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2014
Authors: Baker Daniel
Title: New Twists in Earth’s Radiation Belts
Abstract: In 1958, an early satellite, Explorer I, made the discovery that Earth is enshrouded in belts of extraordinarily high-energy, high-intensity radiation. Now called the Van Allen belts, after the researcher who led that satellite mission, these rings are known to wax and wane in intensity, for reasons that are still being investigated. Satellites now criss-cross these belts, so understanding what influences them has dire implications for communications and other technologies in our modern age. Solar storms and space weather can pump them up, making the radiation zones around Earth immensely more dangerous for days or even weeks on end. The author has been involved with instruments on the dual Radiation Belt Storm Probes satellites that were launched on August 30, 2012, into Earth orbit to st. . .
Date: 09/2014 Publisher: American Scientist Pages: 374 DOI: 10.1511/2014.110.374 Available at: http://www.americanscientist.org/issues/feature/2014/5/new-twists-in-earths-radiation-belts
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Authors: Malaspina D. M., Andersson L., Ergun R. E., Wygant J R, Bonnell J W, et al.
Title: Nonlinear Electric Field Structures in the Inner Magnetosphere
Abstract: Van Allen Probes observations are presented which demonstrate the presence of nonlinear electric field structures in the inner terrestrial magnetosphere (< 6 RE). A range of structures are observed, including phase space holes and double layers.These structures are observed over several Earth radii in radial distance and over a wide range of magnetic local times. They are observed in the dusk, midnight, and dawn sectors, with the highest concentration pre-midnight. Some nonlinear electric field structures are observed to coincide with dipolarizations of the magnetic field and increases in electron energy flux for energies between 1 keV and 30 keV. Nonlinear electric field structures possess isolated impulsive electric fields, often with a significant component parallel to the ambient m. . .
Date: 08/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL061109 Available at: http://doi.wiley.com/10.1002/2014GL061109
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Authors: Su Zhenpeng, Xiao Fuliang, Zheng Huinan, He Zhaoguo, Zhu Hui, et al.
Title: Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes
Abstract: Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21–24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10−4nT2/Hz) occurred in the region L>5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors . . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 229 - 235 DOI: 10.1002/2013GL058912 Available at: http://doi.wiley.com/10.1002/2013GL058912
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Authors: Schiller Quintin, Li Xinlin, Blum Lauren, Tu Weichao, Turner Drew L, et al.
Title: A nonstorm time enhancement of relativistic electrons in the outer radiation belt
Abstract: Despite the lack of a geomagnetic storm (based on the Dst index), relativistic electron fluxes were enhanced over 2.5 orders of magnitude in the outer radiation belt in 13 h on 13–14 January 2013. The unusual enhancement was observed by Magnetic Electron Ion Spectrometer (MagEIS), onboard the Van Allen Probes; Relativistic Electron and Proton Telescope Integrated Little Experiment, onboard the Colorado Student Space Weather Experiment; and Solid State Telescope, onboard Time History of Events and Macroscale Interactions during Substorms (THEMIS). Analyses of MagEIS phase space density (PSD) profiles show a positive outward radial gradient from 4 < L < 5.5. However, THEMIS observations show a peak in PSD outside of the Van Allen Probes' apogee, which suggest a very interesting s. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 7 - 12 DOI: 10.1002/2013GL058485 Available at: http://doi.wiley.com/10.1002/2013GL058485
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Authors: Chaston Christopher C., Bonnell J W, Wygant John R., Mozer Forrest, Bale Stuart D., et al.
Title: Observations of kinetic scale field line resonances
Abstract: We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfvénic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field-line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 209 - 215 DOI: 10.1002/2013GL058507 Available at: http://doi.wiley.com/10.1002/2013GL058507
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Authors: Selesnick R. S., Baker D N, Jaynes A. N., Li X, Kanekal S G, et al.
Title: Observations of the inner radiation belt: CRAND and trapped solar protons
Abstract: Measurements of inner radiation belt protons have been made by the Van Allen Probes Relativistic Electron-Proton Telescopes as a function of kinetic energy (24 to 76 MeV), equatorial pitch angle, and magnetic L shell, during late-2013 and early-2014. A probabilistic data analysis method reduces background from contamination by higher energy protons. Resulting proton intensities are compared to predictions of a theoretical radiation belt model. Then trapped protons originating both from cosmic ray albedo neutron decay (CRAND) and from trapping of solar protons are evident in the measured distributions. An observed double-peaked distribution in L is attributed, based on the model comparison, to a gap in the occurrence of solar proton events during the 2007 to 2011 solar minimum. Equatorial. . .
Date: 08/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020188 Available at: http://doi.wiley.com/10.1002/2014JA020188
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Authors: Zhao H., Li X, Blake J B, Fennell J. F., Claudepierre S G, et al.
Title: Peculiar pitch angle distribution of relativistic electrons in the inner radiation belt and slot region
Abstract: The relativistic electrons in the inner radiation belt have received little attention in the past due to sparse measurements and unforgiving contamination from the inner belt protons. The high-quality measurements of the Magnetic Electron Ion Spectrometer instrument onboard Van Allen Probes provide a great opportunity to investigate the dynamics of relativistic electrons in the low L region. In this letter, we report the newly unveiled pitch angle distribution (PAD) of the energetic electrons with minima at 90° near the magnetic equator in the inner belt and slot region. Such a PAD is persistently present throughout the inner belt and appears in the slot region during storms. One hypothesis for 90° minimum PADs is that off 90° electrons are preferentially heated by chorus waves just out. . .
