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Journal Article
Authors: Sergeev V. A., Nikolaev A. V., Tsyganenko N A, Angelopoulos V, Runov A. V., et al.
Title: Testing a two-loop pattern of the substorm current wedge (SCW2L)
Abstract: Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model parameters. During two cases of a dipole-like magnetotail configuration, the dipolarization/injection front fortuitously stopped at r ~ 9RE for the entire duration of ~ 30 min long SCW-related dipolarization within a unique, radially distributed multispacecraft constellat. . .
Date: 02/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 947 - 963 DOI: 10.1002/2013JA019629 Available at: http://doi.wiley.com/10.1002/2013JA019629
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Authors: Califf S., Li X, Blum L., Jaynes A., Schiller Q., et al.
Title: THEMIS measurements of quasi-static electric fields in the inner magnetosphere
Abstract: We use four years of THEMIS double-probe measurements to offer, for the first time, a complete picture of the dawn-dusk electric field covering all local times and radial distances in the inner magnetosphere based on in situ equatorial observations. This study is motivated by the results from the CRRES mission, which revealed a local maximum in the electric field developing near Earth during storm times, rather than the expected enhancement at higher L shells that is shielded near Earth as suggested by the Volland-Stern model. The CRRES observations were limited to the dusk side, while THEMIS provides complete local time coverage. We show strong agreement with the CRRES results on the dusk side, with a local maximum near L =4 for moderate levels of geomagnetic activity and evidence of stro. . .
Date: 10/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020360 Available at: http://doi.wiley.com/10.1002/2014JA020360
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Authors: Macek W. M., Wawrzaszek A., and Sibeck D G
Title: THEMIS observation of intermittent turbulence behind the quasi-parallel and quasi-perpendicular shocks
Abstract: Turbulence is complex behavior that is ubiquitous in nature, but its mechanism is still not sufficiently clear. Therefore, the main aim of this paper is analysis of intermittent turbulence in magnetospheric and solar wind plasmas using a statistical approach based on experimental data acquired from space missions. The quintet spacecraft of Time History of Events and Macroscale Interactions during Substorms (THEMIS) allows us to investigate the details of turbulent plasma parameters behind the collisionless shocks. We investigate both the solar wind and magnetospheric data by using statistical probability distribution functions of Elsässer variables that can reveal the intermittent character of turbulence in space plasma. Our results suggest that turbulence behind the quasi-perpendicular s. . .
Date: 09/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 7466 - 7476 DOI: 10.1002/2015JA021656 Available at: http://doi.wiley.com/10.1002/2015JA021656http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021656
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Authors: Zhang J.-C., Kistler L. M., Spence H E, Wolf R. A., Reeves G., et al.
Title: “Trunk-like” heavy ion structures observed by the Van Allen Probes
Abstract: Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. We report “trunk-like” ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant's trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He+ and O+ ions but not in H+. During the event, ion energies in the He+ trunk, located at L = 3.6–2.6, MLT = 9.1–10.5, and MLAT = −2.4–0.09°, vary monotonically from 3.5 to 0.04 keV. The values at the two end points of the O+ trunk are: energy = 4.5–0.7 keV, L = 3.6–2.5, MLT = 9.1–10.7, and MLAT = −2.4–0.4°. Results from backward ion drift path tra. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021822 Available at: http://doi.wiley.com/10.1002/2015JA021822http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021822
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Authors: Zhang J.-C., Kistler L. M., Spence H E, Wolf R. A., Reeves G., et al.
Title: “Trunk-like” heavy ion structures observed by the Van Allen Probes
Abstract: Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. We report “trunk-like” ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant's trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He+ and O+ ions but not in H+. During the event, ion energies in the He+ trunk, located at L = 3.6–2.6, MLT = 9.1–10.5, and MLAT = −2.4–0.09°, vary monotonically from 3.5 to 0.04 keV. The values at the two end points of the O+ trunk are: energy = 4.5–0.7 keV, L = 3.6–2.5, MLT = 9.1–10.7, and MLAT = −2.4–0.4°. Results from backward ion drift path tra. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021822 Available at: http://doi.wiley.com/10.1002/2015JA021822http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021822
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Authors: Zhang J.-C., Kistler L. M., Spence H E, Wolf R. A., Reeves G., et al.
