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Authors: Wang G., Zhang T. L., Gao Z. L., Wu M. Y., Wang G. Q., et al.
Title: Propagation of EMIC Waves Inside the Plasmasphere: A Two‐Event Study
Abstract: Electromagnetic ion cyclotron (EMIC) waves are important for the loss of high‐energy electrons in the radiation belt. Based on the measurements of Van Allen Probes, two events during the same storm period are presented to study the propagation of EMIC waves. In the first event, left‐handed polarized EMIC waves were observed near the plasmapause, while right‐handed waves were observed in the inner plasmasphere. The Poynting flux of the right‐hand waves was mainly directed inward and equatorward, and no positive growth rates were obtained in the region of these right‐hand waves, indicating the inward propagation of the waves from a higher L‐shell. In the second event, the wave vectors were quasi‐perpendicular to the background magnetic field inside the plasmaspheric plume but b. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027055 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027055
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Authors: Dai Guyue, Su Zhenpeng, Liu Nigang, Wang Bin, Zheng Huinan, et al.
Title: Quenching of Equatorial Magnetosonic Waves by Substorm Proton Injections
Abstract: Near equatorial (fast) magnetosonic waves, characterized by high magnetic compressibility, are whistler‐mode emissions destabilized by proton shell/ring distributions. In the past, substorm proton injections are widely known to intensify magnetosonic waves in the inner magnetosphere. Here we report the unexpected observations by the Van Allen Probes of the magnetosonic wave quenching associated with the substorm proton injections under both high‐ and low‐density conditions. The enhanced proton thermal pressure distorted the background magnetic field configuration and the cold plasma density distribution. The reduced phase velocities locally allowed the weak growth or even damping of magnetosonic waves. Meanwhile, the spatially irregularly varying refractive indices might suppress the. . .
Date: 05/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL082944 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082944
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Authors: Claudepierre S G, O'Brien T P, Looper M D, Blake J B, Fennell J. F., et al.
Title: A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region
Abstract: We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inn. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026349 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026349
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Authors: Claudepierre S G, O'Brien T P, Looper M D, Blake J B, Fennell J. F., et al.
Title: A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region
Abstract: We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inn. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026349 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026349
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Authors: Lejosne Solène, and Mozer F S
Title: Shorting Factor In‐Flight Calibration for the Van Allen Probes DC Electric Field Measurements in the Earth's Plasmasphere
Abstract: Satellite‐based direct electric field measurements deliver crucial information for space science studies. Yet they require meticulous design and calibration. In‐flight calibration of double‐probe instruments is usually presented in the most common case of tenuous plasmas, where the presence of an electrostatic structure surrounding the charged spacecraft alters the geophysical electric field measurements. To account for this effect and the uncertainty in the boom length, the measured electric field is multiplied by a parameter called the shorting factor (sf). In the plasmasphere, the Debye length is very small in comparison with spacecraft dimension, and there is no shorting of the electric field measurements (sf = 1). However, the electric field induced by spacecraft motion greatly . . .
Date: 04/2019 Publisher: Earth and Space Science Pages: 646 - 654 DOI: 10.1029/2018EA000550 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018EA000550
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Authors: Thaller S. A., Wygant J R, Cattell C. A., Breneman A. W., Tyler E., et al.
Title: Solar rotation period driven modulations of plasmaspheric density and convective electric field in the inner magnetosphere
Abstract: This paper presents the first analysis of Van Allen Probes measurements of the cold plasma density and electric field in the inner magnetosphere to show that intervals of strong modulation at the solar rotation period occur in the locations of the outer plasmasphere and plasmapause (~0.7 RE peak‐to‐peak), in the large‐scale electric field (~0.24 mV/m peak‐to‐peak), and in the cold plasma density (~250 cm‐3 – ~70 cm‐3 peak‐to‐peak). Solar rotation modulation of the inner magnetosphere is more apparent in the declining phase of the solar cycle than near solar maximum. The periodicities in these parameters are compared to solar EUV irradiance, solar wind dawn‐dusk electric field, and Kp. The variations in the plasmapause location at the solar rotation period anti‐corre. . .
