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C
Authors: Cattell C., Breneman A., Colpitts C., Dombeck J., Thaller S., et al.
Title: Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13
Abstract: Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated ExB flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by MMS, with a speed that is comparable to the ExB flow. The magnetopause speed and the ExB speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF. . .
Date: 08/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL074895 Available at: onlinelibrary.wiley.com/doi/10.1002/2017GL074895/full
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Authors: Cattell C. A., Breneman A. W., Thaller S. A., Wygant J R, Kletzing C A, et al.
Title: Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study
Abstract: We show the first evidence for locally excited chorus at frequencies below 0.1 fce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5 fce and f/fce decreases rapidly, often to frequencies well below 0.1 fce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms. . .
Date: 09/2015 Publisher: Geophysical Research Letters Pages: 7273 - 7281 DOI: 10.1002/2015GL065565 Available at: http://doi.wiley.com/10.1002/2015GL065565http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL065565
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Authors: Capannolo L., Li W, Ma Q, Chen L, Shen X.‐C., et al.
Title: Direct Observation of Subrelativistic Electron Precipitation Potentially Driven by EMIC Waves
Abstract: Electromagnetic ion cyclotron (EMIC) waves are known to typically cause electron losses into Earth's upper atmosphere at >~1 MeV, while the minimum energy of electrons subject to efficient EMIC‐driven precipitation loss is unresolved. This letter reports electron precipitation from subrelativistic energies of ~250 keV up to ~1 MeV observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range and Dynamics (FIREBIRD‐II) CubeSats, while two Polar Operational Environmental Satellites (POES) observed proton precipitation nearby. Van Allen Probe A detected EMIC waves (~0.7–2.0 nT) over the similar L shell extent of electron precipitation observed by FIREBIRD‐II, albeit with a ~1.6 magnetic local time (MLT) difference. Although plasmaspheric hiss and magnetosonic . . .
Date: 11/2019 Publisher: Geophysical Research Letters DOI: 10.1029/2019GL084202 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL084202
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Authors: Capannolo L., Li W, Ma Q, Shen X.‐C., Zhang X.‐J., et al.
Title: Energetic Electron Precipitation: Multievent Analysis of Its Spatial Extent During EMIC Wave Activity
Abstract: Electromagnetic ion cyclotron (EMIC) waves can drive precipitation of tens of keV protons and relativistic electrons, and are a potential candidate for causing radiation belt flux dropouts. In this study, we quantitatively analyze three cases of EMIC‐driven precipitation, which occurred near the dusk sector observed by multiple Low‐Earth‐Orbiting (LEO) Polar Operational Environmental Satellites/Meteorological Operational satellite programme (POES/MetOp) satellites. During EMIC wave activity, the proton precipitation occurred from few tens of keV up to hundreds of keV, while the electron precipitation was mainly at relativistic energies. We compare observations of electron precipitation with calculations using quasi‐linear theory. For all cases, we consider the effects of other magn. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026291 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026291
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Authors: Capannolo L., Li W, Ma Q, Zhang X.-J., Redmon R. J., et al.
Title: Understanding the Driver of Energetic Electron Precipitation Using Coordinated Multisatellite Measurements
Abstract: Magnetospheric plasma waves play a significant role in ring current and radiation belt dynamics, leading to pitch angle scattering loss and/or stochastic acceleration of the particles. During a non‐storm time dropout event on 24 September 2013, intense electromagnetic ion cyclotron (EMIC) waves were detected by Van Allen Probe A (Radiation Belt Storm Probes‐A). We quantitatively analyze a conjunction event when Van Allen Probe A was located approximately along the same magnetic field line as MetOp‐01, which detected simultaneous precipitation of >30 keV protons and energetic electrons over an unexpectedly broad energy range (>~30 keV). Multipoint observations together with quasi‐linear theory provide direct evidence that the observed electron precipitation at higher energy (>~700 k. . .
Date: 07/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078604 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078604
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Authors: Cao Xing, Ni Binbin, Summers Danny, Zou Zhengyang, Fu Song, et al.
Title: Bounce resonance scattering of radiation belt electrons by low-frequency hiss: Comparison with cyclotron and Landau resonances
Abstract: Bounce-resonant interactions with magnetospheric waves have been proposed as important contributing mechanisms for scattering near-equatorially mirroring electrons by violating the second adiabatic invariant associated with the electron bounce motion along a geomagnetic field line. This study demonstrates that low-frequency plasmaspheric hiss with significant wave power below 100 Hz can bounce-resonate efficiently with radiation belt electrons. By performing quantitative calculations of pitch-angle scattering rates, we show that low-frequency hiss induced bounce-resonant scattering of electrons has a strong dependence on equatorial pitch-angle αeq. For electrons with αeq close to 90°, the timescale associated with bounce resonance scattering can be comparable to or even less than 1 hour. . .
