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2018
Authors: Zhang Dianjun, Liu Wenlong, Li Xinlin, Sarris Theodore, Xiao Chao, et al.
Title: Observations of impulsive electric fields induced by Interplanetary Shock
Abstract: We investigate the characteristics of impulsive electric fields in Earth's magnetosphere, as measured by the Van Allen Probes, in association with interplanetary shocks, as measured by ACE and Wind spacecraft in the solar wind from January 2013 to July 2016. It is shown that electric field impulses are mainly induced by global compressions by the shocks, mostly in the azimuthal direction and the amplitudes of the initial electric field impulses are positively correlated with the rate of increase of dynamic pressure across the shock in the dayside. It is also shown that the temporal profile of the impulse is related to the temporal profile of the solar wind dynamic pressure, Pd. It is suggested that during the first period of the impulse the evolution of the electric field is directly contr. . .
Date: 07/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078809 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078809
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Authors: Zhang Zhenxia, Chen Lunjin, Li Xinqiao, Xia Zhiyang, Heelis Roderick A., et al.
Title: Observed propagation route of VLF transmitter signals in the magnetosphere
Abstract: Signals of powerful ground transmitters at various places have been detected by satellites in near‐Earth space. The study on propagation mode, ducted or nonducted, has attracted much attentions for several decades. Based on the statistical results from Van Allen Probes (data from Oct. 2012 to Mar. 2017) and DEMETER satellite (from Jan. 2006 to Dec. 2007), we present the ground transmitter signals distributed clearly in ionosphere and magnetosphere. The observed propagation route in the meridian plane in the magnetosphere for each of various transmitters from the combination of DEMETER and Van Allen Probes data in night time is revealed for the first time. We use realistic ray tracing simulation and compare simulation results against Van Allen Probes and DEMETER observation. By comparison. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025637 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025637
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Authors: Artemyev A. V., Zhang X.-J., Angelopoulos V, Runov A., Spence H E, et al.
Title: Plasma anisotropies and currents in the near-Earth plasma sheet and inner magnetosphere
Abstract: The region occupying radial distances of ∼3 − 9 Earth radii (RE) in the night side, includes the near‐Earth plasma sheet with stretched magnetic field lines and the inner magnetosphere with strong dipolar magnetic field. In this region, the plasma flow energy, which was injected into the inner magnetosphere from the magnetotail, is converted to particle heating and electromagnetic wave generation. These important processes are controlled by plasma anisotropies, which are the focus of this study. Using measurements of THEMIS and Van Allen Probes in this transition region we obtain radial profiles of ion and electron temperatures and anisotropies for various geomagnetic activity levels. Ion and electron anisotropies vary with the geomagnetic activity in opposite directions. Paralle. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025232 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025232
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Authors: Artemyev A. V., Zhang X.-J., Angelopoulos V, Runov A., Spence H E, et al.
Title: Plasma anisotropies and currents in the near-Earth plasma sheet and inner magnetosphere
Abstract: The region occupying radial distances of ∼3 − 9 Earth radii (RE) in the night side, includes the near‐Earth plasma sheet with stretched magnetic field lines and the inner magnetosphere with strong dipolar magnetic field. In this region, the plasma flow energy, which was injected into the inner magnetosphere from the magnetotail, is converted to particle heating and electromagnetic wave generation. These important processes are controlled by plasma anisotropies, which are the focus of this study. Using measurements of THEMIS and Van Allen Probes in this transition region we obtain radial profiles of ion and electron temperatures and anisotropies for various geomagnetic activity levels. Ion and electron anisotropies vary with the geomagnetic activity in opposite directions. Paralle. . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025232 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025232
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Authors: Yu Xiongdong, Yuan Zhigang, Li Haimeng, Huang Shiyong, Wang Dedong, et al.