Title: “Trunk-like” heavy ion structures observed by the Van Allen Probes
Abstract: Dynamic ion spectral features in the inner magnetosphere are the observational signatures of ion acceleration, transport, and loss in the global magnetosphere. We report “trunk-like” ion structures observed by the Van Allen Probes on 2 November 2012. This new type of ion structure looks like an elephant's trunk on an energy-time spectrogram, with the energy of the peak flux decreasing Earthward. The trunks are present in He+ and O+ ions but not in H+. During the event, ion energies in the He+ trunk, located at L = 3.6–2.6, MLT = 9.1–10.5, and MLAT = −2.4–0.09°, vary monotonically from 3.5 to 0.04 keV. The values at the two end points of the O+ trunk are: energy = 4.5–0.7 keV, L = 3.6–2.5, MLT = 9.1–10.7, and MLAT = −2.4–0.4°. Results from backward ion drift path tra. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021822 Available at: http://doi.wiley.com/10.1002/2015JA021822http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021822
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Authors: Lejosne ène, and Mozer F S
Title: Typical values of the electric drift E  ×  B / B 2 in the inner radiation belt and slot region as determined from Van Allen Probe measurements
Abstract: The electric drift E × B/B2 plays a fundamental role for the description of plasma flow and particle acceleration. Yet it is not well-known in the inner belt and slot region because of a lack of reliable in situ measurements. In this article, we present an analysis of the electric drifts measured below L ~ 3 by both Van Allen Probes A and B from September 2012 to December 2014. The objective is to determine the typical components of the equatorial electric drift in both radial and azimuthal directions. The dependences of the components on radial distance, magnetic local time, and geographic longitude are examined. The results from Van Allen Probe A agree with Van Allen Probe B. They show, among other things, a typical corotation lag of the order of 5 to 10% below L ~ 2.6, as w. . .
Date: 12/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023613 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023613/full
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Authors: Millan R.M.
Title: Understanding relativistic electron losses with BARREL
Abstract: The primary scientific objective of the Balloon Array for RBSP Relativistic Electron Losses (BARREL) is to understand the processes responsible for scattering relativistic electrons into Earth's atmosphere. BARREL is the first Living with a Star Geospace Mission of Opportunity, and will consist of two Antarctic balloon campaigns conducted in the 2012 and 2013 Austral summer seasons. During each campaign, a total of 20 small View the MathML source(∼20kg) balloon payloads will be launched, providing multi-point measurements of electron precipitation in conjunction with in situ measurements from the two RBSP spacecraft, scheduled to launch in May 2012. In this paper we outline the scientific objectives of BARREL, highlighting a few key science questions that will be addressed by BARREL in c. . .
Date: 07/2011 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 1425 - 1434 DOI: 10.1016/j.jastp.2011.01.006 Available at: http://www.sciencedirect.com/science/article/pii/S1364682611000071
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Authors: Yang Xiao C., Zhu Guang W., Zhang Xiao X., Sun Yue Q., Liang Jin B., et al.
Title: An unusual long-lived relativistic electron enhancement event excited by sequential CMEs
Abstract: An unusual long-lived intense relativistic electron enhancement event from July to August 2004 is examined using data from Fengyun-1, POES, GOES, ACE, the Cluster Mission and geomagnetic indices. During the initial 6 days of this event, the observed fluxes in the outer zone enhanced continuously and their maximum increased from 2.1 × 102 cm-2·sr-1·s-1 to 3.5 × 104 cm-2·sr-1·s-1, the region of enhanced fluxes extended from L = 3.5-6.5 to L = 2.5-6.5, and the flux peak location shifted inward from L ~ 4.2 to L ~ 3.3. During the following 7 days, without any locational movement, the flux peak increased slowly and exceeded the pre-storm fluxes by about 4 orders of magnitude. Subsequently, the decay rate of relativistic electrons is so slow that the peak re. . .