Date: 04/2014 Publisher: Geophysical Research Letters Pages: 2250 - 2257 DOI: 10.1002/2014GL059725 Available at: http://doi.wiley.com/10.1002/2014GL059725
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Authors: Kletzing Craig A.
Title: Progress on understanding chorus emissions from data of the electric and magnetic field instrument suite and integrated science (EMFISIS) on the Van Allen Probes
Abstract: The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A key wave-particle interaction important to both acceleration and loss in the radiation belts is the of whistler-mode chorus interacting with energetic electrons. To measure this important radiation belt interaction, the two-satellite Van Allen Probes mission utilizes one of the most complete sets of measurements ever made in the inner magnetosphere. As part of the mission, the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnet. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929872 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929872
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Authors: Foster J. C., Erickson P. J., Baker D N, Claudepierre S G, Kletzing C A, et al.
Title: Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations
Abstract: On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. The 100 keV electrons and intense VLF waves provide a seed population and energy source for subsequent radiation belt enhancements. Highly relativistic (>2 MeV) electron fluxes increased immediately at L* ~ 4.5. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 20 - 25 DOI: 10.1002/2013GL058438 Available at: http://doi.wiley.com/10.1002/2013GL058438
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Authors: Foster John C, and Erickson Philip J.
Title: Prompt energization of relativistic and highly relativistic electrons during a substorm interval
Abstract: On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ∼6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons [1]. A 50% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes and a 100 times increase in VLF wave intensity. Chorus is excited following the injection of low-energy (1–30 keV) plasma sheet electrons into the inner magnetosphere [2]. During the 17 March substorm injection, cold plasma that had circulated into the nightside. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929876 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929876
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Authors: Li W, Ni B, Thorne R M, Bortnik J, Nishimura Y., et al.
Title: Quantifying hiss-driven energetic electron precipitation: A detailed conjunction event analysis
Abstract: We analyze a conjunction event between the Van Allen Probes and the low-altitude Polar Orbiting Environmental Satellite (POES) to quantify hiss-driven energetic electron precipitation. A physics-based technique based on quasi-linear diffusion theory is used to estimate the ratio of precipitated and trapped electron fluxes (R), which could be measured by the two-directional POES particle detectors, using wave and plasma parameters observed by the Van Allen Probes. The remarkable agreement between modeling and observations suggests that this technique is applicable for quantifying hiss-driven electron scattering near the bounce loss cone. More importantly, R in the 100–300 keV energy channel measured by multiple POES satellites over a broad L magnetic local time region can potentially pr. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 1085 - 1092 DOI: 10.1002/2013GL059132 Available at: http://doi.wiley.com/10.1002/2013GL059132
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Authors: Boyd A. J., Spence H E, Claudepierre S G, Fennell J. F., Blake J B, et al.
Title: Quantifying the radiation belt seed population in the 17 March 2013 electron acceleration event
Abstract: We present phase space density (PSD) observations using data from the Magnetic Electron Ion Spectrometer instrument on the Van Allen Probes for the 17 March 2013 electron acceleration event. We confirm previous results and quantify how PSD gradients depend on the first adiabatic invariant. We find a systematic difference between the lower-energy electrons (1 MeV with a source region within the radiation belts. Our observations show that the source process begins with enhancements to the 10s–100s keV energy seed population, followed by enhancements to the >1 MeV population and eventually leading to enhancements in the multi-MeV electron population. These observations provide the clearest evidence to date . . .
Date: 04/2014 Publisher: Geophysical Research Letters Pages: 2275 - 2281 DOI: 10.1002/2014GL059626 Available at: http://doi.wiley.com/10.1002/2014GL059626
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Authors: Su Zhenpeng, Zhu Hui, Xiao Fuliang, Zheng Huinan, Wang Yuming, et al.
Title: Quantifying the relative contributions of substorm injections and chorus waves to the rapid outward extension of electron radiation belt
Abstract: We study the rapid outward extension of the electron radiation belt on a timescale of several hours during three events observed by RBSP and THEMIS satellites, and particularly quantify the contributions of substorm injections and chorus waves to the electron flux enhancement near the outer boundary of radiation belt. A comprehensive analysis including both observations and simulations is performed for the first event on 26 May 2013. The outer boundary of electron radiation belt moved from L = 5.5 to L > 6.07 over about 6 hours, with up to four orders of magnitude enhancement in the 30 keV-5 MeV electron fluxes at L = 6. The observations show that the substorm injection can cause 100% and 20% of the total subrelativistic (~0.1 MeV) and relativistic (2-5 MeV) electron . . .
Date: 12/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020709 Available at: http://doi.wiley.com/10.1002/2014JA020709
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Authors: Gerrard Andrew, Lanzerotti Louis, Gkioulidou Matina, Mitchell Donald, Manweiler Jerry, et al.