Title: Response of banded whistler-mode waves to the enhancement of solar wind dynamic pressure in the inner Earth's magnetosphere
Abstract: With observations of Van Allen Probe A, in this letter we display a typical event where banded whistler waves shifted up their frequencies with frequency bands broadening as a response to the enhancement of solar wind dynamic pressure. Meanwhile, the anisotropy of electrons with energies about several tens of keV was observed to increase. Through the comparison of the calculated wave growth rates and observed wave spectral intensity, we suggest that those banded whistler waves observed with frequencies shifted up and frequency bands broadening could be locally excited by these hot electrons with increased anisotropy. The current study provides a great in situ evidence for the influence on frequencies of banded whistler waves by the enhancement of solar wind dynamic pressures, which reveals. . .
Date: Mar-08-2020 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078849 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078849
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Authors: Motoba T., Ohtani S, Gkioulidou M., Ukhorskiy A., Mitchell D G, et al.
Title: Response of Different Ion Species to Local Magnetic Dipolarization Inside Geosynchronous Orbit
Abstract: This paper examines how hydrogen, helium and oxygen (H, He and O) ion fluxes at 1–1000 keV typically respond to local magnetic dipolarization inside geosynchronous orbit (GEO). We extracted 144 dipolarizations which occurred at magnetic inclination > 30° from the 2012–2016 tail seasons' observations of the Van Allen Probes spacecraft and then defined typical flux changes of these ion species by performing a superposed epoch analysis. On average, the dipolarization inside GEO is accompanied by a precursory transient decrease in the northward magnetic field component, transient impulsive enhancement in the westward electric field component, and decrease (increase) in the proton density (temperature). The coincident ion species experience an energy‐dependent flux change, consisting of . . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025557 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025557
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Authors: Motoba T., Ohtani S, Gkioulidou M., Ukhorskiy A., Mitchell D G, et al.
Title: Response of Different Ion Species to Local Magnetic Dipolarization Inside Geosynchronous Orbit
Abstract: This paper examines how hydrogen, helium and oxygen (H, He and O) ion fluxes at 1–1000 keV typically respond to local magnetic dipolarization inside geosynchronous orbit (GEO). We extracted 144 dipolarizations which occurred at magnetic inclination > 30° from the 2012–2016 tail seasons' observations of the Van Allen Probes spacecraft and then defined typical flux changes of these ion species by performing a superposed epoch analysis. On average, the dipolarization inside GEO is accompanied by a precursory transient decrease in the northward magnetic field component, transient impulsive enhancement in the westward electric field component, and decrease (increase) in the proton density (temperature). The coincident ion species experience an energy‐dependent flux change, consisting of . . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025557 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025557
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Authors: Olifer L., Mann I. R., Morley S. K., Ozeke L. G., and Choi D.
Title: On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction
Abstract: We present observations of very fast radiation belt loss as resolved using high‐time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The timescale of these losses is revealed to be as short as ∼0.5 − 2 hours during intense magnetic storms, with some storms demonstrating almost total loss on these timescales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around two weeks. By contrast, the moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. We compute the last closed drift shell (LCDS) for each of these . . .
Date: 04/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025190 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025190
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Authors: Ohtani S, Motoba T., Gkioulidou M., Takahashi K., and Singer H J
Title: Spatial Development of the Dipolarization Region in the Inner Magnetosphere
Abstract: The present study examines dipolarization events observed by the Van Allen Probes within 5.8 RE from Earth. It is found that the probability of occurrence is significantly higher in the dusk‐to‐midnight sector than in the midnight‐to‐dawn sector, and it deceases sharply earthward. A comparison with observations made at nearby satellites shows that dipolarization signatures are often highly correlated (c.c. > 0.8) within 1 hr in MLT and 1 RE in RXY, and the dipolarization region expands earthward and westward in the dusk‐to‐midnight sector. The westward expansion velocity is estimated at 0.4 hr (in MLT) per minute, or 60 km/s, which is consistent with the previously reported result for geosynchronous dipolarization. The earthward expansion is apparently less systematic than the . . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025443 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025443
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Authors: Ohtani S, Motoba T., Gkioulidou M., Takahashi K., and Singer H J
Title: Spatial Development of the Dipolarization Region in the Inner Magnetosphere
Abstract: The present study examines dipolarization events observed by the Van Allen Probes within 5.8 RE from Earth. It is found that the probability of occurrence is significantly higher in the dusk‐to‐midnight sector than in the midnight‐to‐dawn sector, and it deceases sharply earthward. A comparison with observations made at nearby satellites shows that dipolarization signatures are often highly correlated (c.c. > 0.8) within 1 hr in MLT and 1 RE in RXY, and the dipolarization region expands earthward and westward in the dusk‐to‐midnight sector. The westward expansion velocity is estimated at 0.4 hr (in MLT) per minute, or 60 km/s, which is consistent with the previously reported result for geosynchronous dipolarization. The earthward expansion is apparently less systematic than the . . .