Date: 09/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL075104 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017GL075104/full
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Authors: Cao Xing, Ni Binbin, Summers Danny, Shprits Yuri Y, Gu Xudong, et al.
Title: Sensitivity of EMIC Wave-Driven Scattering Loss of Ring Current Protons to Wave Normal Angle Distribution
Abstract: Electromagnetic ion cyclotron waves have long been recognized to play a crucial role in the dynamic loss of ring current protons. While the field‐aligned propagation approximation of electromagnetic ion cyclotron waves was widely used to quantify the scattering loss of ring current protons, in this study, we find that the wave normal distribution strongly affects the pitch angle scattering efficiency of protons. Increase of peak normal angle or angular width can considerably reduce the scattering rates of ≤10 keV protons. For >10 keV protons, the field‐aligned propagation approximation results in a pronounced underestimate of the scattering of intermediate equatorial pitch angle protons and overestimates the scattering of high equatorial pitch angle protons by orders of magnitude. Ou. . .
Date: 01/2019 Publisher: Geophysical Research Letters Pages: 590 - 598 DOI: 10.1029/2018GL081550 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL081550
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Authors: Califf S., Li X, Wolf R. A., Zhao H., Jaynes A. N., et al.
Title: Large-amplitude electric fields in the inner magnetosphere: Van Allen Probes observations of subauroral polarization streams
Abstract: The subauroral polarization stream (SAPS) is an important magnetosphere-ionosphere (MI) coupling phenomenon that impacts a range of particle populations in the inner magnetosphere. SAPS studies often emphasize ionospheric signatures of fast westward flows, but the equatorial magnetosphere is also affected through strong radial electric fields in the dusk sector. This study focuses on a period of steady southward interplanetary magnetic field (IMF) during the 29 June 2013 geomagnetic storm where the Van Allen Probes observe a region of intense electric fields near the plasmapause over multiple consecutive outbound duskside passes. We show that the large-amplitude electric fields near the equatorial plane are consistent with SAPS by investigating the relationship between plasma sheet ion and. . .
Date: 05/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA022252 Available at: http://doi.wiley.com/10.1002/2015JA022252
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Authors: Califf S., Li X., Zhao H., Kellerman A., Sarris T. E., et al.
Title: The role of the convection electric field in filling the slot region between the inner and outer radiation belts
Abstract: The Van Allen Probes have reported frequent flux enhancements of 100s keV electrons in the slot region, with lower energy electrons exhibiting more dynamic behavior at lower L shells. Also, in situ electric field measurements from the Combined Release and Radiation Effects Satellite, Time History of Events and Macroscale Interactions during Substorms (THEMIS), and the Van Allen Probes have provided evidence for large-scale electric fields at low L shells during active times. We study an event on 19 February 2014 where hundreds of keV electron fluxes were enhanced by orders of magnitude in the slot region and electric fields of 1–2 mV/m were observed below L = 3. Using a 2-D guiding center particle tracer and a simple large-scale convection electric field model, we demonstrate that . . .
Date: 02/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023657 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016JA023657/full
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Authors: Butler Michael, and Laughery Sean
Title: The RBSP Spacecraft Power System Design and Development
Abstract: The RBSP (Radiation Belt Storm Probes) twin spacecraft are set to launch in August 2012. The spacecraft will be inserted into the highly elliptical regions of high energy particles trapped by the magnetic field of the earth. These regions are often referred to as the Van Allen Belts. The twin spacecraft will operate entirely within the radiation belts throughout their mission. Because of the intense environment of operation and to reduce cost and risk, the approach taken in the power system electronics was to use quasi conventional design, materials, and fabrication techniques encased in a 350mil thick aluminum enclosure. The spacecraft are spin stabilized with an axial boom that creates a shadow across the solar arrays. The power system topology selected was a 28V unregulat. . .
Date: 08/2012 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/MIECEC1210.2514/6.2012-4059 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2012-4059
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Authors: Butler M. H.
Title: The Van Allen Probes Power System Launch and Early Mission Performance
Abstract: The Van Allen Probes are twin NASA spacecraft that were launched August 30, 2012, into lapping highly elliptical earth orbits. The twin spacecraft will operate within the Van Allen radiation belts throughout their two-year mission. The Van Allen Probes are sponsored by NASA’s Living With a Star (LWS) Program. The Johns Hopkins University, Applied Physics Laboratory designed, fabricated, and operates the twin spacecraft for NASA. The power systems of the twin spacecraft are identical. A direct energy transfer topology was selected for the power system. The loads are connected directly to the eight-cell Lithium Ion battery. The solar panels consist of triple junction cells. The design average power of each spacecraft is about 350 Watts, nominal 28.8 volt bus. A single 50 AH . . .