Title: Quiet time observations of He ions in the inner magnetosphere as observed from the RBSPICE instrument aboard the Van Allen Probes mission
Abstract: He ions contribute to Earth's ring current energy and species population density and are important in understanding ion transport and charge exchange processes in the inner magnetosphere. He ion flux measurements made by the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument are presented in this paper. Particular focus is centered on geomagnetically quiet intervals in late 2012 and 2013 that show the flux, L-shell, and energy (65 keV to 518 keV) morphology of ring current He ions between geomagnetic storm injection events. The overall He ion abundance during the first nine months of RBSPICE observations, the appearance of a persistent high energy, low L-shell He ion population, and the temporal evolution of this population all provide new insights. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 1100 - 1105 DOI: 10.1002/2013GL059175 Available at: http://doi.wiley.com/10.1002/2013GL059175
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Authors: Holmes-Siedle A G, Goldsten J O, Maurer R H, and Peplowski P N
Title: RadFET Dosimeters in the Belt: the Van Allen Probes on Day 365
Abstract: Van Allen Probes A and B, launched more than a year ago (in August 2012), carried 16 p-channel metal-oxide-semiconductor Radiation-sensitive Field Effect Transistors (RadFET)s into an orbit designed by NASA to probe the heart of the trapped-radiation belts. Nearly 350 days of in situ measurements from the Engineering Radiation Monitor (ERM) (1) demonstrated strong variations of dose rates with time, (2) revealed a critical correlation between the ERM RadFET dosimeters and the ERM Faraday cup data on charged particles, and (3) permitted the mapping of the belts by measuring variation with orbit altitude. This paper provides an update on early results given in a NSREC2012 paper along with details and discussion of the RadFET dosimetry data analyzed .
Date: 04/2014 Publisher: IEEE Transactions on Nuclear Science Pages: 948 - 954 DOI: 10.1109/TNS.2014.2307012 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6786389
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Authors: Li Zhao, Hudson Mary, and Chen Yue
Title: Radial diffusion comparing a THEMIS statistical model with geosynchronous measurements as input
Abstract: The outer boundary energetic electron flux is used as a driver in radial diffusion calculations, and its precise determination is critical to the solution. A new model was proposed recently based on Time History of Events and Macroscale Interactions during Substorms (THEMIS) measurements to express the boundary flux as three fit functions of solar wind parameters in a response window that depend on energy and which solar wind parameter is used: speed, density, or both. The Dartmouth radial diffusion model has been run using Los Alamos National Laboratory (LANL) geosynchronous satellite measurements as the constraint for a one-month interval in July to August 2004, and the calculated phase space density (PSD) is compared with GPS measurements, at magnetic equatorial plane crossings, as a te. . .
Date: 03/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 1863 - 1873 DOI: 10.1002/jgra.v119.310.1002/2013JA019320 Available at: http://doi.wiley.com/10.1002/jgra.v119.3http://doi.wiley.com/10.1002/2013JA019320
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Authors: Li W, Thorne R M, Ma Q, Ni B, Bortnik J, et al.
Title: Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm
Abstract: Local acceleration driven by whistler-mode chorus waves is fundamentally important for accelerating seed electron populations to highly relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus-driven electron acceleration during the 17 March 2013 storm, when the Van Allen Probes observed very rapid electron acceleration up to several MeV within ~12 hours. A clear radial peak in electron phase space density (PSD) observed near L* ~4 indicates that an internal local acceleration process was operating. We construct the global distribution of chorus wave intensity from the low-altitude electron measurements made by multiple Polar Orbiting Environmental Satellites (POES) satellites over a broad region, which is ultimately used to simulate the radiati. . .
Date: 06/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 4681 - 4693 DOI: 10.1002/jgra.v119.610.1002/2014JA019945 Available at: http://doi.wiley.com/10.1002/jgra.v119.6http://doi.wiley.com/10.1002/2014JA019945
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Authors: Thorne R M, Li W, Ma Q, Ni B, and Bortnik J
Title: Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm
Abstract: Local acceleration driven by whistler-mode chorus waves is suggested to be fundamentally important for accelerating seed electron population to ultra-relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus-driven electron acceleration during the 17 March 2013 storm, when Van Allen Probes observed very rapid electron acceleration up to multi MeV within ∼15 hours. A clear peak in electron phase space density observed at L∗ ∼ 4 indicates that the internal local acceleration process was operating. We construct the global distribution of chorus wave intensity from the low-altitude electron measurements by multiple POES satellites over a broad L-MLT region, which is used to simulate the radiation belt electron dynamics driven by chorus waves. Our. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929882 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929882
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Authors: McCarthy Michael P., Millan Robyn M., Sample John G., and Smith David M.
Title: Radiation belt losses observed from multiple stratospheric balloons over Antarctica
Abstract: Relativistic electrons, trapped by Earth's magnetic field, have received increasing attention since increasing numbers of commercial and research spacecraft traverse regions of high radiation flux. The Van Allen probes were launched into Earth's radiation belts in September 2012, making comprehensive measurements of charged particle fluxes and electromagnetic fields, with the objective of a better understanding of the processes that modulate radiation belt fluxes. Because losses of radiation belt electrons to Earth's atmosphere are very difficult to measure from high altitude spacecraft, a balloon-based program, consisting of campaigns in January 2013 and 2014, was funded to measure losses in conjunction with the Van Allen probes mission. We present results from both balloon campaigns, whi. . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929960 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929960
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Authors: Kletzing C. A.
Title: Recent results from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Van Allen Probes
Abstract: The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field and particle interactions are involved in this physics from large-scale ring current ion and magnetic field dynamics to microscopic kinetic interactions of whistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASA implemented the two-satellite Van Allen Probes mission. As part of the mission, the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set of instruments consisting of a tri-axial fluxgate magnetometer (MAG) and a Waves instrument which includes a tri-axial search coil magnetometer. . .
