Biblio

Found 879 results
2015
Authors: Spasojevic M., Shprits Y.Y., and Orlova K.
Title: Global Empirical Models of Plasmaspheric Hiss using Van Allen Probes
Abstract: Plasmaspheric hiss is a whistler mode emission that permeates the Earth's plasmasphere and is a significant driver of energetic electron losses through cyclotron-resonant pitch angle scattering. The EMFISIS instrument on the Van Allen Probes mission provides vastly improved measurements of the hiss wave environment including continuous measurements of the wave magnetic field cross-spectral matrix and enhanced low frequency coverage. Here, we develop empirical models of hiss wave intensity using two years of Van Allen Probes data. First, we describe the construction of the hiss database. Then, we compare the hiss spectral distribution and integrated wave amplitude obtained from Van Allen Probes to those previously extracted from the CRRES mission. Next, we develop a cubic regression model o. . .
Date: 11/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021803 Available at: http://doi.wiley.com/10.1002/2015JA021803http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021803
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Authors: Ukhorskiy A Y, Sitnov M I, Millan R M, Kress B T, Fennell J. F., et al.
Title: Global Storm-Time Depletion of the Outer Electron Belt
Abstract: The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by ordersof magnitude at different spatial and temporal scale. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase depletions: adiabatic inflation of electron drift orbits caused by the ring current growth, electron loss into the atmosphere, and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the adiabatic effect and magnetopause . . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020645 Available at: http://doi.wiley.com/10.1002/2014JA020645
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Authors: Breneman A. W., Halford A., Millan R., McCarthy M., Fennell J, et al.
Title: Global-scale coherence modulation of radiation-belt electron loss from plasmaspheric hiss
Abstract: Over 40 years ago it was suggested that electron loss in the region of the radiation belts that overlaps with the region of high plasma density called the plasmasphere, within four to five Earth radii1, 2, arises largely from interaction with an electromagnetic plasma wave called plasmaspheric hiss3, 4, 5. This interaction strongly influences the evolution of the radiation belts during a geomagnetic storm, and over the course of many hours to days helps to return the radiation-belt structure to its ‘quiet’ pre-storm configuration. Observations have shown that the long-term electron-loss rate is consistent with this theory but the temporal and spatial dynamics of the loss process remain to be directly verified. Here we report simultaneous measurements of structured radiation-belt electr. . .
Date: 06/2015 Publisher: Nature Pages: 193 - 195 DOI: 10.1038/nature14515 Available at: http://www.nature.com/doifinder/10.1038/nature14515
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Authors: Ferradas C. P., Zhang J.-C., Kistler L. M., and Spence H E
Title: Heavy-ion dominance near Cluster perigees
Abstract: Time periods in which heavy ions dominate over H+ in the energy range of 1-40 keV were observed by the Cluster Ion Spectrometry (CIS)/COmposition DIstribution Function (CODIF) instrument onboard Cluster Spacecraft 4 at L-values less than 4. The characteristic feature is a narrow flux peak at around 10 keV that extends into low L-values, with He+ and/or O+ dominating. In the present work we perform a statistical study of these events and examine their temporal occurrence and spatial distribution. The observed features, both the narrow energy range and the heavy-ion dominance, can be interpreted using a model of ion drift from the plasma sheet, subject to charge exchange losses. The narrow energy range corresponds to the only energy range that has direct drift access from the plasma sheet du. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021063 Available at: http://doi.wiley.com/10.1002/2015JA021063http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021063
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Authors: Selesnick R. S.
Title: High-energy radiation belt electrons from CRAND
Abstract: A calculation of the inner radiation belt electron source from cosmic ray albedo neutron decay (CRAND) is described. High-energy electrons are included by Lorentz-transforming the β decay spectrum from the neutron rest frame to the Earth's rest frame and combining with the known high-energy albedo neutron energy spectrum. Balancing the electron source with energy loss to atmospheric neutral atoms and plasma, and with a decay lifetime representative of plasma wave scattering, then provides an estimate of trapped electron intensity. It is well below measured values for low energies, confirming that CRAND is not a significant source of those trapped electrons. For kinetic energies above the maximum β decay energy (E > 0.8 MeV) a power law energy spectrum ∼E−4 is predicted. For L = 1.5. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020963 Available at: http://doi.wiley.com/10.1002/2014JA020963
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Authors: Rodger Craig J., Hendry Aaron T., Clilverd Mark A., Kletzing Craig A., Brundell James B., et al.
Title: High-resolution in situ observations of electron precipitation-causing EMIC waves
Abstract: Electromagnetic ion cyclotron (EMIC) waves are thought to be important drivers of energetic electron losses from the outer radiation belt through precipitation into the atmosphere. While the theoretical possibility of pitch angle scattering-driven losses from these waves has been recognized for more than four decades, there have been limited experimental precipitation observations to support this concept. We have combined satellite-based observations of the characteristics of EMIC waves, with satellite and ground-based observations of the EMIC-induced electron precipitation. In a detailed case study, supplemented by an additional four examples, we are able to constrain for the first time the location, size, and energy range of EMIC-induced electron precipitation inferred from coincident pr. . .
Date: 11/2015 Publisher: Geophysical Research Letters Pages: 9633 - 9641 DOI: 10.1002/grl.v42.2210.1002/2015GL066581 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL066581/full
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Authors: Titova E. E., Kozelov B. V., Demekhov A. G., Manninen J., Santolik O, et al.
Title: Identification of the source of quasiperiodic VLF emissions using ground-based and Van Allen Probes satellite observations
Abstract: We report on simultaneous spacecraft and ground-based observations of quasiperiodic VLF emissions and related energetic-electron dynamics. Quasiperiodic emissions in the frequency range 2–6 kHz were observed during a substorm on 25 January 2013 by Van Allen Probe-A and a ground-based station in the Northern Finland. The spacecraft detected the VLF signals near the geomagnetic equator in the night sector at L = 3.0–4.2 when it was inside the plasmasphere. During the satellite motion toward higher latitudes, the time interval between quasiperiodic elements decreased from 6 min to 3 min. We find one-to-one correspondence between the quasiperiodic elements detected by Van Allen Probe-A and on the ground, which indicates the temporal nature of the observed variation in the time in. . .