Date: 10/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA019797 Available at: http://doi.wiley.com/10.1002/2014JA019797
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Authors: Lejosne Solène, and Mozer F S
Title: Van Allen Probe measurements of the electric drift E × B/B2 at Arecibo's L = 1.4 field line coordinate
Abstract: We have used electric and magnetic measurements by Van Allen Probe B from 2013 to 2014 to examine the equatorial electric drift E × B/B2 at one field line coordinate set to Arecibo's incoherent scatter radar location (L = 1.43). We report on departures from the traditional picture of corotational motion with the Earth in two ways: (1) the rotational angular speed is found to be 10% smaller than the rotational angular speed of the Earth, in agreement with previous works on plasmaspheric notches, and (2) the equatorial electric drift displays a dependence in magnetic local time, with a pattern consistent with the mapping of the Arecibo ionosphere dynamo electric fields along equipotential magnetic field lines. The electric fields due to the ionosphere dynamo are therefore expected t. . .
Date: 07/2016 Publisher: Geophysical Research Letters Pages: 6768 - 6774 DOI: 10.1002/2016GL069875 Available at: http://doi.wiley.com/10.1002/2016GL069875
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Authors: Lejosne Solène, and Mozer F S
Title: Van Allen Probe measurements of the electric drift E × B/B2 at Arecibo's L = 1.4 field line coordinate
Abstract: We have used electric and magnetic measurements by Van Allen Probe B from 2013 to 2014 to examine the equatorial electric drift E × B/B2 at one field line coordinate set to Arecibo's incoherent scatter radar location (L = 1.43). We report on departures from the traditional picture of corotational motion with the Earth in two ways: (1) the rotational angular speed is found to be 10% smaller than the rotational angular speed of the Earth, in agreement with previous works on plasmaspheric notches, and (2) the equatorial electric drift displays a dependence in magnetic local time, with a pattern consistent with the mapping of the Arecibo ionosphere dynamo electric fields along equipotential magnetic field lines. The electric fields due to the ionosphere dynamo are therefore expected t. . .
Date: 07/2016 Publisher: Geophysical Research Letters Pages: 6768 - 6774 DOI: 10.1002/2016GL069875 Available at: http://doi.wiley.com/10.1002/2016GL069875
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Authors: Korotova G. I., Sibeck D G, Tahakashi K., Dai L., Spence H E, et al.
Title: Van Allen Probe observations of drift-bounce resonances with Pc 4 pulsations and wave–particle interactions in the pre-midnight inner magnetosphere
Abstract: We present Van Allen Probe B observations of azimuthally limited, antisymmetric, poloidal Pc 4 electric and magnetic field pulsations in the pre-midnight sector of the magnetosphere from 05:40 to 06:00 UT on 1 May 2013. Oscillation periods were similar for the magnetic and electric fields and proton fluxes. The flux of energetic protons exhibited an energy-dependent response to the pulsations. Energetic proton variations were anticorrelated at medium and low energies. Although we attribute the pulsations to a drift-bounce resonance, we demonstrate that the energy-dependent response of the ion fluxes results from pulsation-associated velocities sweeping energy-dependent radial ion flux gradients back and forth past the spacecraft.
Date: 01/2015 Publisher: Annales Geophysicae Pages: 955 - 964 DOI: 10.5194/angeo-33-955-2015 Available at: http://www.ann-geophys.net/33/955/2015/angeo-33-955-2015.pdf
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Authors: Boardsen S. A., Hospodarsky G B, Kletzing C A, Pfaff R. F., Kurth W S, et al.
Title: Van Allen Probe Observations of Periodic Rising Frequencies of the Fast Magnetosonic Mode
Abstract: Near simultaneous periodic dispersive features of fast magnetosonic mode emissions are observed by both Van Allen Probes spacecraft while separated in magnetic local time by ~5 hours: Probe A at 15 and Probe B at 9–11 hours. Both spacecraft see similar frequency features, characterized by a periodic repetition at ~180 s. Each repetition is characterized by a rising frequency. Since no modulation is observed in the proton shell distribution, the plasma density, or in the background magnetic field at either spacecraft we conclude that these waves are not generated near the spacecraft but external to both spacecraft locations. Probe A while outside the plasmapause sees the start of each repetition ~40 s before probe B while deep inside the plasmasphere. We can qualitatively reproduce . . .