Date: 01/2014 Publisher: IEEE DOI: 10.1109/USNC-URSI-NRSM.2014.6928090 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6928090
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Authors: Chen Y., Friedel R. H. W., Henderson M. G., Claudepierre S. G., Morley S., et al.
Title: REPAD: An Empirical Model of Pitch-angle Distributions for Energetic Electrons in the Earth’s Outer Radiation Belt
Abstract: We have recently conducted a statistical survey on pitch angle distributions of energetic electrons trapped in the Earth's outer radiation belt, and a new empirical model was developed based upon survey results. This model—relativistic electron pitch angle distribution (REPAD)—aims to present statistical pictures of electron equatorial pitch angle distributions, instead of the absolute flux levels, as a function of energy, L shell, magnetic local time, and magnetic activity. To quantify and facilitate this statistical survey, we use Legendre polynomials to fit long-term in situ directional fluxes observed near the magnetic equator from three missions: CRRES, Polar, and LANL-97A. As the first of this kind of model, REPAD covers the whole outer belt region, providing not only the mean an. . .
Date: 03/2014 Publisher: Journal of Geophysical Research Pages: 1693-1708 DOI: 10.1002/2013JA019431 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2013JA019431/full
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Authors: Ni Binbin, Li Wen, Thorne Richard M, Bortnik Jacob, Ma Qianli, et al.
Title: Resonant scattering of energetic electrons by unusual low-frequency hiss
Abstract: We quantify the resonant scattering effects of the unusual low-frequency dawnside plasmaspheric hiss observed on 30 September 2012 by the Van Allen Probes. In contrast to normal (~100–2000 Hz) hiss emissions, this unusual hiss event contained most of its wave power at ~20–200 Hz. Compared to the scattering by normal hiss, the unusual hiss scattering speeds up the loss of ~50–200 keV electrons and produces more pronounced pancake distributions of ~50–100 keV electrons. It is demonstrated that such unusual low-frequency hiss, even with a duration of a couple of hours, plays a particularly important role in the decay and loss process of energetic electrons, resulting in shorter electron lifetimes for ~50–400 keV electrons than normal hiss, and should be carefully incorpora. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1854 - 1861 DOI: 10.1002/2014GL059389 Available at: http://doi.wiley.com/10.1002/2014GL059389
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Authors: Yu Yiqun, Jordanova Vania, Welling Dan, Larsen Brian, Claudepierre Seth G., et al.
Title: The role of ring current particle injections: Global simulations and Van Allen Probes observations during 17 March 2013 storm
Abstract: We simulate substorm injections observed by the Van Allen Probes during the 17 March 2013 storm using a self-consistent coupling between the ring current model RAM-SCB and the global MHD model BATS-R-US. This is a significant advancement compared to previous studies that used artificially imposed electromagnetic field pulses to mimic substorm dipolarization and associated inductive electric field. Several substorm dipolarizations and injections are reproduced in the MHD model, in agreement with the timing of shape changes in the AE/AL index. The associated inductive electric field transports plasma sheet plasma to geostationary altitudes, providing the boundary plasma source to the ring current model. It is found that impulsive plasma sheet injections, together with a large-scale convectio. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 1126 - 1132 DOI: 10.1002/2014GL059322 Available at: http://doi.wiley.com/10.1002/2014GL059322
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Authors: Gkioulidou Matina, Ukhorskiy A., Mitchell D G, Sotirelis T., Mauk B., et al.
Title: The role of small-scale ion injections in the buildup of Earth's ring current pressure: Van Allen Probes observations of the March 17 th , 2013 storm
Abstract: Energetic particle transport into the inner magnetosphere during geomagnetic storms is responsible for significant plasma pressure enhancement, which is the driver of large-scale currents that control the global electrodynamics within the magnetosphere-ionosphere system. Therefore, understanding the transport of plasma from the tail deep into the near-Earth magnetosphere, as well as the energization processes associated with this transport, is essential for a comprehensive knowledge of the near-Earth space environment. During the main phase of a geomagnetic storm on March 17th 2013 (minimum Dst ~ −137 nT), the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on the Van Allen Probes observed frequent, small-scale proton injections deep into the inner nightsi. . .
Date: 09/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020096 Available at: http://doi.wiley.com/10.1002/2014JA020096
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Authors: Ukhorskiy A Y, Sitnov M I, Mitchell D G, Takahashi K, Lanzerotti L J, et al.
Title: Rotationally driven ‘zebra stripes’ in Earth’s inner radiation belt
Abstract: Structured features on top of nominally smooth distributions of radiation-belt particles at Earth have been previously associated with particle acceleration and transport mechanisms powered exclusively by enhanced solar-wind activity1, 2, 3, 4. Although planetary rotation is considered to be important for particle acceleration at Jupiter and Saturn5, 6, 7, 8, 9, the electric field produced in the inner magnetosphere by Earth’s rotation can change the velocity of trapped particles by only about 1–2 kilometres per second, so rotation has been thought inconsequential for radiation-belt electrons with velocities of about 100,000 kilometres per second. Here we report that the distributions of energetic electrons across the entire spatial extent of Earth’s inner radiation belt are organize. . .