Date: 07/2013 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/MIECEC1310.2514/6.2013-3737 Available at: http://arc.aiaa.org/doi/abs/10.2514/6.2013-3737
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Authors: Bushman Stewart
Title: Design, Fabrication, and Testing of the Radiation Belt Storm Probes Propulsion Systems
Abstract: The Radiation Belt Storm Probes spacecraft , part of NASA’s Living with a Star program, are scheduled for launch into Earth orbit in August 2012. 1,2,3 The twin spacecraft possess identical blowdown monopropellant hydrazine propulsion systems to provide spinup/spindown, precession, Delt a–V, and deorbit capability. Each spacecraft manifests eight Aerojet 0.2 lbf (0.9 N) MR–103G thrust ers, three ARDÉ Inconel 718 propellant tanks, and other components required to control the fl ow of propellant and monitor system health and performance. The propulsion systems were fabricated and installed by Aerojet Redmond and subsequently tested at the Jo hns Hopkins University / Applied Physics Laboratory (APL) in Laurel, MD. The test se quence at APL included thermal balance; . . .
Date: 08/2012 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/6.2012-4332 Available at: http://arc.aiaa.org/doi/abs/10.2514/6.2012-4332
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Authors: Burke W. J., Erickson P. J., Yang J., Foster J., Wygant J, et al.
Title: O + Ion Conic and Plasma Sheet Dynamics Observed by Van Allen Probe Satellites during the 1 June 2013 Magnetic Storm
Abstract: The Van Allen Probe satellites were near apogee in the late evening local time sector during the 1 June 2013 magnetic storm's main phase. About an hour after crossing the ring current's “nose structure” into the plasma sheet, the satellites encountered a quasi-periodic sequence of 0.08 - 3 keV O+ ions. Pitch angle distributions of this population consistently peaked nearly anti-parallel to the local magnetic field. We interpret this population as O+ conics originating in the northern ionosphere. Sequences began as fairly steady state conic fluxes with energies in the ~ 80 to 100 eV range. Over about a half hour build-up phase, O+ energies peaked near 1 keV. During subsequent release phases lasting ~ 20 minutes, O+ energies returned to low-energy starting points. We argu. . .
Date: 05/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2015JA021795 Available at: http://doi.wiley.com/10.1002/2015JA021795
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Authors: Brito Thiago V., and Morley Steven K.
Title: Improving empirical magnetic field models by fitting to in situ data using an optimized parameter approach
Abstract: A method for comparing and optimizing the accuracy of empirical magnetic field models using in situ magnetic field measurements is presented. The optimization method minimizes a cost function - τ - that explicitly includes both a magnitude and an angular term. A time span of 21 days, including periods of mild and intense geomagnetic activity, was used for this analysis. A comparison between five magnetic field models (T96, T01S, T02, TS04, TS07) widely used by the community demonstrated that the T02 model was, on average, the most accurate when driven by the standard model input parameters. The optimization procedure, performed in all models except TS07, generally improved the results when compared to unoptimized versions of the models. Additionally, using more satellites in the optimizat. . .
Date: 10/2017 Publisher: Space Weather DOI: 10.1002/2017SW001702 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017SW001702/full
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Authors: Breneman A. W., Crew A., Sample J., Klumpar D., Johnson A., et al.
Title: Observations Directly Linking Relativistic Electron Microbursts to Whistler Mode Chorus: Van Allen Probes and FIREBIRD II
Abstract: We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising‐tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed. This is the first time that chorus and microbursts have been simultaneously observed with a separation smaller than a chorus packet. A majority of the microbursts do not have t. . .
Date: 11/2017 Publisher: Geophysical Research Letters Pages: 11,265 - 11,272 DOI: 10.1002/2017GL075001 Available at: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL075001
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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: 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: Boyd A.J., Turner D.L., Reeves G.D., Spence H.E., Baker D.N., et al.
Title: What Causes Radiation Belt Enhancements: A Survey of the Van Allen Probes Era
Abstract: We survey radiation belt enhancement events during the Van Allen Probes era to determine what mechanism is the dominant cause of enhancements and where it is most effective. Two primary mechanisms have been proposed: (1) betatron/Fermi acceleration due to the Earthward radial transport of electrons which produces monotonic gradients in phase space density (PSD) and (2) “local acceleration" due to gyro/Landau resonant interaction with electromagnetic waves which produces radially localized, growing peaks in PSD. To differentiate between these processes, we examine radial profiles of PSD in adiabatic coordinates using data from the Van Allen Probes and THEMIS satellites for 80 outer belt enhancement events from October 2012‐April 2017 This study shows that local acceleration is the domin. . .