Date: 08/2015 Publisher: Geophysical Research Letters Pages: 6137 - 6145 DOI: 10.1002/grl.v42.1510.1002/2015GL064911 Available at: http://doi.wiley.com/10.1002/2015GL064911
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Authors: Zhou Xu-Zhi, Wang Zi-Han, Zong Qiu-Gang, Claudepierre Seth G., Mann Ian R., et al.
Title: Imprints of impulse-excited hydromagnetic waves on electrons in the Van Allen radiation belts
Abstract: Ultralow frequency electromagnetic oscillations, interpreted as standing hydromagnetic waves in the magnetosphere, are a major energy source that accelerates electrons to relativistic energies in the Van Allen radiation belt. Electrons can rapidly gain energy from the waves when they resonate via a process called drift resonance, which is observationally characterized by energy-dependent phase differences between electron flux and electromagnetic oscillations. Such dependence has been recently observed and interpreted as spacecraft identifications of drift resonance electron acceleration. Here we show that in the initial wave cycles, the observed phase relationship differs from that characteristic of well-developed drift resonance. We further examine the differences and find that they are . . .
Date: 08/2015 Publisher: Geophysical Research Letters Pages: 6199 - 6204 DOI: 10.1002/grl.v42.1510.1002/2015GL064988 Available at: http://doi.wiley.com/10.1002/grl.v42.15http://doi.wiley.com/10.1002/2015GL064988
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Authors: Yu Xiongdong, Yuan Zhigang, Wang Dedong, Li Haimeng, Huang Shiyong, et al.
Title: In situ observations of EMIC waves in O + band by the Van Allen Probe A
Abstract: Through polarization and spectra analysis of the magnetic field observed by the Van Allen Probe A, we present two typical cases of O+ band EMIC waves in the outer plasmasphere or plasma trough. Although such O+ band EMIC waves are rarely observed, 18 different events of O+ band EMIC waves (16 events in the outer plasmasphere and 2 events in the plasma trough) are found from September 2012 to August 2014 with observations of the Van Allen Probe A. We find that the preferred region for the occurrence of O+ band EMIC waves is in L = 2-5 and MLT = 03-13, 19-20, which is in accordance with the occurrence region of O+ ion torus. Therefore, our result suggests that the O+ ion torus in the outer plasmasphere during geomagnetic activities should play an important role in the generation of EMIC wave. . .
Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL063250 Available at: http://doi.wiley.com/10.1002/2015GL063250
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Authors: Srinivasan Dipak K., Adams Norm, and Wallis Robert
Title: In-flight performance of the Van Allen Probes RF telecommunications system
Abstract: The NASA Van Allen Probes mission (previously called the Radiation Belt Storm Probes) successfully launched on 30 August 2012. The twin spacecraft, designed, built, and operated by The Johns Hopkins University Applied Physics Laboratory (JHU/APL), has been successfully operating within Earth׳s radiation belts since then, returning critical science data revealing new insights into the physics of the radiation belts. Because of the extreme radiation environment, all spacecraft subsystems including the communications system had to make special accommodations to withstand the effects of the radiation. Each Van Allen Probes spacecraft׳s telecommunications system includes an S-band version of the Frontier Radio, a solid-state power amplifier, RF routing components, and dual low-gain antenna. . .
Date: 11/2015 Publisher: Acta Astronautica Pages: 211 - 221 DOI: 10.1016/j.actaastro.2015.05.001 Available at: http://www.sciencedirect.com/science/article/pii/S0094576515001824
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Authors: Němec F., Santolik O, Hrbáčková Z., and Cornilleau-Wehrlin N.
Title: Intensities and spatiotemporal variability of equatorial noise emissions observed by the Cluster spacecraft
Abstract: Equatorial noise (EN) emissions are electromagnetic waves observed in the equatorial region of the inner magnetosphere at frequencies between the proton cyclotron frequency and the lower hybrid frequency. We present the analysis of 2229 EN events identified in the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment data of the Cluster spacecraft during the years 2001–2010. EN emissions are distinguished using the polarization analysis, and their intensity is determined based on the evaluation of the Poynting flux rather than on the evaluation of only the electric/magnetic field intensity. The intensity of EN events is analyzed as a function of the frequency, the position of the spacecraft inside/outside the plasmasphere, magnetic local time, and the geomagnetic activity. Th. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 1620 - 1632 DOI: 10.1002/2014JA020814 Available at: http://doi.wiley.com/10.1002/2014JA020814
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Authors: Skov Tamitha Mulligan, Fennell Joseph F., Roeder James L., Blake Bernard, and Claudepierre Seth G.
Title: Internal Charging Hazards in Near-Earth Space During Solar Cycle 24 Maximum: Van Allen Probes Measurements
Abstract: The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. The MagEIS suite of sensors measures energy spectra and fluxes of charged particles in the space environment. The calculations show that these fluxes result in electron deposition rates high enough to cause internal charging. We use omnidirectional fluxes of electrons and protons to calculate the dose under varying materials and thicknesses of shielding. We show examples of charge deposition rates during the times of nominal and high levels of penetrating fluxes in the inner magnetosphere covering the period from the beginning of 2013 through mid-2014. These charge deposition rates are related . . .
Date: 09/2015 Publisher: IEEE Transactions on Plasma Science Pages: 3070 - 3074 DOI: 10.1109/TPS.2015.2468214 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=7247811http://xplorestaging.ieee.org/ielx7/27/7247791/07247811.pdf?arnumber=7247811
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Authors: Skov Mulligan, Fennell J.F., Roeder J.L., Blake J.B., and Claudepierre S.G.