Date: 02/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026365 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026365
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Authors: Shen Xiao‐Chen, Li Wen, Ma Qianli, Agapitov Oleksiy, and Nishimura Yukitoshi
Title: Statistical Analysis of Transverse Size of Lower Band Chorus Waves Using Simultaneous Multisatellite Observations
Abstract: Chorus waves are known to accelerate or scatter energetic electrons via quasi‐linear or nonlinear wave‐particle interactions in the Earth's magnetosphere. In this letter, by taking advantage of simultaneous observations of chorus waveforms from at least a pair of probes among Van Allen Probes and/or Time History of Events and Macroscale Interactions during Substorms (THEMIS) missions, we statistically calculate the transverse size of lower band chorus wave elements. The average size of lower band chorus wave element is found to be ~315±32 km over L shells of ~5–6. Furthermore, our results suggest that the scale size of lower band chorus tends to be (1) larger at higher L shells; (2) larger at higher magnetic latitudes, especially on the dayside; and (3) larger in the azimuthal direc. . .
Date: 05/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL083118 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083118
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Authors: Jun C.-W., Yue C., Bortnik J, Lyons L R, Nishimura Y., et al.
Title: A Statistical Study of EMIC Waves Associated With and Without Energetic Particle Injection From the Magnetotail
Abstract: To understand the relationship between generation of electromagnetic ion cyclotron (EMIC) waves and energetic particle injections, we performed a statistical study of EMIC waves associated with and without injections based on the Van Allen Probes (Radiation Belt Storm Probes) and Geostationary Operational Environmental Satellite (GOES; GOES‐13 and GOES‐15) observations. Using 47 months of observations, we identified wave events seen by the Van Allen Probes relative to the plasmapause and to energetic particle injections seen by GOES‐13 and GOES‐15 on the nightside. We separated the events into four categories: EMIC waves with (without) injections inside (outside) the plasmasphere. We found that He+ EMIC waves have higher occurrence rate inside the plasmasphere, while H+ EMIC waves . . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 433 - 450 DOI: 10.1029/2018JA025886 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025886
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Authors: Jun C.-W., Yue C., Bortnik J, Lyons L R, Nishimura Y., et al.
Title: A Statistical Study of EMIC Waves Associated With and Without Energetic Particle Injection From the Magnetotail
Abstract: To understand the relationship between generation of electromagnetic ion cyclotron (EMIC) waves and energetic particle injections, we performed a statistical study of EMIC waves associated with and without injections based on the Van Allen Probes (Radiation Belt Storm Probes) and Geostationary Operational Environmental Satellite (GOES; GOES‐13 and GOES‐15) observations. Using 47 months of observations, we identified wave events seen by the Van Allen Probes relative to the plasmapause and to energetic particle injections seen by GOES‐13 and GOES‐15 on the nightside. We separated the events into four categories: EMIC waves with (without) injections inside (outside) the plasmasphere. We found that He+ EMIC waves have higher occurrence rate inside the plasmasphere, while H+ EMIC waves . . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 433 - 450 DOI: 10.1029/2018JA025886 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025886
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Authors: Wang Hui, He Yangfan, ühr Hermann, Kistler Lynn, Saikin Anthony, et al.
Title: Storm Time EMIC Waves Observed by Swarm and Van Allen Probe Satellites
Abstract: The temporal and spatial evolution of electromagnetic ion cyclotron (EMIC) waves during the magnetic storm of 21–29 June 2015 was investigated using high‐resolution magnetic field observations from Swarm constellation in the ionosphere and Van Allen Probes in the magnetosphere. Magnetospheric EMIC waves had a maximum occurrence frequency in the afternoon sector and shifted equatorward during the expansion phase and poleward during the recovery phase. However, ionospheric waves in subauroral regions occurred more frequently in the nighttime than during the day and exhibited less obvious latitudinal movements. During the main phase, dayside EMIC waves occurred in both the ionosphere and magnetosphere in response to the dramatic increase in the solar wind dynamic pressure. Waves were abse. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 293 - 312 DOI: 10.1029/2018JA026299 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026299
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Authors: Wang Hui, He Yangfan, ühr Hermann, Kistler Lynn, Saikin Anthony, et al.