Date: 12/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062020 Available at: http://doi.wiley.com/10.1002/2014GL062020
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Authors: Thaller S. A., Wygant J R, Dai L., Breneman A.W., Kersten K., et al.
Title: Van Allen Probes investigation of the large scale duskward electric field and its role in ring current formation and plasmasphere erosion in the June 1, 2013 storm
Abstract: Using the Van Allen Probes we investigate the enhancement in the large scale duskward convection electric field during the geomagnetic storm (Dst ~ −120 nT) on June 1, 2013 and its role in ring current ion transport and energization, and plasmasphere erosion. During this storm, enhancements of ~1-2 mV/m in the duskward electric field in the co-rotating frame are observed down to L shells as low as ~2.3. A simple model consisting of a dipole magnetic field and constant, azimuthally westward, electric field is used to calculate the earthward and westward drift of 90° pitch angle ions. This model is applied to determine how far earthward ions can drift while remaining on Earth's night side, given the strength and duration of the convection electric field. The calculation based on this simp. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020875 Available at: http://doi.wiley.com/10.1002/2014JA020875
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Authors: Chen X.-R., Zong Q.-G., Zhou X.-Z., Blake Bernard, Wygant John R., et al.
Title: Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves
Abstract: We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultra-low frequency (ULF) waves on October 29, 2013. Oscillations in electron flux were observed at the period of ∼450s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (∼50 to 150 keV) across the estimated resonant energy (∼104 keV) is ∼360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic . . .
Date: 12/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071252 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071252/full
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Authors: Chen X.-R., Zong Q.-G., Zhou X.-Z., Blake Bernard, Wygant J. R., et al.
Title: Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves
Abstract: We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ∼450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (∼50 to 150 keV) across the estimated resonant energy (∼104 keV) is ∼360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic p. . .
Date: 02/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL071252 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071252/full
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Authors: é M., Keika K, Kletzing C A, Spence H E, Smith C W, et al.
Title: Van Allen Probes observations of magnetic field dipolarization and its associated O + flux variations in the inner magnetosphere at L  < 6.6
Abstract: We investigate magnetic field dipolarization in the inner magnetosphere and its associated ion flux variations, using the magnetic field and energetic ion flux data acquired by the Van Allen Probes. From a study of 74 events that appeared at L = 4.5–6.6 between 1 October 2012 and 31 October 2013, we reveal the following characteristics of the dipolarization in the inner magnetosphere: (1) its timescale is approximately 5 min, (2) it is accompanied by strong magnetic fluctuations that have a dominant frequency close to the O+ gyrofrequency, (3) ion fluxes at 20–50 keV are simultaneously enhanced with larger magnitudes for O+ than for H+, (4) after a few minutes of the dipolarization, the flux enhancement at 0.1–5 keV appears with a clear energy-dispersion signature only for . . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022549 Available at: http://doi.wiley.com/10.1002/2016JA022549
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Authors: é M., Keika K, Kletzing C A, Spence H E, Smith C W, et al.
Title: Van Allen Probes observations of magnetic field dipolarization and its associated O + flux variations in the inner magnetosphere at L  < 6.6
Abstract: We investigate magnetic field dipolarization in the inner magnetosphere and its associated ion flux variations, using the magnetic field and energetic ion flux data acquired by the Van Allen Probes. From a study of 74 events that appeared at L = 4.5–6.6 between 1 October 2012 and 31 October 2013, we reveal the following characteristics of the dipolarization in the inner magnetosphere: (1) its timescale is approximately 5 min, (2) it is accompanied by strong magnetic fluctuations that have a dominant frequency close to the O+ gyrofrequency, (3) ion fluxes at 20–50 keV are simultaneously enhanced with larger magnitudes for O+ than for H+, (4) after a few minutes of the dipolarization, the flux enhancement at 0.1–5 keV appears with a clear energy-dispersion signature only for . . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022549 Available at: http://doi.wiley.com/10.1002/2016JA022549
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Authors: Usanova M. E., Malaspina D. M., Jaynes A. N., Bruder R. J., Mann I. R., et al.