Date: 06/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025443 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025443
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Authors: Noh Sung-Jun, Lee Dae-Young, Choi Cheong-Rim, Kim Hyomin, and Skoug Ruth
Title: Test of Ion Cyclotron Resonance Instability Using Proton Distributions Obtained From Van Allen Probe-A Observations
Abstract: Anisotropic velocity distributions of protons have long been considered as free energy sources for exciting electromagnetic ion cyclotron (EMIC) waves in the Earth's magnetosphere. Here we rigorously calculated the proton anisotropy parameter using proton data obtained from Van Allen Probe‐A observations. The calculations are performed for times during EMIC wave events (distinguishing the times immediately after and before EMIC wave onsets) and for times exhibiting no EMIC waves. We find that the anisotropy values are often larger immediately after EMIC wave onsets than the times just before EMIC wave onsets and the non‐EMIC wave times. The increase in anisotropy immediately after the EMIC wave onsets is rather small but discernible, such that the average increase is by ~15% relative t. . .
Date: 08/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025385 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025385
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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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2019
Authors: Xu Jiyao, He Zhaohai, Baker D.N., Roth Ilan, Wang C., et al.
Title: Characteristics of high energy proton responses to geomagnetic activities in the inner radiation belt observed by the RBSP satellite
Abstract: High energy trapped particles in the radiation belts constitute potential threats to the functionality of satellites as they enter into those regions. In the inner radiation belt, the characteristics of high‐energy (>20MeV) protons variations during geomagnetic activity times have been studied by implementing four‐year (2013‐2016) observations of the Van Allen probes. An empirical formula has been used to remove the satellite orbit effect, by which proton fluxes have been normalized to the geomagnetic equator. Case studies show that the region of L<1.7 is relatively stable, while L>1.7 is more dynamic and the most significant variation of proton fluxes occurs at L=2.0. The four‐year survey at L=2.0 indicates that for every geomagnetic storm, sharp descent in proton fluxes is accomp. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026205 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026205
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Authors: Omura Yoshiharu, Hsieh Yi‐Kai, Foster John C., Erickson Philip J., Kletzing Craig A., et al.
Title: Cyclotron Acceleration of Relativistic Electrons Through Landau Resonance With Obliquely Propagating Whistler‐Mode Chorus Emissions
Abstract: Efficient acceleration of relativistic electrons at Landau resonance with obliquely propagating whistler‐mode chorus emissions is confirmed by theory, simulation, and observation. The acceleration is due to the perpendicular component of the wave electric field. We first review theoretical analysis of nonlinear motion of resonant electrons interacting with obliquely propagating whistler‐mode chorus. We have derived formulae of inhomogeneity factors for Landau and cyclotron resonances to analyze nonlinear wave trapping of energetic electrons by an obliquely propagating chorus element. We performed test particle simulations to confirm that nonlinear wave trapping by both Landau and cyclotron resonances can take place for a wide range of energies. For an element of large amplitude chorus . . .
Date: 04/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026374 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026374
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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: 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: 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: Ma Q, Li W, Yue C., Thorne R M, Bortnik J, et al.