Title: Storm Time EMIC Waves Observed by Swarm and Van Allen Probe Satellites
Abstract: The temporal and spatial evolution of electromagnetic ion cyclotron (EMIC) waves during the magnetic storm of 21–29 June 2015 was investigated using high‐resolution magnetic field observations from Swarm constellation in the ionosphere and Van Allen Probes in the magnetosphere. Magnetospheric EMIC waves had a maximum occurrence frequency in the afternoon sector and shifted equatorward during the expansion phase and poleward during the recovery phase. However, ionospheric waves in subauroral regions occurred more frequently in the nighttime than during the day and exhibited less obvious latitudinal movements. During the main phase, dayside EMIC waves occurred in both the ionosphere and magnetosphere in response to the dramatic increase in the solar wind dynamic pressure. Waves were abse. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 293 - 312 DOI: 10.1029/2018JA026299 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026299
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Authors: Wang Hui, He Yangfan, ühr Hermann, Kistler Lynn, Saikin Anthony, et al.
Title: Storm Time EMIC Waves Observed by Swarm and Van Allen Probe Satellites
Abstract: The temporal and spatial evolution of electromagnetic ion cyclotron (EMIC) waves during the magnetic storm of 21–29 June 2015 was investigated using high‐resolution magnetic field observations from Swarm constellation in the ionosphere and Van Allen Probes in the magnetosphere. Magnetospheric EMIC waves had a maximum occurrence frequency in the afternoon sector and shifted equatorward during the expansion phase and poleward during the recovery phase. However, ionospheric waves in subauroral regions occurred more frequently in the nighttime than during the day and exhibited less obvious latitudinal movements. During the main phase, dayside EMIC waves occurred in both the ionosphere and magnetosphere in response to the dramatic increase in the solar wind dynamic pressure. Waves were abse. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 293 - 312 DOI: 10.1029/2018JA026299 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026299
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Authors: Mouikis C. G., Bingham S. T., Kistler L. M., Farrugia C. J., Spence H E, et al.
Title: The Storm‐Time Ring Current Response to ICMEs and CIRs Using Van Allen Probe Observations
Abstract: Using Van Allen Probe observations of the inner magnetosphere during geomagnetic storms driven by interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs), we characterize the impact of these drivers on the storm‐time ring current development. Using 25 ICME‐ and 35 CIR‐driven storms, we have determined the ring current pressure development during the prestorm, main, early‐recovery, and late‐recovery storm phases, as a function of magnetic local time, L shell and ion species (H+, He+, and O+) over the 100‐ to 600‐keV energy range. Consistent with previous results, we find that during the storm main phase, most of the ring current pressure in the inner magnetosphere is contributed by particles on open drift paths drifting duskward leading to a str. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026695 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026695
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Authors: Sandhu J. K., Rae I. J., Freeman M. P., Gkioulidou M., Forsyth C., et al.
Title: Substorm‐Ring Current Coupling: A Comparison of Isolated and Compound Substorms
Abstract: Substorms are a highly variable process, which can occur as an isolated event or as part of a sequence of multiple substorms (compound substorms). In this study we identify how the low‐energy population of the ring current and subsequent energization varies for isolated substorms compared to the first substorm of a compound event. Using observations of H+ and O+ ions (1 eV to 50 keV) from the Helium Oxygen Proton Electron instrument onboard Van Allen Probe A, we determine the energy content of the ring current in L‐MLT space. We observe that the ring current energy content is significantly enhanced during compound substorms as compared to isolated substorms by ∼20–30%. Furthermore, we observe a significantly larger magnitude of energization (by ∼40–50%) following the onset of c. . .