Date: 01/2014 Publisher: Nature Pages: 338 - 340 DOI: 10.1038/nature13046 Available at: http://www.nature.com/doifinder/10.1038/nature13046
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Authors: Finnigan Jeremiah
Title: A scripting framework for automated flight SW testing: Van Allen Probes lessons learned
Abstract: This paper summarizes the lessons learned from implementing and utilizing an automated flight software test framework for the Van Allen Probes mission. This includes a recommended list of features/characteristics that a test framework should support. This paper also presents two test scripting design patterns that are useful for constructing an automated regression test suite. These design patterns are intended for non-object-oriented scripting environments - which is typical of space mission ground systems. A process flow is described for developing and utilizing an automated test scripting framework for future missions based upon the design patterns presented herein.
Date: 03/2014 Publisher: IEEE DOI: 10.1109/AERO.2014.6836164 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6836164
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Authors: Hudson M K, Baker D N, Goldstein J, Kress B T, Paral J., et al.
Title: Simulated magnetopause losses and Van Allen Probe flux dropouts
Abstract: Three radiation belt flux dropout events seen by the Relativistic Electron Proton Telescope soon after launch of the Van Allen Probes in 2012 (Baker et al., 2013a) have been simulated using the Lyon-Fedder-Mobarry MHD code coupled to the Rice Convection Model, driven by measured upstream solar wind parameters. MHD results show inward motion of the magnetopause for each event, along with enhanced ULF wave power affecting radial transport. Test particle simulations of electron response on 8 October, prior to the strong flux enhancement on 9 October, provide evidence for loss due to magnetopause shadowing, both in energy and pitch angle dependence. Severe plasmapause erosion occurred during ~ 14 h of strongly southward interplanetary magnetic field Bz beginning 8 October coincident with. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 1113 - 1118 DOI: 10.1002/2014GL059222 Available at: http://doi.wiley.com/10.1002/2014GL059222
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Authors: Goldstein J, De Pascuale S., Kletzing C., Kurth W., Genestreti K. J., et al.
Title: Simulation of Van Allen Probes Plasmapause Encounters
Abstract: We use an E × B-driven plasmapause test particle (PTP) simulation to provide global contextual information for in situ measurements by the Van Allen Probes (RBSP) during 15–20 January 2013. During 120 h of simulation time beginning on 15 January, geomagnetic activity produced three plumes. The third and largest simulated plume formed during enhanced convection on 17 January, and survived as a rotating, wrapped, residual plume for tens of hours. To validate the simulation, we compare its output with RBSP data. Virtual RBSP satellites recorded 28 virtual plasmapause encounters during 15–19 January. For 26 of 28 (92%) virtual crossings, there were corresponding actual RBSP encounters with plasmapause density gradients. The mean difference in encounter time between model and data is. . .
Date: 09/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020252 Available at: http://doi.wiley.com/10.1002/2014JA020252
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Authors: Jordanova V K, Yu Y., Niehof J T, Skoug R M, Reeves G D, et al.
Title: Simulations of inner magnetosphere dynamics with an expanded RAM-SCB model and comparisons with Van Allen Probes observations
Abstract: Simulations from our newly expanded ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB), now valid out to 9 RE, are compared for the first time with Van Allen Probes observations. The expanded model reproduces the storm time ring current buildup due to the increased convection and inflow of plasma from the magnetotail. It matches Magnetic Electron Ion Spectrometer (MagEIS) observations of the trapped high-energy (>50 keV) ion flux; however, it underestimates the low-energy (<10 keV) Helium, Oxygen, Proton, and Electron (HOPE) observations. The dispersed injections of ring current ions observed with the Energetic particle, Composition, and Thermal plasma (ECT) suite at high (>20 keV) energy are better reproduced using a high-resolution convection model. . . .
Date: 04/2014 Publisher: Geophysical Research Letters Pages: 2687 - 2694 DOI: 10.1002/2014GL059533 Available at: http://doi.wiley.com/10.1002/2014GL059533
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Authors: Reid Mark, and Ottman Geffrey
Title: Software controlled memory scrubbing for the Van Allen Probes Solid State Recorder (SSR) memory
Abstract: The Van Allen Probes mission which was designed and built by the Johns Hopkins University, Applied Physics Laboratory (APL) is also being operated by the APL mission operations team in Laurel, Maryland. The two Van Allen Probes spacecraft have been successfully collecting data on orbit since they were launched on August 30, 2012. These twin probes are providing unprecedented insight into the physical dynamics of the Earth's radiation belts and are giving scientists the data they need to make predictions of changes in this critical region of space, by sampling the harsh radiation belt environment where major space weather activity occurs and many spacecraft operate.[1] Shortly after launch, radiation induced anomalies were reported on both spacecraft and investigated by the hardware and sof. . .
Date: 03/2014 Publisher: IEEE DOI: 10.1109/AERO.2014.6836406 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6836406
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Authors: Turner Drew L
Title: Space science: Near-Earth space shows its stripes
Abstract: Using some of the first scientific satellites put into orbit during the late 1950s, teams led by physicists James Van Allen in the United States and Sergei Vernov in the Soviet Union independently reported1, 2 on defined regions of radiation in near-Earth space. These regions came to be known as Earth's radiation belts, and they represent the first major scientific discovery of the space age. However, despite decades of study, many questions in radiation-belt physics remain unanswered, mostly concerning the nature of the inner and outer belts, which are populated by electrons moving at near the speed of light. As society becomes ever more dependent on satellite-based technology, it is increasingly important to understand the variability in the radiation belts, because the highest-energy . . .
Date: 03/2014 Publisher: Nature Pages: 308 - 309 DOI: 10.1038/507308a Available at: http://www.nature.com/doifinder/10.1038/507308a
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Authors: Mann I. R., Usanova M. E., Murphy K., Robertson M. T., Milling D. K., et al.