Date: 05/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL077699 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL077699
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Authors: Boyd A. J., Reeves G D, Spence H E, Funsten H O, Larsen B A, et al.
Title: RBSP‐ECT Combined Spin‐Averaged Electron Flux Data Product
Abstract: We describe a new data product combining the spin‐averaged electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration's Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of spectra for September 2013 to the present. Three‐minute‐averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product provides additional utility to the ECT data and offers a consistent cross calibrated data set for researchers interested in examining the dynamics of the inner magnetosphere across a wide range of energies.
Date: 10/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026733 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026733
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Authors: Boyd A.J., Spence H.E., Huang C.-L., Reeves G D, Baker D N, et al.
Title: Statistical Properties of the Radiation Belt Seed Population
Abstract: We present a statistical analysis of phase space density data from the first 26 months of the Van Allen Probes mission. In particular we investigate the relationship between the 10s-100s keV seed electrons and >1 MeV core radiation belt electron population. Using a cross correlation analysis, we find that the seed and core populations are well correlated with a coefficient of ≈ 0.73 with a time lag of 10-15 hours. We present evidence of a seed population threshold that is necessary for subsequent acceleration. The depth of penetration of the seed population determines the inner boundary of the acceleration process. However, we show that an enhanced seed population alone is not enough to produce acceleration in the higher energies, implying that the seed population of 100s of keV electron. . .
Date: 07/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022652 Available at: http://doi.wiley.com/10.1002/2016JA022652
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Authors: Boardsen Scott A., Hospodarsky George B., Min Kyungguk, Averkamp Terrance F., Bounds Scott R., et al.
Title: Determining the wave vector direction of equatorial fast magnetosonic waves
Abstract: We perform polarization analysis of the equatorial fast magnetosonic waves electric field over a 20 minute interval of Van Allen Probes A Waveform Receiver burst mode data. The wave power peaks at harmonics of the proton cyclotron frequency indicating the spacecraft is near or in the source region. The wave vector is inferred from the direction of the major axis of the electric field polarization ellipsoid and the sign of the phase between the longitudinal electric and compressional magnetic field components. We show that wave vector is preferentially in the azimuthal direction as opposed to the radial direction. From Poynting flux analysis one would infer that the wave vector is primarily in the radial direction. We show that the error in the Poynting flux is large ~ 90°. These results s. . .
Date: 07/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL078695 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078695
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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: Boardsen Scott A, Hospodarsky George B, Kletzing Craig, Engebretson Mark, Pfaff Robert F, et al.
Title: Survey of the Frequency Dependent Latitudinal Distribution of the Fast Magnetosonic Wave Mode from Van Allen Probes EMFISIS Wave Form Receiver Plasma Wave Analysis
Abstract: We present a statistical survey of the latitudinal structure of the fast magnetosonic wave mode detected by the Van Allen Probes spanning the time interval of 9/21/2012 to 8/1/2014. We show that statistically the latitudinal occurrence of the wave frequency (f) normalized by the local proton cyclotron frequency (fcP) has a distinct funnel shaped appearance in latitude about the magnetic equator similar to that found in case studies. By comparing the observed E/B ratios with the model E/B ratio, using the observed plasma density and background magnetic field magnitude as input to the model E/B ratio, we show that this mode is consistent with the extraordinary (whistler) mode at wave normal angles (θk) near 90°. Performing polarization analysis on synthetic waveforms composed from a superp. . .
Date: 02/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021844 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA021844/full
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Authors: Blum L.W., Artemyev A., Agapitov O., Mourenas D., Boardsen S., et al.
Title: EMIC Wave‐Driven Bounce Resonance Scattering of Energetic Electrons in the Inner Magnetosphere
Abstract: While electromagnetic ion cyclotron (EMIC) waves have been long studied as a scattering mechanism for ultrarelativistic (megaelectron volt) electrons via cyclotron‐resonant interactions, these waves are also of the right frequency to resonate with the bounce motion of lower‐energy (approximately tens to hundreds of kiloelectron volts) electrons. Here we investigate the effectiveness of this bounce resonance interaction to better determine the effects of EMIC waves on subrelativistic electron populations in Earth's inner magnetosphere. Using wave and plasma parameters directly measured by the Van Allen Probes, we estimate bounce resonance diffusion coefficients for four different events, illustrative of wave and plasma parameters to be encountered in the inner magnetosphere. The range o. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026427 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026427
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Authors: Blum L. W., Schiller Q., Li X, Millan R., Halford A., et al.