Title: Ion Heating by Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves in the Earth's Inner Magnetosphere
Abstract: Electromagnetic ion cyclotron (EMIC) waves and magnetosonic waves are commonly observed in the Earth's magnetosphere associated with enhanced ring current activity. Using wave and ion measurements from the Van Allen Probes, we identify clear correlations between the hydrogen‐ and helium‐band EMIC waves with the enhancement of trapped helium and oxygen ion fluxes, respectively. We calculate the diffusion coefficients of different ion species using quasi‐linear theory to understand the effects of resonant scattering by EMIC waves. Our calculations indicate that EMIC waves can cause pitch angle scattering loss of several keV to hundreds of keV ions, and heating of tens of eV to several keV helium and oxygen ions by hydrogen‐ and helium‐band EMIC waves, respectively. Moreover, we fou. . .
Date: 06/2019 Publisher: Geophysical Research Letters Pages: 6258 - 6267 DOI: 10.1029/2019GL083513 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083513
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Authors: Gkioulidou Matina, Ohtani S, Ukhorskiy A Y, Mitchell D G, Takahashi K., et al.
Title: Low-Energy (+ Ion Outflow Directly Into the Inner Magnetosphere: Van Allen Probes Observations
Abstract: The heavy ion component of the low‐energy (eV to hundreds of eV) ion population in the inner magnetosphere, also known as the O+ torus, is a crucial population for various aspects of magnetospheric dynamics. Yet even though its existence has been known since the 1980s, its formation remains an open question. We present a comprehensive study of a low‐energy (Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics Pages: 405 - 419 DOI: 10.1029/2018JA025862 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025862
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Authors: Wei Chao, Dai Lei, Duan Suping, Wang Chi, Wang YuXian, et al.
Title: Multiple satellites observation evidence: High-m Poloidal ULF waves with time-varying polarization states
Abstract: We report multi‐spacecraft observations of ULF waves from Van Allen Probes (RBSP), Magnetospheric Multiscale (MMS), Time History of Events and Macroscale Interactions during Substorm (THEMIS), and Geostationary Operational Environmental Satellites (GOES). On August 31, 2015, global‐scale poloidal waves were observed in data from RBSP‐B, GOES and THEMIS from L=4 to L=8 over a wide range of magnetic local time (MLT). The polarization states varied towards purely poloidal polarity. In two consecutive orbits over 18 hours, RBSP‐A and RBSP‐B recorded gradual variation of the polarization states of the poloidal waves; the ratio (|Ba|/|Br|) decreased from 0.82 to 0.13. After the variation of polarization states, the poloidal ULF waves became very purely poloidal waves, localized in both. . .
Date: 05/2019 Publisher: Earth and Planetary Physics Pages: 190 - 203 DOI: 10.26464/epp2019021 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.26464/epp2019021
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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: 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: Aseev N. A., and Shprits Y Y
Title: Reanalysis of Ring Current Electron Phase Space Densities Using Van Allen Probe Observations, Convection Model, and Log‐Normal Kalman Filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting . . .
Date: 04/2019 Publisher: Space Weather Pages: 619 - 638 DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
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Authors: Aseev N.A., and Shprits Y.Y.
Title: Reanalysis of ring current electron phase space densities using Van Allen Probe observations, convection model, and log‐normal Kalman filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting erro. . .
Date: 04/2019 Publisher: Space Weather DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
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Authors: Turner D. L., Kilpua E. K. J., Hietala H., Claudepierre S G, O'Brien T P, et al.
Title: The Response of Earth's Electron Radiation Belts to Geomagnetic Storms: Statistics From the Van Allen Probes Era Including Effects From Different Storm Drivers
Abstract: A statistical study was conducted of Earth's radiation belt electron response to geomagnetic storms using NASA's Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L‐shell, energy, and epoch time during 110 storms with SYM‐H ≤−50 nT during September 2012 to September 2017 (inclusive). The radiation belt response revealed clear energy and L‐shell dependencies, with tens of keV electrons enhanced at all L‐shells (2.5 ≤ L ≤ 6) in all storms during the storm commencement and main phase and then quickly decaying away during the early recovery phase, low hundreds of keV electrons enhanced at lower L‐shells (~3 ≤ L ≤ ~4) in upward of 90% of all storms and then decaying gradually during the rec. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026066 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026066
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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: 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: 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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