Date: 08/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 6776 - 6791 DOI: 10.1029/2019JA026766 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026766
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Authors: Watt C. E. J., Allison H. J., Meredith N P, Thompson R. L., Bentley S. N., et al.
Title: Variability of Quasilinear Diffusion Coefficients for Plasmaspheric Hiss
Abstract: In the outer radiation belt, the acceleration and loss of high‐energy electrons is largely controlled by wave‐particle interactions. Quasilinear diffusion coefficients are an efficient way to capture the small‐scale physics of wave‐particle interactions due to magnetospheric wave modes such as plasmaspheric hiss. The strength of quasilinear diffusion coefficients as a function of energy and pitch angle depends on both wave parameters and plasma parameters such as ambient magnetic field strength, plasma number density, and composition. For plasmaspheric hiss in the magnetosphere, observations indicate large variations in the wave intensity and wave normal angle, but less is known about the simultaneous variability of the magnetic field and number density. We use in situ measurements. . .
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026401 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026401
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Authors: Pandya Megha, Veenadhari B., Ebihara Y., Kanekal S.G., and Baker D.N.
Title: Variation of Radiation belt electron flux during CME and CIR driven geomagnetic storms: Van Allen Probes observations
Abstract: Relativistic electron flux responses in the inner magnetosphere are investigated for 28 magnetic storms driven by Corotating Interaction Region (CIR) and 27 magnetic storms driven by Coronal Mass Ejection (CME), using data from the Relativistic Electron‐Proton Telescope (REPT) instrument on board Van‐Allen Probes from Oct‐2012 to May‐2017. In this present study we analyze the role of CIRs and CMEs in electron dynamics by sorting the electron fluxes in terms of averaged solar wind parameters, L‐values, and energies. The major outcomes from our study are: (i) At L = 3 and E = 3.4 MeV, for >70% cases the electron flux remains stable, while at L = 5, for ~82% cases it changes with the geomagnetic conditions. (ii) At L = 5, ~53% of the CIR storms and 30% of the CME storms show electro. . .
Date: 07/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026771 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026771
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Authors: Zou Zhengyang, Zuo Pingbing, Ni Binbin, Wei Fengsi, Zhao Zhengyu, et al.
Title: Wave Normal Angle Distribution of Fast Magnetosonic Waves: A Survey of Van Allen Probes EMFISIS Observations
Abstract: Using Van Allen Probe Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) wave observations from September 2012 to May 2018, we statistically investigate the distributions of power‐weighted wave normal angle (WNA) of fast magnetosonic (MS) waves from L = 2–6 within ±15° geomagnetic latitudes. The spatial distributions show that the MS WNAs are mainly confined within 87–89° near the geomagnetic equator and decrease with increasing magnetic latitude. Further quantitative investigation demonstrates that the WNAs normally distribute as a mixture of two Gaussian distributions ranging from 85° to 88°, and the tangent of it can decrease as a Kappa distribution function when the waves propagate to higher latitudes. Our study completes the survey of spatial dist. . .
Date: 07/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 5663 - 5674 DOI: 10.1029/2019JA026556 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026556
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2018
Authors: Fathy A., Kim K.-H., Park J.-S., Jin H., Kletzing C., et al.
Title: Characteristics of Sudden Commencements Observed by Van Allen Probes in the Inner Magnetosphere
Abstract: We have statistically studied sudden commencement (SC) by using the data acquired from Van Allen Probes (VAP) in the inner magnetosphere (L = 3.0–6.5) and GOES spacecraft at geosynchronous orbit (L =∼ 6.7) from October 2012 to September 2017. During the time period, we identified 85 SCs in the inner magnetosphere and 90 SCs at geosynchronous orbit. Statistical results of the SC events reveal the following characteristics. (1) There is strong seasonal dependence of the geosynchronous SC amplitude in the radial BV component at all local times. However, BV shows weak seasonal variation on the dayside in the inner magnetosphere. (2) The local time dependence of the SC amplitude in the compressional BH component at geosynchronous orbit is similar to that in the inner magnetosphere. (3) In a. . .