Title: New conjunctive CubeSat and balloon measurements to quantify rapid energetic electron precipitation
Abstract: Relativistic electron precipitation into the atmosphere can contribute significant losses to the outer radiation belt. In particular, rapid narrow precipitation features termed precipitation bands have been hypothesized to be an integral contributor to relativistic electron precipitation loss, but quantification of their net effect is still needed. Here we investigate precipitation bands as measured at low earth orbit by the Colorado Student Space Weather Experiment (CSSWE) CubeSat. Two precipitation bands of MeV electrons were observed on 18–19 January 2013, concurrent with precipitation seen by the 2013 Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) campaign. The newly available conjugate measurements allow for a detailed estimate of the temporal and spatial fea. . .
Date: 11/2013 Publisher: Geophysical Research Letters Pages: 5833 - 5837 DOI: 10.1002/2013GL058546 Available at: http://doi.wiley.com/10.1002/2013GL058546
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Authors: Blum L. W., Agapitov O., Bonnell J. W., Kletzing C., and Wygant J
Title: EMIC wave spatial and coherence scales as determined from multipoint Van Allen Probe measurements
Abstract: Electromagnetic ion cyclotron (EMIC) waves can provide a strong source of energetic electron pitch angle scattering. These waves are often quite localized, thus their spatial extent can have a large effect on their overall scattering efficiency. Using measurements from the dual Van Allen Probes, we examine four EMIC wave events observed simultaneously on the two probes at varying spacecraft separations. Correlation of both the wave amplitude and phase observed at both spacecraft is examined to estimate the active region and coherence scales of the waves. We find well-correlated wave amplitude and amplitude modulation across distances spanning hundreds to thousands of kilometers. Phase coherence persisting 30–60 s is observable during close conjunction events but is lost as spacecraft s. . .
Date: 05/2016 Publisher: Geophysical Research Letters DOI: 10.1002/2016GL068799 Available at: http://doi.wiley.com/10.1002/2016GL068799
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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: Blum L. W., Bonnell J. W., Agapitov O., Paulson K., and Kletzing C.
Title: EMIC wave scale size in the inner magnetosphere: Observations from the dual Van Allen Probes
Abstract: Estimating the spatial scales of electromagnetic ion cyclotron (EMIC) waves is critical for quantifying their overall scattering efficiency and effects on thermal plasma, ring current, and radiation belt particles. Using measurements from the dual Van Allen Probes in 2013–2014, we characterize the spatial and temporal extents of regions of EMIC wave activity and how these depend on local time and radial distance within the inner magnetosphere. Observations are categorized into three types—waves observed by only one spacecraft, waves measured by both spacecraft simultaneously, and waves observed by both spacecraft with some time lag. Analysis reveals that dayside (and H+ band) EMIC waves more frequently span larger spatial areas, while nightside (and He+ band) waves are more often loc. . .
Date: 02/2017 Publisher: Geophysical Research Letters Pages: 1227 - 1233 DOI: 10.1002/2016GL072316 Available at: http://doi.wiley.com/10.1002/2016GL072316
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Authors: Blake J B, Carranza P A, Claudepierre S G, Clemmons J H, Crain W R, et al.
Title: The Magnetic Electron Ion Spectrometer (MagEIS) Instruments Aboard the Radiation Belt Storm Probes (RBSP) Spacecraft
Abstract: This paper describes the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the RBSP spacecraft from an instrumentation and engineering point of view. There are four magnetic spectrometers aboard each of the two spacecraft, one low-energy unit (20–240 keV), two medium-energy units (80–1200 keV), and a high-energy unit (800–4800 keV). The high unit also contains a proton telescope (55 keV–20 MeV). The magnetic spectrometers focus electrons within a selected energy pass band upon a focal plane of several silicon detectors where pulse-height analysis is used to determine if the energy of the incident electron is appropriate for the electron momentum selected by the magnet. Thus each event is a two-parameter analysis, an approach leading to a greatly reduced background. . . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 383-421 DOI: 10.1007/s11214-013-9991-8
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Authors: Bingley L., Angelopoulos V, Sibeck D., Zhang X., and Halford A.