Title: Spatial localization and ducting of EMIC waves: Van Allen Probes and ground-based observations
Abstract: On 11 October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 h) of continuous electromagnetic ion cyclotron (EMIC) waves was observed by Canadian Array for Real-time Investigations of Magnetic Activity and Solar-Terrestrial Environment Program induction coil magnetometers in North America. At around 14:15 UT, both Van Allen Probes B and A (65° magnetic longitude apart) in conjunction with the ground array observed very narrow (ΔL ~ 0.1–0.4) left-hand polarized EMIC emission confined to regions of mass density gradients at the outer edge of the plasmasphere at L ~ 4. EMIC waves were seen with complex polarization patterns on the ground, in good agreement with model results from Woodroffe and Lysak (2012) and consistent with Earth's . . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 785 - 792 DOI: 10.1002/2013GL058581 Available at: http://doi.wiley.com/10.1002/2013GL058581
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Authors: Berman Simmie, Cheng Weilun, Borowski Heather, and Persons David
Title: Spin stabilization design and testing of the Van Allen Probes
Abstract: This paper describes the design decisions taken and the mass properties tracking and testing flow chosen for the Van Allen Probes spacecraft and their deployable systems to achieve the coning angle requirements. Topics include a list of major requirements, a brief description of the error budget, a description of the tracking process of the spacecraft mass properties prior to test, a description of the spin balance and mass properties testing of the spacecraft core and deployable systems, and a presentation of the final mass properties and coning angle calculations of the fully deployed observatories. Launched August 30, 2012, the observed on-orbit, fully deployed configuration coning angles met the requirements, validating the spin balance and mass properties tracking, testing, and calcul. . .
Date: 03/2014 Publisher: IEEE DOI: 10.1109/AERO.2014.6836234 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6836234
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Authors: Santolik O, Hospodarsky G B, Kurth W S, Averkamp T. F., Kletzing C A, et al.
Title: Statistical properties of wave vector directions of whistler-mode waves in the radiation belts based on measurements of the Van Allen probes and Cluster missions
Abstract: Wave-particle interactions in the Earth's Van Allen radiation belts are known to be an efficient process of the exchange of energy between different particle populations, including the energetic radiation belt particles. The whistler mode waves, especially chorus, can control the radiation belt dynamics via linear or nonlinear interactions with both the energetic radiation belt electrons and lower energy electron populations. Wave vector directions are a very important parameter of these wave-particle interactions. We use measurements of whistlermode waves by the WAVES instrument from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard the Van Allen Probes spacecraft covering the equatorial region of the Earth's magnetosphere in all MLT sectors, and a . . .
Date: 08/2014 Publisher: IEEE DOI: 10.1109/URSIGASS.2014.6929880 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6929880
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Authors: Foster J. C., Erickson P. J., Coster A. J., Thaller S., Tao J., et al.
Title: Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere
Abstract: Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ −130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP F-18. Plasma erosion occurs at both high and low altitudes where the subauroral polarization stream flow overlaps the outer plasmasphere. At ~20 UT, RBSP-A observed ~1.2E12 m−2 s−1 erosion flux, while DMSP F-18 observed ~2E13 m−2 s−1 sunward flux. We. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 762 - 768 DOI: 10.1002/2013GL059124 Available at: http://doi.wiley.com/10.1002/2013GL059124
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Authors: Makela Jonathan J., Harding Brian J., Meriwether John W., Mesquita Rafael, Sanders Samuel, et al.
Title: Storm time response of the mid-latitude thermosphere: Observations from a network of Fabry-Perot interferometers
Abstract: Observations of thermospheric neutral winds and temperatures obtained during a geomagnetic storm on 2 October 2013 from a network of six Fabry-Perot interferometers (FPIs) deployed in the midwest United States are presented. Coincident with the commencement of the storm, the apparent horizontal wind is observed to surge westward and southward (towards the equator). Simultaneous to this surge in the apparent horizontal winds, an apparent downward wind of approximately 100 m/s lasting for 6 hours is observed. The apparent neutral temperature is observed to increase by approximately 400 K over all of the sites. Observations from an all-sky imaging system operated at the Millstone Hill observatory indicate the presence of a stable auroral red (SAR) arc and diffuse red aurora during this . . .
Date: 08/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA019832 Available at: http://doi.wiley.com/10.1002/2014JA019832
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Authors: Artemyev A. V., Agapitov O. V., Mozer F, and Krasnoselskikh V.
Title: Thermal electron acceleration by localized bursts of electric field in the radiation belts
Abstract: In this paper we investigate the resonant interaction of thermal ~10−100 eV electrons with a burst of electrostatic field that results in electron acceleration to kilovolt energies. This single burst contains a large parallel electric field of one sign and a much smaller, longer lasting parallel field of the opposite sign. The Van Allen Probe spacecraft often observes clusters of spatially localized bursts in the Earth's outer radiation belts. These structures propagate mostly away from thegeomagnetic equator and share properties of soliton-like nonlinear electron-acoustic waves: a velocity of propagation is about the thermal velocity of cold electrons (~3000−10000 km/s), and a spatial scale of electric field localization alongthe field lines is about the Debye radius of hot electrons . . .
Date: 08/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL061248 Available at: http://doi.wiley.com/10.1002/2014GL061248
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Authors: Ma Q, Li W, Chen L, Thorne R M, Kletzing C A, et al.