Title: Van Allen Probes observations of oxygen cyclotron harmonic waves in the inner magnetosphere
Abstract: Waves with frequencies in the vicinity of the oxygen cyclotron frequency and its harmonics have been regularly observed on the Van Allen Probes satellites during geomagnetic storms. We focus on properties of these waves and present events from the main phase of two storms on 1 November 2012 and 17 March 2013 and associated dropouts of a few MeV electron fluxes. They are electromagnetic, in the frequency range ~0.5 to several Hz, and amplitude ~0.1 to a few nT in magnetic and ~0.1 to a few mV/m in electric field, with both the wave velocity and the Poynting vector directed almost parallel to the background magnetic field. These properties are very similar to those of electromagnetic ion cyclotron waves, which are believed to contribute to loss of ring current ions and radiation belt electro. . .
Date: 09/2016 Publisher: Geophysical Research Letters Pages: 8827 - 8834 DOI: 10.1002/grl.v43.1710.1002/2016GL070233 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL070233/abstract
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Authors: Fennell J. F., Claudepierre S G, Blake J B, O'Brien T P, Clemmons J. H., et al.
Title: Van Allen Probes show the inner radiation zone contains no MeV electrons: ECT/MagEIS data
Abstract: We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the ECT/MagEIS sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e. >0.1 electrons/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes <200 keV exceeded the AE9 model 50% fluxes and were lower than the higher energy model fluxes. Phase space density radial profiles for 1.3≤L*<2.5 had mostly positive gradients except near L*~2.1 where the profiles for μ = 20-30 MeV/G were flat or slightly peaked. The major result is that MagEIS data. . .
Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062874 Available at: http://doi.wiley.com/10.1002/2014GL062874
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Authors: Fennell J. F., Claudepierre S G, Blake J B, O'Brien T P, Clemmons J. H., et al.
Title: Van Allen Probes show the inner radiation zone contains no MeV electrons: ECT/MagEIS data
Abstract: We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the ECT/MagEIS sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e. >0.1 electrons/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes <200 keV exceeded the AE9 model 50% fluxes and were lower than the higher energy model fluxes. Phase space density radial profiles for 1.3≤L*<2.5 had mostly positive gradients except near L*~2.1 where the profiles for μ = 20-30 MeV/G were flat or slightly peaked. The major result is that MagEIS data. . .
Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062874 Available at: http://doi.wiley.com/10.1002/2014GL062874
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Authors: Fennell J. F., Claudepierre S G, Blake J B, O'Brien T P, Clemmons J. H., et al.
Title: Van Allen Probes show the inner radiation zone contains no MeV electrons: ECT/MagEIS data
Abstract: We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the ECT/MagEIS sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e. >0.1 electrons/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes <200 keV exceeded the AE9 model 50% fluxes and were lower than the higher energy model fluxes. Phase space density radial profiles for 1.3≤L*<2.5 had mostly positive gradients except near L*~2.1 where the profiles for μ = 20-30 MeV/G were flat or slightly peaked. The major result is that MagEIS data. . .
Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062874 Available at: http://doi.wiley.com/10.1002/2014GL062874
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Authors: Matsuda Shoya, Kasahara Yoshiya, and Kletzing Craig A.
Title: Variation in crossover frequency of EMIC waves in plasmasphere estimated from ion cyclotron whistler waves observed by Van Allen Probe A
Abstract: We report variations in the propagation of the H+ band ion cyclotron whistlers observed by Van Allen Probe A. Ion cyclotron whistlers are one of the EMIC (electromagnetic ion cyclotron) waves generated by mode conversion from lightning whistlers. Crossover frequency is an important frequency for the ion cyclotron whistlers, which is a function of the variations in the local heavy-ion composition. We surveyed waveform data obtained by the Electric and Magnetic Field Instrument and Integrated Science instrument and found that 3461 H+ band ion cyclotron whistlers were observed from 572 km to 5992 km in altitude. The main finding is that the crossover frequencies of the observed events decreased with increasing altitude. These results support the hypothesis that the total heavy-ion density dec. . .