Title: The Evolution of a Pitch‐Angle “Bite‐Out” Scattering Signature Caused by EMIC Wave Activity: A Case Study
Abstract: Electromagnetic ion cyclotron (EMIC) waves are understood to be one of the dominant drivers of relativistic electron loss from Earth's radiation belts. Theory predicts that the associated gyroresonant wave‐particle interaction results in a distinct energy‐dependent “bite‐out” signature in the normalized flux distribution of electrons as they are scattered into the loss cone. We identify such signatures along with the responsible EMIC waves captured in situ by the Van Allen Probes on 15–16 February 2017. Using the cold plasma approximation, we predict the pitch‐angle cutoffs for the scattering signature for the captured EMIC wave and find it in good agreement with the observed electron bite‐out scattering signature. Employing the close conjunction between the Van Allen Probe. . .
Date: 06/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026292 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026292
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Authors: Bingham S. T., Mouikis C. G., Kistler L. M., Boyd A. J., Paulson K., et al.
Title: The outer radiation belt response to the storm time development of seed electrons and chorus wave activity during CME and CIR storms
Abstract: Gyroresonant wave‐particle interactions with very low frequency whistler mode chorus waves can accelerate subrelativistic seed electrons (hundreds of keV) to relativistic energies in the outer radiation belt during geomagnetic storms. In this study, we conduct a superposed epoch analysis of the chorus wave activity, the seed electron development, and the outer radiation belt electron response between L* = 2.5 and 5.5, for 25 coronal mass ejection and 35 corotating interaction region storms using Van Allen Probes observations. Electron data from the Magnetic Electron Ion Spectrometer and Relativistic Electron Proton Telescope instruments are used to monitor the storm‐phase development of the seed and relativistic electrons, and magnetic field measurements from the Electric and Magnetic . . .
Date: 12/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025963 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025963
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Authors: Bin Kang Suk-, Fok Mei-Ching, Komar Colin, Glocer Alex, Li Wen, et al.
Title: An energetic electron flux dropout due to magnetopause shadowing on 1 June 2013
Abstract: We examine the mechanisms responsible for the dropout of energetic electron flux during 31 May – 1 June 2013, using Van Allen Probe (RBSP) electron flux data and simulations with the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. During storm main phase, L-shells at RBSP locations are greater than ~ 8, which are connected to open drift shells. Consequently, diminished electron fluxes were observed over a wide range of energies. The combination of drift shell splitting, magnetopause shadowing and drift loss all result in butterfly electron pitch-angle distributions (PADs) at the nightside. During storm sudden commencement, RBSP observations display electron butterfly PADs over a wide range of energies. However, it is difficult to determine whether there are butterfly PADs duri. . .
Date: 01/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024879 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024879/full
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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: 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: Baker D N, Jaynes A. N., Turner D. L., Nakamura R, Schmid D., et al.
Title: A telescopic and microscopic examination of acceleration in the June 2015 geomagnetic storm: Magnetospheric Multiscale and Van Allen Probes study of substorm particle injection
Abstract: An active storm period in June 2015 showed that particle injection events seen sequentially by the four (Magnetospheric Multiscale) MMS spacecraft subsequently fed the enhancement of the outer radiation belt observed by Van Allen Probes mission sensors. Several episodes of significant southward interplanetary magnetic field along with a period of high solar wind speed (Vsw ≳ 500 km/s) on 22 June occurred following strong interplanetary shock wave impacts on the magnetosphere. Key events on 22 June 2015 show that the magnetosphere progressed through a sequence of energy-loading and stress-developing states until the entire system suddenly reconfigured at 19:32 UT. Energetic electrons, plasma, and magnetic fields measured by the four MMS spacecraft revealed clear dipolarization front. . .
Date: 06/2016 Publisher: Geophysical Research Letters Pages: 6051 - 6059 DOI: 10.1002/grl.v43.1210.1002/2016GL069643 Available at: http://doi.wiley.com/10.1002/2016GL069643
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Authors: Baker D.N., Zhao H., Li X, Kanekal S.G., Jaynes A.N., et al.
Title: Comparison of Van Allen Probes Energetic Electron Data with Corresponding GOES‐15 Measurements: 2012‐2018
Abstract: Electron fluxes (especially at energies E > 0.8 and >2 MeV) have been measured for many years by sensors on board the Geostationary Operational Environmental Satellite (GOES). These long‐term data (nominally at L~6.6) have become a mainstay for monitoring the Earth's radiation environment. We have carried out a study directly comparing the comprehensive radiation belt particle measurements from the NASA dual‐spacecraft Van Allen Probes (Radiation Belt Storm Probes) sensor systems with selected GOES operational data. The Van Allen Probes have measured the properties of radiation belt electrons virtually continuously from September 2012 through 2018. We make statistical comparisons of Van Allen Probes electron data near L=6 with concurrent daily averages of equivalent GOES‐15 flux . . .