Date: 02/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024770 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024770/full
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Authors: Ren Jie, Zong Qiu-Gang, Miyoshi Yoshizumi, Rankin Robert, Spence Harlan E, et al.
Title: A comparative study of ULF waves' role in the dynamics of charged particles in the plasmasphere: Van Allen Probes observation
Abstract: By analyzing observations from Van Allen Probes in its inbound and outbound orbits, we present evidence of coherent enhancement of cold plasmaspheric electrons and ions due to drift‐bounce resonance with ULF waves. From 18:00 UT on 28 May 2017 to 10:00 UT on 29 May 2017, newly formed poloidal mode standing ULF waves with significant electric field oscillations were observed in two consecutive orbits when Probe B was travelling inbound. In contrast to observations during outbound orbits, the cold (< 150 eV) electorns measured by the HOPE instrument were characterized by flux enhancements several times larger and bi‐directional pitch angle distributions during inbound orbits. The electron number density inferred from upper hybrid waves is twice as larger as during inbound orbits, which w. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025255 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025255
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Authors: Allison Hayley J., Horne Richard B, Glauert Sarah A, and Del Zanna Giulio
Title: Determination of the Equatorial Electron Differential Flux From Observations at Low Earth Orbit
Abstract: Variations in the high‐energy relativistic electron flux of the radiation belts depend on transport, acceleration, and loss processes, and importantly on the lower‐energy seed population. However, data on the seed population is limited to a few satellite missions. Here we present a new method that utilizes data from the Medium Energy Proton/Electron Detector on board the low‐altitude Polar Operational Environmental Satellites to retrieve the seed population at a pitch angle of 90°. The integral flux values measured by Medium Energy Proton/Electron Detector relate to a low equatorial pitch angle and were converted to omnidirectional flux using parameters obtained from fitting one or two urn:x-wiley:jgra:media:jgra54628:jgra54628-math-0001 functions to pitch angle distributions given . . .
Date: 11/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025786 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025786
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Authors: Zhang X.-J., Mourenas D., Artemyev A. V., Angelopoulos V, and Thorne R M
Title: Electron flux enhancements at L  = 4.2 observed by Global Positioning System satellites: Relationship with solar wind and geomagnetic activity
Abstract: Determining solar wind and geomagnetic activity parameters most favorable to strong electron flux enhancements is an important step towards forecasting radiation belt dynamics. Using electron flux measurements from Global Positioning System satellites at L = 4.2 in 2009‐2016, we seek statistical relationships between flux enhancements at different energies and solar wind dynamic pressure Pdyn, AE, and Kp, from hundreds of events inside and outside the plasmasphere. Most ⩾1 MeV electron flux enhancements occur during non‐storm (or weak storm) times. Flux enhancements of 4 MeV electrons outside the plasmasphere occur during periods of low Pdyn and high AE. We perform superposed epoch analyses of GPS electron fluxes, along with solar wind and geomagnetic indices, 40 keV electron flu. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025497 Available at: http://doi.wiley.com/10.1029/2018JA025497http://onlinelibrary.wiley.com/wol1/doi/10.1029/2018JA025497/fullpdfhttps://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1029%2F2018JA025497
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Authors: Mourenas D., Zhang X.-J., Artemyev A. V., Angelopoulos V, Thorne R M, et al.