Title: Internal Charging Hazards in Near-Earth Space during Solar Cycle 24 Maximum: Van Allen Probes Measurements
Abstract: The Van Allen Probes mission provides an unprecedented opportunity to make detailed measurements of electrons and protons in the inner magnetosphere during the weak solar maximum period of cycle 24. Data from the MagEIS suite of sensors measures energy spectra, fluxes, and yields electron deposition rates that can cause internal charging. We use omni-directional fluxes of electrons and protons to calculate the dose under varying materials and thicknesses of shielding (similar to Fennell et al., 2010). We show examples of charge deposition rates during times of nominal and high levels of penetrating fluxes in the inner magnetosphere covering the period from late 2012 through 2013. These charge deposition rates are related to charging levels quite possibly encountered. . .
Date: 09/2015 Publisher: JPL DOI: 10.1109/TPS.2015.2468214 Available at: http://ieeexplore.ieee.org/document/7247811/?reload=true&arnumber=7247811
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Authors: Malaspina David M., Claudepierre Seth G., Takahashi Kazue, Jaynes Allison N., Elkington Scot R, et al.
Title: Kinetic Alfvén Waves and Particle Response Associated with a Shock-Induced, Global ULF Perturbation of the Terrestrial Magnetosphere
Abstract: On 2 October 2013, the arrival of an interplanetary shock compressed the Earth's magnetosphere and triggered a global ULF (ultra low frequency) oscillation. The Van Allen Probe B spacecraft observed this large-amplitude ULF wave in situ with both magnetic and electric field data. Broadband waves up to approximately 100 Hz were observed in conjunction with, and modulated by, this ULF wave. Detailed analysis of fields and particle data reveals that these broadband waves are Doppler-shifted kinetic Alfvén waves. This event suggests that magnetospheric compression by interplanetary shocks can induce abrupt generation of kinetic Alfvén waves over large portions of the inner magnetosphere, potentially driving previously unconsidered wave-particle interactions throughout the inner magnetosphere. . .
Date: 11/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL065935 Available at: http://doi.wiley.com/10.1002/2015GL065935http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL065935
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Authors: Tejero E. M., Crabtree C., Blackwell D. D., Amatucci W. E., Mithaiwala M., et al.
Title: Laboratory studies of nonlinear whistler wave processes in the Van Allen radiation belts
Abstract: Important nonlinear wave-wave and wave-particle interactions that occur in the Earth’s Van Allen radiation belts are investigated in a laboratory experiment. Predominantly electrostatic waves in the whistler branch are launched that propagate near the resonance cone with measured wave normal angle greater than 85º. When the pump amplitude exceeds a threshold ~5 x10^6 times the back- ground magnetic field, wave power at frequencies below the pump frequency is observed at wave normal angles (~55º). The scattered wave has a perpendicular wavelength that is nearly an order of magnitude larger than that of the pump wave. Occasionally, the parametric decay of a lower hybrid wave into a magnetosonic wave and a whistler wave is simultaneously observed with a threshold of δB=B_0 ~7 x 10^-7. . .
Date: 08/2015 Publisher: Physics of Plasmas DOI: 10.1063/1.4928944 Available at: http://scitation.aip.org/content/aip/journal/pop/22/9/10.1063/1.4928944
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Authors: Tejero E. M., Crabtree C., Blackwell D. D., Amatucci W. E., Mithaiwala M., et al.
Title: Laboratory studies of nonlinear whistler wave processes in the Van Allen radiation belts
Abstract: Important nonlinear wave-wave and wave-particle interactions that occur in the Earth's Van Allen radiation belts are investigated in a laboratory experiment. Predominantly electrostatic waves in the whistler branch are launched that propagate near the resonance cone with measured wave normal angle greater than 85° . When the pump amplitude exceeds a threshold ∼5×10−6 times the background magnetic field, wave power at frequencies below the pump frequency is observed at wave normal angles (∼55°) . The scattered wave has a perpendicular wavelength that is nearly an order of magnitude larger than that of the pump wave. Occasionally, the parametric decay of a lower hybrid wave into a magnetosonic wave and a whistler wave is simultaneously observed with a threshold of δB/B0∼7×10−7. . .
Date: 09/2015 Publisher: Physics of Plasmas Pages: 091503 DOI: 10.1063/1.4928944 Available at: http://scitation.aip.org/content/aip/journal/pop/22/9/10.1063/1.4928944
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Authors: Motoba T., Takahashi K., Ukhorskiy A., Gkioulidou M., Mitchell D G, et al.
Title: Link between pre-midnight second harmonic poloidal waves and auroral undulations: Conjugate observations with a Van Allen Probes spacecraft and a THEMIS all-sky imager
Abstract: We report, for the first time, an auroral undulation event on 1 May 2013 observed by an all-sky imager (ASI) at Athabasca (L = 4.6), Canada, for which in situ field and particle measurements in the conjugate magnetosphere were available from a Van Allen Probes spacecraft. The ASI observed a train of auroral undulation structures emerging spontaneously in the pre-midnight subauroral ionosphere, during the growth phase of a substorm. The undulations had an azimuthal wavelength of ~180 km and propagated westward at a speed of 3–4 km s−1. The successive passage over an observing point yielded quasi-periodic oscillations in diffuse auroral emissions with a period of ~40 s. The azimuthal wave number m of the auroral luminosity oscillations was found to be m ~ −103. During the event the spa. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020863 Available at: http://doi.wiley.com/10.1002/2014JA020863
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Authors: Shue Jih-Hong, Hsieh Yi-Kai, Tam Sunny W. Y., Wang Kaiti, Fu Hui Shan, et al.