Date: 11/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA027331 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA027331
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Authors: Baker D N, Jaynes A. N., Hoxie V C, Thorne R M, Foster J. C., et al.
Title: An impenetrable barrier to ultrarelativistic electrons in the Van Allen radiation belts
Abstract: Early observations1, 2 indicated that the Earth’s Van Allen radiation belts could be separated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies3, 4 showed that electrons of moderate energy (less than about one megaelectronvolt) often populate both zones, with a deep ‘slot’ region largely devoid of particles between them. There is a region of dense cold plasma around the Earth known as the plasmasphere, the outer boundary of which is called the plasmapause. The two-belt radiation structure was explained as arising from strong electron interactions with plasmaspheric hiss just inside the plasmapause boundary5, with the inner edge of the outer radiation zone corresponding to the minimum plasmapause location6. Re. . .
Date: 11/2014 Publisher: Nature Pages: 531 - 534 DOI: 10.1038/nature13956 Available at: http://www.nature.com/doifinder/10.1038/nature13956
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Authors: Baker Daniel N, Hoxie Vaughn, Zhao Hong, Jaynes Allison N., Kanekal Shri, et al.
Title: Multiyear Measurements of Radiation Belt Electrons: Acceleration, Transport, and Loss
Abstract: In addition to clarifying morphological structures of the Earth's radiation belts, it has also been a major achievement of the Van Allen Probes mission to understand more thoroughly how highly relativistic and ultrarelativistic electrons are accelerated deep inside the radiation belts. Prior studies have demonstrated that electrons up to energies of 10 megaelectron volts (MeV) can be produced over broad regions of the outer Van Allen zone on timescales of minutes to a few hours. It often is seen that geomagnetic activity driven by strong solar storms (i.e., coronal mass ejections, or CMEs) almost inexorably leads to relativistic electron production through the intermediary step of intense magnetospheric substorms. In this study, we report observations over the 6‐year period 1 September 2. . .
Date: 03/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA026259 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA026259
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Authors: Baker D N, Jaynes A. N., Li X, Henderson M G, Kanekal S G, et al.
Title: Gradual diffusion and punctuated phase space density enhancements of highly relativistic electrons: Van Allen Probes observations
Abstract: The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E ~10 MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L ~4.0 ± 0.5). Thi. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1351 - 1358 DOI: 10.1002/2013GL058942 Available at: http://doi.wiley.com/10.1002/2013GL058942
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Authors: Baker D N, Kanekal S G, Hoxie V C, Henderson M G, Li X, et al.
Title: A Long-Lived Relativistic Electron Storage Ring Embedded in Earth's Outer Van Allen Belt
Abstract: Since their discovery more than 50 years ago, Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unc. . .
Date: 04/2013 Publisher: Science Pages: 186-190 DOI: 10.1126/science.1233518 Available at: http://www.sciencemag.org/content/340/6129/186
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Authors: Baker D N, Hoxie V C, Jaynes A., Kale A., Kanekal S G, et al.
Title: James Van Allen and His Namesake NASA Mission
Abstract: In many ways, James A. Van Allen defined and “invented” modern space research. His example showed the way for government-university partners to pursue basic research that also served important national and international goals. He was a tireless advocate for space exploration and for the role of space science in the spectrum of national priorities.
Date: 12/2013 Publisher: Eos, Transactions American Geophysical Union Pages: 469 - 470 DOI: 10.1002/eost.v94.4910.1002/2013EO490001 Available at: http://doi.wiley.com/10.1002/eost.v94.49http://doi.wiley.com/10.1002/2013EO490001
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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: Baker D N, Kanekal S G, Hoxie V C, Batiste S, Bolton M, et al.
Title: The Relativistic Electron-Proton Telescope (REPT) Instrument on Board the Radiation Belt Storm Probes (RBSP) Spacecraft: Characterization of Earth’s Radiation Belt High-Energy Particle Populations
Abstract: Particle acceleration and loss in the million electron Volt (MeV) energy range (and above) is the least understood aspect of radiation belt science. In order to measure cleanly and separately both the energetic electron and energetic proton components, there is a need for a carefully designed detector system. The Relativistic Electron-Proton Telescope (REPT) on board the Radiation Belt Storm Probe (RBSP) pair of spacecraft consists of a stack of high-performance silicon solid-state detectors in a telescope configuration, a collimation aperture, and a thick case surrounding the detector stack to shield the sensors from penetrating radiation and bremsstrahlung. The instrument points perpendicular to the spin axis of the spacecraft and measures high-energy electrons (up to ∼20 MeV) with exc. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 337-381 DOI: 10.1007/s11214-012-9950-9 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9950-9
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Authors: Aseev N. A., and Shprits Y Y
Title: Reanalysis of Ring Current Electron Phase Space Densities Using Van Allen Probe Observations, Convection Model, and Log‐Normal Kalman Filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting . . .
Date: 04/2019 Publisher: Space Weather Pages: 619 - 638 DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
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Authors: Aseev N. A., Shprits Y Y, Drozdov A. Y., Kellerman A. C., Usanova M. E., et al.
Title: Signatures of Ultrarelativistic Electron Loss in the Heart of the Outer Radiation Belt Measured by Van Allen Probes
Abstract: Up until recently, signatures of the ultrarelativistic electron loss driven by electromagnetic ion cyclotron (EMIC) waves in the Earth's outer radiation belt have been limited to direct or indirect measurements of electron precipitation or the narrowing of normalized pitch angle distributions in the heart of the belt. In this study, we demonstrate additional observational evidence of ultrarelativistic electron loss that can be driven by resonant interaction with EMIC waves. We analyzed the profiles derived from Van Allen Probe particle data as a function of time and three adiabatic invariants between 9 October and 29 November 2012. New local minimums in the profiles are accompanied by the narrowing of normalized pitch angle distributions and ground-based detection of EMIC waves. Such a cor. . .
Date: 09/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024485 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024485/full
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Authors: Aseev N.A., and Shprits Y.Y.
Title: Reanalysis of ring current electron phase space densities using Van Allen Probe observations, convection model, and log‐normal Kalman filter
Abstract: Models of ring current electron dynamics unavoidably contain uncertainties in boundary conditions, electric and magnetic fields, electron scattering rates, and plasmapause location. Model errors can accumulate with time and result in significant deviations of model predictions from observations. Data assimilation offers useful tools which can combine physics‐based models and measurements to improve model predictions. In this study, we systematically analyze performance of the Kalman filter applied to a log‐transformed convection model of ring current electrons and Van Allen Probe data. We consider long‐term dynamics of μ = 2.3 MeV/G and K = 0.3 G1/2RE electrons from 1 February 2013 to 16 June 2013. By using synthetic data, we show that the Kalman filter is capable of correcting erro. . .
Date: 04/2019 Publisher: Space Weather DOI: 10.1029/2018SW002110 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW002110
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Authors: Aryan Homayon, Sibeck David G., Bin Kang Suk-, Balikhin Michael A., Fok Mei-Ching, et al.
Title: CIMI simulations with newly developed multi-parameter chorus and plasmaspheric hiss wave models
Abstract: Numerical simulation studies of the Earth's radiation belts are important to understand the acceleration and loss of energetic electrons. The Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model considers the effects of the ring current and plasmasphere on the radiation belts to obtain plausible results. The CIMI model incorporates pitch angle, energy, and cross diffusion of electrons, due to chorus and plasmaspheric hiss waves. These parameters are calculated using statistical wave distribution models of chorus and plasmaspheric hiss amplitudes. However, currently these wave distribution models are based only on a single parameter, geomagnetic index (AE), and could potentially underestimate the wave amplitudes. Here we incorporate recently developed multi-parameter chorus and plasmas. . .
Date: 08/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024159 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024351/full
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Authors: Aryan Homayon, Sibeck David, Balikhin Michael, Agapitov Oleksiy, and Kletzing Craig
Title: Observation of chorus waves by the Van Allen Probes: Dependence on solar wind parameters and scale size
Abstract: Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not onl. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: 7608 - 7621 DOI: 10.1002/jgra.v121.810.1002/2016JA022775 Available at: http://doi.wiley.com/10.1002/2016JA022775
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Authors: Artemyev A. V., Mourenas D., Agapitov O. V., and Blum L.
Title: Transverse eV ion heating by random electric field fluctuations in the plasmasphere
Abstract: Charged particle acceleration in the Earth inner magnetosphere is believed to be mainly due to the local resonant wave-particle interaction or particle transport processes. However, the Van Allen Probes have recently provided interesting evidence of a relatively slow transverse heating of eV ions at distances about 2–3 Earth radii during quiet times. Waves that are able to resonantly interact with such very cold ions are generally rare in this region of space, called the plasmasphere. Thus, non-resonant wave-particle interactions are expected to play an important role in the observed ion heating. We demonstrate that stochastic heating by random transverse electric field fluctuations of whistler (and possibly electromagnetic ion cyclotron) waves could explain this weak and slow transverse. . .
Date: 02/2017 Publisher: Physics of Plasmas DOI: 10.1063/1.4976713 Available at: http://aip.scitation.org/doi/abs/10.1063/1.4976713
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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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