Title: Electron nonlinear resonant interaction with short and intense parallel chorus wave-packets
Abstract: One of the major drivers of radiation belt dynamics, electron resonant interaction with whistler‐mode chorus waves, is traditionally described using the quasi‐linear diffusion approximation. Such a description satisfactorily explains many observed phenomena, but its applicability can be justified only for sufficiently low intensity, long duration waves. Recent spacecraft observations of a large number of very intense lower band chorus waves (with magnetic field amplitudes sometimes reaching ∼1% of the background) therefore challenge this traditional description, and call for an alternative approach when addressing the global, long‐term effects of the nonlinear interaction of these waves with radiation belt electrons. In this paper, we first use observations from the Van Allen Probe. . .
Date: 05/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025417 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025417
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Authors: Lejosne ène, Kunduri B. S. R., Mozer F S, and Turner D. L.
Title: Energetic electron injections deep into the inner magnetosphere: a result of the subauroral polarization stream (SAPS) potential drop
Abstract: It has been reported that the dynamics of energetic (tens to hundreds of keV) electrons and ions is inconsistent with the theoretical picture in which the large‐scale electric field is a superposition of corotation and convection electric fields. Combining one year of measurements by the Super Dual Auroral Radar Network, DMSP F‐18 and the Van Allen Probes, we show that subauroral polarization streams are observed when energetic electrons have penetrated below L = 4. Outside the plasmasphere in the premidnight region, potential energy is subtracted from the total energy of ions and added to the total energy of electrons during SAPS onset. This potential energy is converted into radial motion as the energetic particles drift around Earth and leave the SAPS azimuthal sector. As a result, . . .
Date: 04/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL077969 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077969
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Authors: Sandhu J. K., Rae I. J., Freeman M. P., Forsyth C., Gkioulidou M., et al.
Title: Energisation of the ring current by substorms
Abstract: The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energisation processes provides valuable insight into how substorm ‐ ring current coupling may contribute to the generation of storm conditions and provide a source of energy for wave driving. In order to quantify the energy input into the ring current during the substorm process, we analyse RBSPICE and HOPE ion flux measurements for H+, O+, and He+. The energy content of the ring current is estimated and binned spatially for. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025766 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025766
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Authors: Murphy Kyle R., Watt C. E. J., Mann Ian R., Rae Jonathan, Sibeck David G., et al.
Title: The global statistical response of the outer radiation belt during geomagnetic storms
Abstract: Using the total radiation belt electron content calculated from Van Allen Probe phase space density (PSD), the time‐dependent and global response of the outer radiation belt during storms is statistically studied. Using PSD reduces the impacts of adiabatic changes in the main phase, allowing a separation of adiabatic and non‐adiabatic effects, and revealing a clear modality and repeatable sequence of events in storm‐time radiation belt electron dynamics. This sequence exhibits an important first adiabatic invariant (μ) dependent behaviour in the seed (150 MeV/G), relativistic (1000 MeV/G), and ultra‐relativistic (4000 MeV/G) populations. The outer radiation belt statistically shows an initial phase dominated by loss followed by a second phase of rapid acceleration, whilst the seed. . .
Date: 04/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076674 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017GL076674
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Authors: Murphy Kyle R., Watt C. E. J., Mann Ian R., Rae Jonathan, Sibeck David G., et al.
Title: The global statistical response of the outer radiation belt during geomagnetic storms
Abstract: Using the total radiation belt electron content calculated from Van Allen Probe phase space density (PSD), the time‐dependent and global response of the outer radiation belt during storms is statistically studied. Using PSD reduces the impacts of adiabatic changes in the main phase, allowing a separation of adiabatic and non‐adiabatic effects, and revealing a clear modality and repeatable sequence of events in storm‐time radiation belt electron dynamics. This sequence exhibits an important first adiabatic invariant (μ) dependent behaviour in the seed (150 MeV/G), relativistic (1000 MeV/G), and ultra‐relativistic (4000 MeV/G) populations. The outer radiation belt statistically shows an initial phase dominated by loss followed by a second phase of rapid acceleration, whilst the seed. . .
Date: 04/2018 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL076674 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017GL076674
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