Title: Local time distributions of repetition periods for rising tone lower band chorus waves in the magnetosphere
Abstract: Whistler mode chorus waves generally occur outside the plasmapause in the magnetosphere. The most striking feature of the waves is their occurrence in discrete elements. One of the parameters that describe the discrete elements is the repetition period (Trp), the time between consecutive elements. The Trp has not been studied statistically before. We use high-resolution waveform data to derive distributions of Trp for different local times. We find that the average Trp for the nightside (0.56 s) and dawnside (0.53 s) are smaller than those for the dayside (0.81 s) and duskside (0.97 s). Through a comparison with the background plasma and magnetic fields, we also find that the total magnetic field and temperature are the main controlling factors that affect the variability of Trp. These res. . .
Date: 10/2015 Publisher: Geophysical Research Letters Pages: 8294 - 8301 DOI: 10.1002/2015GL066107 Available at: http://doi.wiley.com/10.1002/2015GL066107http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL066107
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Authors: Neal Jason J., Rodger Craig J., Clilverd Mark A., Thomson Neil R., Raita Tero, et al.
Title: Long-term determination of energetic electron precipitation into the atmosphere from AARDDVARK subionospheric VLF observations
Abstract: We analyze observations of subionospherically propagating very low frequency (VLF) radio waves to determine outer radiation belt energetic electron precipitation (EEP) flux magnitudes. The radio wave receiver in Sodankylä, Finland (Sodankylä Geophysical Observatory) observes signals from the transmitter with call sign NAA (Cutler, Maine). The receiver is part of the Antarctic-Arctic Radiation-belt Dynamic Deposition VLF Atmospheric Research Konsortia (AARDDVARK). We use a near-continuous data set spanning November 2004 until December 2013 to determine the long time period EEP variations. We determine quiet day curves over the entire period and use these to identify propagation disturbances caused by EEP. Long Wave Propagation Code radio wave propagation modeling is used to estimate the p. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020689 Available at: http://doi.wiley.com/10.1002/2014JA020689
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Authors: Posch J. L, Engebretson M. J., Olson C. N., Thaller S. A., Breneman A. W., et al.
Title: Low-harmonic magnetosonic waves observed by the Van Allen Probes
Abstract: Purely compressional electromagnetic waves (fast magnetosonic waves), generated at multiple harmonics of the local proton gyrofrequency, have been observed by various types of satellite instruments (fluxgate and search coil magnetometers and electric field sensors), but most recent studies have used data from search coil sensors, and many have been restricted to high harmonics. We report here on a survey of low-harmonic waves, based on electric and magnetic field data from the EFW double probe and EMFISIS fluxgate magnetometer instruments, respectively, on the Van Allen Probes spacecraft during its first full precession through all local times, from October 1, 2012 through July 13, 2014. These waves were observed both inside and outside the plasmapause (PP), at L shells from 2.4 to ~6 (the. . .
Date: 07/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021179 Available at: http://doi.wiley.com/10.1002/2015JA021179
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Authors: Vasko I. Y., Agapitov O. V., Mozer F, Artemyev A. V., and Jovanovic D.
Title: Magnetic field depression within electron holes
Abstract: We analyze electron holes that are spikes of the electrostatic field (up to 500 mV/m) observed by Van Allen Probes in the outer radiation belt. The unexpected feature is the magnetic field depression of about several tens of picotesla within many of the spikes. The earlier observations showed amplification or negligible perturbations of the magnetic field within the electron holes. We suggest that the observed magnetic field depression is due to the diamagnetic current of hot and highly anisotropic population of electrons trapped within the electron holes. The required trapped population should have a density up to 65% of the background plasma density, a temperature up to several keV, and a temperature anisotropy T⊥/T∥∼2. We argue that the observed electron holes could be generated. . .
Date: 04/2015 Publisher: Geophysical Research Letters Pages: 2123 - 2129 DOI: 10.1002/2015GL063370 Available at: http://doi.wiley.com/10.1002/2015GL063370
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Authors: Ali Ashar F., Elkington Scot R, Tu Weichao, Ozeke Louis G., Chan Anthony A, et al.
Title: Magnetic field power spectra and magnetic radial diffusion coefficients using CRRES magnetometer data
Abstract: We used the fluxgate magnetometer data from Combined Release and Radiation Effects Satellite (CRRES) to estimate the power spectral density (PSD) of the compressional component of the geomagnetic field in the ∼1 mHz to ∼8 mHz range. We conclude that magnetic wave power is generally higher in the noon sector for quiet times with no significant difference between the dawn, dusk, and the midnight sectors. However, during high Kp activity, the noon sector is not necessarily dominant anymore. The magnetic PSDs have a very distinct dependence on Kp. In addition, the PSDs appear to have a weak dependence on McIlwain parameter L with power slightly increasing as L increases. The magnetic wave PSDs are used along with the Fei et al. (2006) formulation to compute inline image as a function of L . . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020419 Available at: http://doi.wiley.com/10.1002/2014JA020419
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Authors: Paral J., Hudson M K, Kress B T, Wiltberger M. J., Wygant J R, et al.
Title: Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013
Abstract: Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW) electric field instrument on th. . .
Date: 08/2015 Publisher: Annales Geophysicae Pages: 1037 - 1050 DOI: 10.5194/angeo-33-1037-2015 Available at: http://www.ann-geophys.net/33/1037/2015/angeo-33-1037-2015.pdf
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Authors: Selesnick R. S.
Title: Measurement of inner radiation belt electrons with kinetic energy above 1 MeV
Abstract: Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992–2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electrons above 1 MeV following the 2003 Halloween storm injection, though they may have been present. However, by restricting data to a less-stable, low-altitude trapping region, a persistent presence of inner belt electrons in the energy range 1 to 1.6 MeV is demonstrated. Their soft. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 8339 - 8349 DOI: 10.1002/2015JA021387 Available at: http://doi.wiley.com/10.1002/2015JA021387http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021387
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Authors: Hudson M K, Paral J., Kress B T, Wiltberger M., Baker D N, et al.