Title: The trapping of equatorial magnetosonic waves in the Earth's outer plasmasphere
Abstract: We investigate the excitation and propagation of equatorial magnetosonic waves observed by the Van Allen Probes and describe evidence for a trapping mechanism for magnetosonic waves in the Earth's plasmasphere. Intense equatorial magnetosonic waves were observed inside the plasmasphere in association with a pronounced proton ring distribution, which provides free energy for wave excitation. Instability analysis along the inbound orbit demonstrates that broadband magnetosonic waves can be excited over a localized spatial region near the plasmapause. The waves can subsequently propagate into the inner plasmasphere and remain trapped over a limited radial extent, consistent with the predictions of near-perpendicular propagation. By performing a similar analysis on another observed magnetosoni. . .
Date: 09/2014 Publisher: Geophysical Research Letters Pages: 6307 - 6313 DOI: 10.1002/2014GL061414 Available at: http://doi.wiley.com/10.1002/2014GL061414
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Authors: Betz Eric O.
Title: Trapping waves in Earth's plasmasphere
Abstract: Earth's magnetic field traps donut-shaped bands of radiation in a belt around the planet that react to solar eruptions by growing and shrinking. The Van Allen belts consist of two rings filled with particles from the solar wind and cosmic rays. Within the outer ring of the Van Allen belt sits the plasmasphere, which is the innermost part of the planet's magnetic field and home to low-energy charged particles.
Date: 12/2014 Publisher: Eos, Transactions American Geophysical Union Pages: 472 - 472 DOI: 10.1002/2014EO490016 Available at: http://doi.wiley.com/10.1002/eost.v95.49http://doi.wiley.com/10.1002/2014EO490016
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Authors: Boardsen S. A., Hospodarsky G B, Kletzing C A, Pfaff R. F., Kurth W S, et al.
Title: Van Allen Probe Observations of Periodic Rising Frequencies of the Fast Magnetosonic Mode
Abstract: Near simultaneous periodic dispersive features of fast magnetosonic mode emissions are observed by both Van Allen Probes spacecraft while separated in magnetic local time by ~5 hours: Probe A at 15 and Probe B at 9–11 hours. Both spacecraft see similar frequency features, characterized by a periodic repetition at ~180 s. Each repetition is characterized by a rising frequency. Since no modulation is observed in the proton shell distribution, the plasma density, or in the background magnetic field at either spacecraft we conclude that these waves are not generated near the spacecraft but external to both spacecraft locations. Probe A while outside the plasmapause sees the start of each repetition ~40 s before probe B while deep inside the plasmasphere. We can qualitatively reproduce . . .
Date: 12/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062020 Available at: http://doi.wiley.com/10.1002/2014GL062020
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Authors: Fennell J. F., Roeder J. L., Kurth W S, Henderson M G, Larsen B A, et al.
Title: Van Allen Probes observations of direct wave-particle interactions
Abstract: Quasiperiodic increases, or “bursts,” of 17–26 keV electron fluxes in conjunction with chorus wave bursts were observed following a plasma injection on 13 January 2013. The pitch angle distributions changed during the burst events, evolving from sinN(α) to distributions that formed maxima at α = 75–80°, while fluxes at 90° and <60° remained nearly unchanged. The observations occurred outside of the plasmasphere in the postmidnight region and were observed by both Van Allen Probes. Density, cyclotron frequency, and pitch angle of the peak flux were used to estimate resonant electron energy. The result of ~15–35 keV is consistent with the energies of the electrons showing the flux enhancements and corresponds to electrons in and above the steep flux gradient that signa. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1869 - 1875 DOI: 10.1002/2013GL059165 Available at: http://doi.wiley.com/10.1002/2013GL059165
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Authors: Fu Xiangrong, Cowee Misa M., Friedel Reinhard H., Funsten Herbert O, Gary Peter, et al.
Title: Whistler Anisotropy Instabilities as the Source of Banded Chorus: Van Allen Probes Observations and Particle-in-Cell Simulations
Abstract: Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr < Ωe, where Ωe is the electron cyclotron frequency, and a characteristic spectral gap at ωr ≃ Ωe/2. This paper uses spacecraft observations and two-dimensional particle-in-cell (PIC) simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from HOPE instrument measurements on the Van Allen Probes A satellite during a banded chorus event on 1 November 2012. The observations are consistent with a three-component electron mod. . .
Date: 10/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020364 Available at: http://doi.wiley.com/10.1002/2014JA020364
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2015
Authors: de Soria-Santacruz M., Li W, Thorne R M, Ma Q, Bortnik J, et al.
Title: Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations
Abstract: Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth's radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution, or the limited in-situ satellite wave measurements from satellites. This paper evaluates the performance and limitations of a novel technique capable of inferring wave amplitudes from low-altitude electron flux observations from the POES spacecraft, which provide extensive coverage in L-shell and MLT. We found that, within its limitations, this technique could potentially be used to build a dynamic global model of the plasmasp. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021148 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA021148/abstract
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Authors: de Soria-Santacruz M., Li W, Thorne R M, Ma Q, Bortnik J, et al.
Title: Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis
Abstract: A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the POES spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conjunction events with the Van Allen Probes. These amplitudes are calculated with different input models of the plasma density, wave frequency spectrum, and electron energy spectrum, and the results are compared to the wave observations from the twin Van Allen Probes. Only. . .