Date: 01/2016 Publisher: Geophysical Research Letters Pages: 28 - 34 DOI: 10.1002/2015GL066893 Available at: http://doi.wiley.com/10.1002/2015GL066893
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Authors: Malaspina David M., Ripoll Jean-Francois, Chu Xiangning, Hospodarsky George, and Wygant John
Title: Variation in Plasmaspheric Hiss Wave Power With Plasma Density
Abstract: Plasmaspheric hiss waves are commonly observed in the inner magnetosphere. These waves efficiently scatter electrons, facilitating their precipitation into the atmosphere. Predictive inner magnetosphere simulations often model hiss waves using parameterized empirical maps of observed hiss power. These maps nearly always include parameterization by magnetic L value. In this work, data from the Van Allen Probes are used to compare variation in hiss wave power with variation in both L value and cold plasma density. It is found that for L> 2.5, plasmaspheric hiss wave power increases with plasma density. For L> 3, this increase is stronger and occurs regardless of L value and for all local times. This result suggests that the current paradigm for parameterizing hiss wave power in many magnetos. . .
Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078564 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078564
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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: Nakayama Y., Ebihara Y., Ohtani S, Gkioulidou M., Takahashi K., et al.
Title: Void structure of O + ions in the inner magnetosphere observed by the Van Allen Probes
Abstract: The Van Allen Probes Helium Oxygen Proton Electron instrument observed a new type of enhancement of O+ ions in the inner magnetosphere during substorms. As the satellite moved outward in the premidnight sector, the flux of the O+ ions with energy ~10 keV appeared first in the energy-time spectrograms. Then, the enhancement of the flux spread toward high and low energies. The enhanced flux of the O+ ions with the highest energy remained, whereas the flux of the ions with lower energy vanished near apogee, forming what we call the void structure. The structure cannot be found in the H+ spectrogram. We studied the generation mechanism of this structure by using numerical simulation. We traced the trajectories of O+ ions in the electric and magnetic fields from the global magnetohydrodynamic. . .
Date: 11/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023013 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023013/full
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Authors: Jahn J -M, Goldstein J, Reeves G D, Fernandes P. A., Skoug R M, et al.
Title: The Warm Plasma Composition in the Inner Magnetosphere during 2012-2015
Abstract: Ionospheric heavy ions play an important role in the dynamics of Earth's magnetosphere. The greater mass and gyro radius of ionospheric oxygen differentiates its behavior from protons at the same energies. Oxygen may have an impact on tail reconnection processes, and it can at least temporarily dominate the energy content of the ring current during geomagnetic storms. At sub-keV energies, multi-species ion populations in the inner magnetosphere form the warm plasma cloak, occupying the energy range between the plasmasphere and the ring current. Lastly, cold lighter ions from the mid-latitude ionosphere create the co-rotating plasmasphere whose outer regions can interact with the plasma cloak, plasma sheet, ring current, and outer electron belt. In this paper we present a statistical view o. . .
Date: 09/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024183 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024183/full
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Authors: Lejosne Solène, and Roederer Juan G.
Title: The “zebra stripes”: An effect of F-region zonal plasma drifts on the longitudinal distribution of radiation belt particles
Abstract: We examine a characteristic effect, namely, the ubiquitous appearance of structured peaks and valleys called zebra stripes in the spectrograms of energetic electrons and ions trapped in the inner belt below L ~ 3. We propose an explanation of this phenomenon as a purely kinematic consequence of particle drift velocity modulation caused by F region zonal plasma drifts in the ionosphere. In other words, we amend the traditional assumption that the electric field associated with ionospheric plasma drives trapped particle distributions into rigid corotation with the Earth. An equation based on a simple first-order model is set up to determine quantitatively the appearance of zebra stripes as a function of magnetic time. Our numerical predictions are in agreement with measurements by the Ra. . .
Date: 01/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021925 Available at: http://doi.wiley.com/10.1002/2015JA021925
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