Title: Modeling CME-shock driven storms in 2012 - 2013: MHD-test particle simulations
Abstract: The Van Allen Probes spacecraft have provided detailed observations of the energetic particles and fields environment for CME-shock driven storms in 2012 to 2013 which have now been modeled with MHD-test particle simulations. The Van Allen Probes orbital plane longitude moved from the dawn sector in 2012 to near midnight and pre-noon for equinoctial storms of 2013, providing particularly good measurements of the inductive electric field response to magnetopause compression for the 8 October 2013 CME-shock driven storm. An abrupt decrease in the outer boundary of outer zone electrons coincided with inward motion of the magnetopause for both 17 March and 8 October 2013 storms, as was the case for storms shortly after launch (Hudson et al., 2014). Modeling magnetopause dropout events in 2013 . . .
Date: 01/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020833 Available at: http://doi.wiley.com/10.1002/2014JA020833
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Authors: Ma Q, Li W, Thorne R M, Ni B, Kletzing C A, et al.
Title: Modeling inward diffusion and slow decay of energetic electrons in the Earth's outer radiation belt
Abstract: A new 3D diffusion code is used to investigate the inward intrusion and slow decay of energetic radiation belt electrons (>0.5 MeV) observed by the Van Allen Probes during a 10-day quiet period in March 2013. During the inward transport the peak differential electron fluxes decreased by approximately an order of magnitude at various energies. Our 3D radiation belt simulation including radial diffusion and pitch angle and energy diffusion by plasmaspheric hiss and Electromagnetic Ion Cyclotron (EMIC) waves reproduces the essential features of the observed electron flux evolution. The decay timescales and the pitch angle distributions in our simulation are consistent with the Van Allen Probes observations over multiple energy channels. Our study suggests that the quiet-time energetic electro. . .
Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062977 Available at: http://doi.wiley.com/10.1002/2014GL062977
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Authors: Yu Yiqun, Jordanova Vania, Zou Shasha, Heelis Roderick, Ruohoniemi Mike, et al.
Title: Modeling sub-auroral polarization streams (SAPS) during the March 17, 2013 storm
Abstract: The sub-auroral polarization streams (SAPS) are one of the most important features in representing magnetosphere-ionosphere coupling processes. In this study, we use a state-of-the-art modeling framework that couples an inner magnetospheric ring current model RAM-SCB with a global MHD model BATS-R-US and an ionospheric potential solver to study the SAPS that occurred during the March 17, 2013 storm event as well as to assess the modeling capability. Both ionospheric and magnetospheric signatures associated with SAPS are analyzed to understand the spatial and temporal evolution of the electrodynamics in the mid-latitude regions. Results show that the model captures the SAPS at sub-auroral latitudes, where Region-2 field-aligned currents (FACs) flow down to the ionosphere and the conductance. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020371 Available at: http://doi.wiley.com/10.1002/2014JA020371
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Authors: Takahashi Kazue, Waters Colin, Glassmeier Karl-Heinz, Kletzing Craig, Kurth William, et al.
Title: Multifrequency compressional magnetic field oscillations and their relation to multiharmonic toroidal mode standing Alfvén waves
Abstract: The power spectrum of the compressional component of magnetic fields observed by the Van Allen Probes spacecraft near the magnetospheric equator in the dayside plasmasphere sometimes exhibits regularly spaced multiple peaks at frequencies below 50 mHz. We show by detailed analysis of events observed on two separate days in early 2014 that the frequencies change smoothly with the radial distance of the spacecraft and appear at or very near the frequencies of the odd harmonics of mutiharmonic toroidal mode standing Alfvén waves seen in the azimuthal component of the magnetic field. Even though the compressional component had a low amplitude on one of the selected days, its spectral properties are highlighted by computing the ratio of the spectral powers of time series data obtained from two. . .
Date: 11/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021780 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015JA021780/abstract
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Authors: Yu J., Li L.Y., Cao J. B., Yuan Z. G., Reeves G D, et al.
Title: Multiple loss processes of relativistic electrons outside the heart of outer radiation belt during a storm sudden commencement
Abstract: By examining the compression-induced changes in the electron phase space density and pitch angle distribution observed by two satellites of Van Allen Probes (RBSP-A/B), we find that the relativistic electrons (>2MeV) outside the heart of outer radiation belt (L*≥ 5) undergo multiple losses during a storm sudden commencement (SSC). The relativistic electron loss mainly occurs in the field-aligned direction (pitch angle α< 30° or >150°), and the flux decay of the field-aligned electrons is independent of the spatial location variations of the two satellites. However, the relativistic electrons in the pitch angle range of 30°-150° increase (decrease) with the decreasing (increasing) geocentric distance (|ΔL|< 0.25) of the RBSP-B (RBSP-A) location, and the electron fluxes in the quasi-. . .
Date: 11/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021460 Available at: http://doi.wiley.com/10.1002/2015JA021460http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021460
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Authors: Dixon P., MacDonald E A, Funsten H O, Glocer A., Grande M., et al.
Title: Multipoint observations of the open-closed field line boundary as observed by the Van Allen Probes and geostationary satellites during the November 14 th 2012 geomagnetic storm
Abstract: The twin Van Allen Probes spacecraft witnessed a series of lobe encounters between 0200 and 0515 UT on November 14th 2012. Although lobe entry had been observed previously by the other spacecraft, the two Van Allen Probe spacecraft allow us to observe the motion of the boundary for the first time. Moreover, this event is unique in that it consists of a series of six quasi-periodic lobe entries. The events occurred on the dawn flank between 4 and 6.6 local time and at altitudes between 5.6 and 6.2 RE. During the events Dst dropped to less than -100nT with the IMF being strongly southward (Bz = −15nT) and eastward (By = 20 nT). Observations by LANL GEO spacecraft at geosynchronous orbit also show lobe encounters in the northern hemisphere and on the dusk flank. The two spacecraf. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020883 Available at: http://doi.wiley.com/10.1002/2014JA020883
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Authors: Dai Lei, Wang Chi, Duan Suping, He Zhaohai, Wygant John R., et al.