Date: 04/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020941 Available at: http://doi.wiley.com/10.1002/2014JA020941
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Authors: Hartley D. P., Chen Y., Kletzing C A, Denton M. H., and Kurth W S
Title: Applying the cold plasma dispersion relation to whistler mode chorus waves: EMFISIS wave measurements from the Van Allen Probes
Abstract: Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus wave band (0.1–0.9 fce). Results from this study indicate that the calculated wave intensity is least accurate during periods of enhanced wave activity. For observed wave intensities >10−3 nT2, using the cold plasma dispersi. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020808 Available at: http://doi.wiley.com/10.1002/2014JA020808
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Authors: Mourenas D., Artemyev A. V., and Agapitov O.V.
Title: Approximate analytical formulation of radial diffusion and whistler-induced losses from a pre-existing flux peak in the plasmasphere
Abstract: Modeling the spatio-temporal evolution of relativistic electron fluxes trapped in the Earth's radiation belts in the presence of radial diffusion coupled with wave-induced losses should address one important question: how deep can relativistic electrons penetrate into the inner magnetosphere? However, a full modelling requires extensive numerical simulations solving the comprehensive quasi-linear equations describing pitch-angle and radial diffusion of the electron distribution, making it rather difficult to perform parametric studies of the flux behavior. Here, we consider the particular situation where a localized flux peak (or storage ring) has been produced at low L < 4 during a period of strong disturbances, through a combination of chorus-induced energy diffusion (or direct injection. . .
Date: 08/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021623 Available at: http://doi.wiley.com/10.1002/2015JA021623
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Authors: Claudepierre S G, O'Brien T P, Blake J B, Fennell J. F., Roeder J. L., et al.
Title: A background correction algorithm for Van Allen Probes MagEIS electron flux measurements
Abstract: We describe an automated computer algorithm designed to remove background contamination from the Van Allen Probes MagEIS electron flux measurements. We provide a detailed description of the algorithm with illustrative examples from on-orbit data. We find two primary sources of background contamination in the MagEIS electron data: inner zone protons and bremsstrahlung X-rays generated by energetic electrons interacting with the spacecraft material. Bremsstrahlung X-rays primarily produce contamination in the lower energy MagEIS electron channels (~30-500 keV) and in regions of geospace where multi-MeV electrons are present. Inner zone protons produce contamination in all MagEIS energy channels at roughly L < 2.5. The background corrected MagEIS electron data produce a more accurate me. . .
Date: 06/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021171 Available at: http://doi.wiley.com/10.1002/2015JA021171
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Authors: Chaston C. C., Bonnell J. W., Kletzing C A, Hospodarsky G B, Wygant J R, et al.
Title: Broadband low frequency electromagnetic waves in the inner magnetosphere
Abstract: A prominent yet largely unrecognized feature of the inner magnetosphere associated with particle injections, and more generally geomagnetic storms, is the occurrence of broadband electromagnetic field fluctuations over spacecraft frame frequencies (fsc) extending from effectively zero to fsc ≳ 100 Hz. Using observations from the Van Allen Probes we show that these waves most commonly occur pre-midnight but are observed over a range of local times extending into the dayside magnetosphere. We find that the variation of magnetic spectral energy density with fsc obeys inline image over several decades with a spectral break-point at fb ≈1 Hz. The values for α are log normally distributed with α = 1.9 ± 0.6 for fsc < fb andα = 2.9 ± 0.6 for fsc > fb. A is . . .
Date: 09/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021690 Available at: http://onlinelibrary.wiley.com/wol1/doi/10.1002/2015JA021690/abstract
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Authors: Artemyev A. V., Agapitov O. V., Mozer F S, and Spence H.
Title: Butterfly pitch-angle distribution of relativistic electrons in the outer radiation belt: Evidence of nonadiabatic scattering
Abstract: In this paper we investigate the scattering of relativistic electrons in the night-side outer radiation belt (around the geostationary orbit). We consider the particular case of low geomagnetic activity (|Dst|< 20 nT), quiet conditions in the solar wind, and absence of whistler wave emissions. For such conditions we find several events of Van-Allen probe observations of butterfly pitch-angle distributions of relativistic electrons (energies about 1-3 MeV). Many previous publications have described such pitch-angle distributions over a wide energy range as due to the combined effect of outward radial diffusion and magnetopause shadowing. In this paper we discuss another mechanism that produces butterfly distributions over a limited range of electron energies. We suggest that such distributi. . .
Date: 05/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020865 Available at: http://doi.wiley.com/10.1002/2014JA020865
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Authors: Shprits Yuri Y, Kellerman Adam, Drozdov Alexander, Spense Harlan, Reeves Geoffrey, et al.
Title: Combined Convective and Diffusive Simulations: VERB-4D Comparison with March 17, 2013 Van Allen Probes Observations
Abstract: This study is focused on understanding the coupling between different electron populations in the inner magnetosphere and the various physical processes that determine evolution of electron fluxes at different energies. Observations during the March 17, 2013 storm and simulations with a newly developed Versatile Electron Radiation Belt-4D (VERB-4D) are presented. Analysis of the drift trajectories of the energetic and relativistic electrons shows that electron trajectories at transitional energies with a first invariant on the scale of ~100MeV/G may resemble ring current or relativistic electron trajectories depending on the level of geomagnetic activity. Simulations with the VERB-4D code including convection, radial diffusion, and energy diffusion are presented. Sensitivity simulations in. . .
Date: 09/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL065230 Available at: http://doi.wiley.com/10.1002/2015GL065230
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