Title: Near-Earth Injection of MeV Electrons associated with Intense Dipolarization Electric Fields: Van Allen Probes observations
Abstract: Substorms generally inject 10s-100s keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the pre-midnight sector at L∼5.5, Van Allen Probes (RBSP)-A observed a large dipolarization electric field (50mV/m) over ∼40s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the in. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064955 Available at: http://doi.wiley.com/10.1002/2015GL064955
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Authors: Bonnell John, and Lanzerotti Louis J.
Title: Neutral Oxygen Effects at Low Earth Altitudes: A Critical Uncertainty for Spacecraft Operations and Space Weather Effects
Abstract: Space Weather sits at the intersection of natural phenomena interacting with modern technology—either in space or on Earth's surface. A key aspect of space weather is the interaction of Earth's extended neutral atmosphere with satellite surfaces [e.g., Samwel, 2014, and references therein]. Because neutral oxygen causes spacecraft surface erosion and oxidation, detailed knowledge of the atmosphere below 1000 km is essential for spacecraft design and operations.
Date: 07/2015 Publisher: Space Weather DOI: 10.1002/2015SW001229 Available at: http://doi.wiley.com/10.1002/2015SW001229
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Authors: Cho Junghee, Lee Dae-Young, Kim Jin-Hee, Shin Dae-Kyu, Kim Kyung-Chan, et al.
Title: New model fit functions of the plasmapause location determined using THEMIS observations during the ascending phase of Solar Cycle 24
Abstract: It is well known that the plasmapause is influenced by the solar wind and magnetospheric conditions. Empirical models of its location have been previously developed such as those by O'Brien and Moldwin (2003) and Larsen et al. (2006). In this study, we identified the locations of the plasmapause using the plasma density data obtained from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites. We used the data for the period (2008–2012) corresponding to the ascending phase of Solar Cycle 24. Our database includes data from over a year of unusually weak solar wind conditions, correspondingly covering the plasmapause locations in a wider L range than those in previous studies. It also contains many coronal hole stream intervals during which the plasmasp. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021030 Available at: http://doi.wiley.com/10.1002/2015JA021030
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Authors: Chen Lunjin, Maldonado Armando, Bortnik Jacob, Thorne Richard M, Li Jinxing, et al.
Title: Nonlinear Bounce Resonances between Magnetosonic Waves and Equatorially Mirroring Electrons
Abstract: Equatorially mirroring energetic electrons pose an interesting scientific problem, since they generally cannot resonate with any known plasma waves and hence cannot be scattered down to lower pitch angles. Observationally it is well known that the fluxof these equatorial particles does not simply continue to build up indefinitely, and so a mechanism must necessarily exist that transports these particles from a equatorial pitch angle of 90 degrees down to lower values. However this mechanism has not been uniquely identified yet. Here, we investigate the mechanism of bounce resonance with equatorial noise (or fast magnetosonic waves). A test particle simulation is used to examine the effects of monochromatic magnetosonic waves on the equatorially mirroring energetic electrons, with a special. . .
Date: 06/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021174 Available at: http://doi.wiley.com/10.1002/2015JA021174
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Authors: Tejero E. M., Crabtree C., Blackwell D. D., Amatucci W. E., Mithaiwala M., et al.
Title: Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma
Abstract: We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10−6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect t. . .
Date: 12/2015 Publisher: Scientific Reports Pages: 17852 DOI: 10.1038/srep17852 Available at: http://www.nature.com/articles/srep17852
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Authors: Agapitov O. V., Artemyev A. V., Mourenas D., Mozer F S, and Krasnoselskikh V.
Title: Nonlinear local parallel acceleration of electrons through Landau trapping by oblique whistler mode waves in the outer radiation belt
Abstract: Simultaneous observations of electron velocity distributions and chorus waves by the Van Allen Probe B are analyzed to identify long-lasting (more than 6 h) signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. Such Landau resonant interactions result in the trapping of ∼1–10 keV electrons and their acceleration up to 100–300 keV. This kind of process becomes important for oblique whistler mode waves having a significant electric field component along the background magnetic field. In the inhomogeneous geomagnetic field, such resonant interactions then lead to the formation of a plateau in the parallel (with respect to the geomagnetic field) velocity distribution due to trapping of electrons into the wave effective potential. We de. . .
Date: 12/2015 Publisher: Geophysical Research Letters Pages: 10,140 - 10,149 DOI: 10.1002/2015GL066887 Available at: http://doi.wiley.com/10.1002/2015GL066887http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL066887
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Authors: Fu Xiangrong, Guo Zehua, Dong Chuanfei, and Gary Peter
Title: Nonlinear subcyclotron resonance as a formationmechanism for gaps in banded chorus
Abstract: An interesting characteristic of magnetospheric chorus is the presence of a frequency gap at ω≃0.5Ωe, where Ωe is the electron cyclotron angular frequency. Recent chorus observations sometimes show additional gaps near 0.3Ωe and 0.6Ωe. Here we present a novel nonlinear mechanism for the formation of these gaps using Hamiltonian theory and test particle simulations in a homogeneous, magnetized, collisionless plasma. We find that an oblique whistler wave with frequency at a fraction of the electron cyclotron frequency can resonate with electrons, leading to effective energy exchange between the wave and particles.
Date: 05/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064182 Available at: http://doi.wiley.com/10.1002/2015GL064182
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Authors: Nikoukar Romina, Bust Gary, and Murr David
Title: A novel data assimilation technique for the plasmasphere
Abstract: We present a novel technique for imaging and data assimilation of the topside ionosphere and plasmasphere. The methodology is based upon the 3 dimensional variational technique (3DVAR), where an empirical background model is utilized. However, to prevent non-physical vertical variation in density estimates, we devise statistical methods to enforce a roughness penalty in the traditional 3DVAR optimization. The upward looking total electron content (TEC) observations from the Global Positioning System (GPS) receiver onboard Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) satellites are utilized in the assimilation algorithm. The estimation results show reasonable agreement with in-situ density measurements of Defense Meteorological Satellite Program satellites. . .
Date: 09/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021455 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015JA021455/abstract
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Authors: Blum L. W., Halford A., Millan R., Bonnell J. W., Goldstein J, et al.
Title: Observations of coincident EMIC wave activity and duskside energetic electron precipitation on 18-19 January 2013
Abstract: Electromagnetic ion cyclotron (EMIC) waves have been suggested to be a cause of radiation belt electron loss to the atmosphere. Here simultaneous, magnetically conjugate measurements are presented of EMIC wave activity, measured at geosynchronous orbit and on the ground, and energetic electron precipitation, seen by the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) campaign, on two consecutive days in January 2013. Multiple bursts of precipitation were observed on the duskside of the magnetosphere at the end of 18 January and again late on 19 January, concurrent with particle injections, substorm activity, and enhanced magnetospheric convection. The structure, timing, and spatial extent of the waves are compared to those of the precipitation during both days to det. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL065245 Available at: http://doi.wiley.com/10.1002/2015GL065245
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Authors: Zhima Zeren, Chen Lunjin, Fu Huishan, Cao Jinbin, Horne Richard, et al.
Title: Observations of discrete magnetosonic waves off the magnetic equator
Abstract: Fast mode magnetosonic waves are typically confined close to the magnetic equator and exhibit harmonic structures at multiples of the local, equatorial proton cyclotron frequency. We report observations of magnetosonic waves well off the equator at geomagnetic latitudes from −16.5°to −17.9° and L shell ~2.7–4.6. The observed waves exhibit discrete spectral structures with multiple frequency spacings. The predominant frequency spacings are ~6 and 9 Hz, neither of which is equal to the local proton cyclotron frequency. Backward ray tracing simulations show that the feature of multiple frequency spacings is caused by propagation from two spatially narrow equatorial source regions located at L ≈ 4.2 and 3.7. The equatorial proton cyclotron frequencies at those two locations mat. . .
Date: 12/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL066255 Available at: http://doi.wiley.com/10.1002/2015GL066255http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL066255
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Authors: Chi P. J., and Le G.
Title: Observations of magnetospheric high-m poloidal waves by ST-5 satellites in low Earth orbit during geomagnetically quiet times
Abstract: The poloidal waves with large azimuthal wavenumbers (m~100) in the magnetosphere are known to be generated by drift or drift bounce resonance with energetic ring current particles, and these waves may play a role in modulating the energetic particles in the inner magnetosphere. When examining the magnetic field data collected by the NASA ST-5 satellites in the low Earth orbit, Le et al. [2011] discovered many wave events with frequencies of 30–200 mHz (in the Pc 2–3 band), and they proposed that these waves should in fact be Doppler-shifted high-m poloidal waves in the magnetosphere with frequencies at only a few mHz (in the Pc 5 band). Using a new method that examines the differences in wave phase detected by the three ST-5 satellites, we confirm that the frequencies in the Earth fram. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021145 Available at: http://doi.wiley.com/10.1002/2015JA021145
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Authors: Saikin A. A., Zhang J.-C., Allen R.C., Smith C W, Kistler L. M., et al.
Title: The occurrence and wave properties of H + -, He + -, and O + -band EMIC waves observed by the Van Allen Probes
Abstract: We perform a statistical study of electromagnetic ion cyclotron (EMIC) waves detected by the Van Allen Probes mission to investigate the spatial distribution of their occurrence, wave power, ellipticity, and normal angle. The Van Allen Probes have been used which allow us to explore the inner magnetosphere (1.1 to 5.8 Re). Magnetic field measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science onboard the Van Allen Probes are used to identify EMIC wave events for the first 22 months of the mission operation (8 September 2012 – 30 June 2014). EMIC waves are examined in H+-, He+-, and O+-bands. Over 700 EMIC wave events have been identified over the three different wave bands (265 H+-band events, 438 He+-band events, and 68 O+-band events). EMIC wave events. . .
Date: 09/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021358 Available at: http://doi.wiley.com/10.1002/2015JA021358
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Authors: Wu S., Denton R. E., Liu K., and Hudson M K
Title: One- and two-dimensional hybrid simulations of whistler mode waves in a dipole field
Abstract: We simulate whistler mode waves using a hybrid code. There are four species in the simulations, hot electrons initialized with a bi-Maxwellian distribution with temperature in the direction perpendicular to background magnetic field greater than that in the parallel direction, warm isotropic electrons, cold inertialess fluid electrons, and protons as an immobile background. The density of the hot population is a small fraction of the total plasma density. Comparison between the dispersion relation of our model and other dispersion relations shows that our model is more accurate for lower frequency whistlers than for higher frequency whistlers. Simulations in 2-D Cartesian coordinates agree very well with those using a full dynamics code. In the 1-D simulations along the dipole magnetic fie. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 1908 - 1923 DOI: 10.1002/2014JA020736 Available at: http://doi.wiley.com/10.1002/2014JA020736
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Authors: Xiao Fuliang, Zhou Qinghua, He Yihua, Yang Chang, Liu Si, et al.
Title: Penetration of magnetosonic waves into the plasmasphere observed by the Van Allen Probes
Abstract: During the small storm on 14–15 April 2014, Van Allen Probe A measured a continuously distinct proton ring distribution and enhanced magnetosonic (MS) waves along its orbit outside the plasmapause. Inside the plasmasphere, strong MS waves were still present but the distinct proton ring distribution was falling steeply with distance. We adopt a sum of subtracted bi-Maxwellian components to model the observed proton ring distribution and simulate the wave trajectory and growth. MS waves at first propagate toward lower L shells outside the plasmasphere, with rapidly increasing path gains related to the continuous proton ring distribution. The waves then gradually cross the plasmapause into the deep plasmasphere, with almost unchanged path gains due to the falling proton ring distribution an. . .
Date: 09/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL065745 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015GL065745/full
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Authors: Kataoka Ryuho, Shiota Daikou, Kilpua Emilia, and Keika Kunihiro
Title: Pileup accident hypothesis of magnetic storm on 17 March 2015
Abstract: We propose a “pileup accident” hypothesis, based on the solar wind data analysis and magnetohydrodynamics modeling, to explain unexpectedly geoeffective solar wind structure which caused the largest magnetic storm so far during the solar cycle 24 on 17 March 2015: First, a fast coronal mass ejection with strong southward magnetic fields both in the sheath and in the ejecta was followed by a high-speed stream from a nearby coronal hole. This combination resulted in less adiabatic expansion than usual to keep the high speed, strong magnetic field, and high density within the coronal mass ejection. Second, preceding slow and high-density solar wind was piled up ahead of the coronal mass ejection just before the arrival at the Earth to further enhance its magnetic field and density. Finall. . .
Date: 07/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064816 Available at: http://doi.wiley.com/10.1002/2015GL064816
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Authors: Zhu Hui, Su Zhenpeng, Xiao Fuliang, Zheng Huinan, Wang Yuming, et al.
Title: Plasmatrough exohiss waves observed by Van Allen Probes: Evidence for leakage from plasmasphere and resonant scattering of radiation belt electrons
Abstract: Exohiss waves are whistler mode hiss observed in the plasmatrough region. We present a case study of exohiss waves and the corresponding background plasma distributions observed by the Van Allen Probes in the dayside low-latitude region. The analysis of wave Poynting fluxes, suprathermal electron fluxes and cold electron densities supports the scenario that exohiss leaks from the plasmasphere into the plasmatrough. Quasilinear calculations further reveal that exohiss can potentially cause the resonant scattering loss of radiation belt electrons ~Date: 02/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062964 Available at: http://doi.wiley.com/10.1002/2014GL062964
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Authors: Sarno-Smith Lois K., Liemohn Michael W., Katus Roxanne M., Skoug Ruth M., Larsen Brian A., et al.
Title: Postmidnight depletion of the high-energy tail of the quiet plasmasphere
Abstract: The Van Allen Probes Helium Oxygen Proton Electron (HOPE) instrument measures the high-energy tail of the thermal plasmasphere allowing study of topside ionosphere and inner magnetosphere coupling. We statistically analyze a 22 month period of HOPE data, looking at quiet times with a Kp index of less than 3. We investigate the high-energy range of the plasmasphere, which consists of ions at energies between 1 and 10 eV and contains approximately 5% of total plasmaspheric density. Both the fluxes and partial plasma densities over this energy range show H+ is depleted the most in the postmidnight sector (1–4 magnetic local time), followed by O+ and then He+. The relative depletion of each species across the postmidnight sector is not ordered by mass, which reveals ionospheric influence. We. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020682 Available at: http://doi.wiley.com/10.1002/2014JA020682
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Authors: Kim Jin-Hee, Lee Dae-Young, Cho Jung-Hee, Shin Dae-Kyu, Kim Kyung-Chan, et al.
Title: A prediction model for the global distribution of whistler chorus wave amplitude developed separately for two latitudinal zones
Abstract: Whistler mode chorus waves are considered to play a central role in accelerating and scattering electrons in the outer radiation belt. While in situ measurements are usually limited to the trajectories of a small number of satellites, rigorous theoretical modeling requires a global distribution of chorus wave characteristics. In the present work, by using a large database of chorus wave observations made on the Time History of Events and Macroscale Interactions during Substorms satellites for about 5 years, we develop prediction models for a global distribution of chorus amplitudes. The development is based on two main components: (a) the temporal dependence of average chorus amplitudes determined by correlating with the preceding solar wind and geomagnetic conditions as represented by t. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020900 Available at: http://doi.wiley.com/10.1002/2014JA020900
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Authors: Sakaguchi Kaori, Nagatsuma Tsutomu, Reeves Geoffrey, and Spence Harlan E.
Title: Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models
Abstract: The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary (GEO) and medium Earth orbit (MEO). To provide alerts of electron flux enhancements, sixteen prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omni-directional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES-15 spacecraft were used as the predictors. Model explanatory parameters were selected from solar wind parameters, the electron log-flux at GEO, and geo. . .
Date: 11/2015 Publisher: Space Weather Pages: n/a - n/a DOI: 10.1002/2015SW001254 Available at: http://doi.wiley.com/10.1002/2015SW001254http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015SW001254
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Authors: Kurita Satoshi, Kadokura Akira, Miyoshi Yoshizumi, Morioka Akira, Sato Yuka, et al.
Title: Relativistic electron precipitations in association with diffuse aurora: Conjugate observation of SAMPEX and the all sky TV camera at Syowa Station
Abstract: It has been believed that whistler mode waves can cause relativistic electron precipitations. It has been also pointed out that pitch angle scattering of ~keV electrons by whistler mode waves results in diffuse auroras. Thus, it is natural to expect relativistic electron precipitations associated with diffuse auroras. Based on a conjugate observation between the SAMPEX spacecraft and the all-sky TV camera at Syowa Station, we report, for the first time, a case in which relativistic electron precipitations are associated with diffuse aurora. The SAMPEX observation shows that the precipitations of >1 MeV electrons are well accompanied with those of >150 and >400 keV electrons. This indicates that electrons in the energy range from several keV to >1 MeV precipitate into the atmosphere s. . .
Date: 06/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064564 Available at: http://doi.wiley.com/10.1002/2015GL064564
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