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2014
Authors: Zhang J.-C., Saikin A. A., Kistler L. M., Smith C W, Spence H E, et al.
Title: Excitation of EMIC waves detected by the Van Allen Probes on 28 April 2013
Abstract: We report the wave observations, associated plasma measurements, and linear theory testing of electromagnetic ion cyclotron (EMIC) wave events observed by the Van Allen Probes on 28 April 2013. The wave events are detected in their generation regions as three individual events in two consecutive orbits of Van Allen Probe-A, while the other spacecraft, B, does not detect any significant EMIC wave activity during this period. Three overlapping H+ populations are observed around the plasmapause when the waves are excited. The difference between the observational EMIC wave growth parameter (Σh) and the theoretical EMIC instability parameter (Sh) is significantly raised, on average, to 0.10 ± 0.01, 0.15 ± 0.02, and 0.07 ± 0.02 during the three wave events, respectively. On Van A. . .
Date: 06/2014 Publisher: Geophysical Research Letters Pages: 4101–4108 DOI: 10.1002/2014GL060621 Available at: http://doi.wiley.com/10.1002/2014GL060621
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Authors: Su Zhenpeng, Zhu Hui, Xiao Fuliang, Zheng Huinan, Wang Yuming, et al.
Title: Intense duskside lower band chorus waves observed by Van Allen Probes: Generation and potential acceleration effect on radiation belt electrons
Abstract: Local acceleration driven by whistler mode chorus waves largely accounts for the enhancement of radiation belt relativistic electron fluxes, whose favored region is usually considered to be the plasmatrough with magnetic local time approximately from midnight through dawn to noon. On 2 October 2013, the Van Allen Probes recorded a rarely reported event of intense duskside lower band chorus waves (with power spectral density up to 10−3nT2/Hz) in the low-latitude region outside of L=5. Such chorus waves are found to be generated by the substorm-injected anisotropic suprathermal electrons and have a potentially strong acceleration effect on the radiation belt energetic electrons. This event study demonstrates the possibility of broader spatial regions with effective electron acceleration by. . .
Date: 06/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 4266 - 4273 DOI: 10.1002/jgra.v119.610.1002/2014JA019919 Available at: http://doi.wiley.com/10.1002/jgra.v119.6http://doi.wiley.com/10.1002/2014JA019919
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Authors: Mazur J E, O'Brien T P, Looper M D, and Blake J B
Title: Large anisotropies of >60 MeV protons throughout the inner belt observed with the Van Allen Probes mission
Abstract: We report large directional anisotropies of >60 MeV protons using instrumentation on the Van Allen Probes. The combination of a spinning satellite and measurements from the Relativistic Proton Spectrometer instruments that are insensitive to protons outside the instrument field of view together yield a new look at proton radial gradients. The relatively large proton gyroradius at 60 MeV couples with the radial gradients to produce large (maximum ~10:1) flux anisotropies depending on (i) whether the proton guiding center was above or below the Van Allen Probes spacecraft and (ii) the sign of the local flux gradient. In addition to these newly measured anisotropies, below ~2000 km we report a new effect of systematically changing minimum altitude on some proton drift shells that furthe. . .
Date: 06/2014 Publisher: Geophysical Research Letters Pages: 3738 - 3743 DOI: 10.1002/grl.v41.1110.1002/2014GL060029 Available at: http://doi.wiley.com/10.1002/grl.v41.11http://doi.wiley.com/10.1002/2014GL060029
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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: Xiao Fuliang, Yang Chang, He Zhaoguo, Su Zhenpeng, Zhou Qinghua, et al.
Title: Chorus acceleration of radiation belt relativistic electrons during March 2013 geomagnetic storm
Abstract: The recent launching of Van Allen probes provides an unprecedent opportunity to investigate variations of the radiation belt relativistic electrons. During the 17–19 March 2013 storm, the Van Allen probes simultaneously detected strong chorus waves and substantial increases in fluxes of relativistic (2 − 4.5 MeV) electrons around L = 4.5. Chorus waves occurred within the lower band 0.1–0.5fce (the electron equatorial gyrofrequency), with a peak spectral density ∼10−4 nT2/Hz. Correspondingly, relativistic electron fluxes increased by a factor of 102–103 during the recovery phase compared to the main phase levels. By means of a Gaussian fit to the observed chorus spectra, the drift and bounce-averaged diffusion coefficients are calculated and then used to solve a 2-D Fokker-Planc. . .
Date: 05/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 3325 - 3332 DOI: 10.1002/2014JA019822 Available at: http://doi.wiley.com/10.1002/2014JA019822
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Authors: Paulson K. W., Smith C W, Lessard M. R., Engebretson M. J., Torbert R B, et al.
Title: In situ observations of Pc1 pearl pulsations by the Van Allen Probes
Abstract: We present in situ observations of Pc1 pearl pulsations using the Van Allen Probes. These waves are often observed using ground-based magnetometers, but are rarely observed by orbiting satellites. With the Van Allen Probes, we have seen at least 14 different pearl pulsation events during the first year of operations. These new in situ measurements allow us to identify the wave classification based on local magnetic field conditions. Additionally, by using two spacecraft, we are able to observe temporal changes in the region of observation. The waves appear to be generated at an overall central frequency, as often observed on the ground, and change polarization from left- to right-handedness as they propagate into a region where they are resonant with the crossover frequency (where R- and L. . .
Date: 04/2014 Publisher: Geophysical Research Letters Pages: 1823 - 1829 DOI: 10.1002/2013GL059187 Available at: http://doi.wiley.com/10.1002/2013GL059187
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Authors: Agapitov O. V., Artemyev A. V., Mourenas D., Kasahara Y., and Krasnoselskikh V.
Title: Inner belt and slot region electron lifetimes and energization rates based on AKEBONO statistics of whistler waves
Abstract: Global statistics of the amplitude distributions of hiss, lightning-generated, and other whistler mode waves from terrestrial VLF transmitters have been obtained from the EXOS-D (Akebono) satellite in the Earth's plasmasphere and fitted as functions of L and latitude for two geomagnetic activity ranges (Kp<3 and Kp>3). In particular, the present study focuses on the inner zone L∈[1.4,2] where reliable in situ measurements were lacking. Such statistics are critically needed for an accurate assessment of the role and relative dominance of each type of wave in the dynamics of the inner radiation belt. While VLF waves seem to propagate mainly in a ducted mode at L∼1.5–3 for Kp<3, they appear to be substantially unducted during more disturbed periods (Kp>3). Hiss waves are generally the m. . .
Date: 04/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 2876 - 2893 DOI: 10.1002/jgra.v119.410.1002/2014JA019886 Available at: http://doi.wiley.com/10.1002/jgra.v119.4http://doi.wiley.com/10.1002/2014JA019886
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Authors: Mauk Barry H., Sibeck David G., and Kessel Ramona L.
Title: Journal Special Collection Explores Early Results From the Van Allen Probes Mission
Abstract: The processes governing the charged particle populations in the radiation belts encircling Earth have been the subject of intense interest and increasing concern since their discovery by James Van Allen and his team more than 50 years ago [Baker et al., 2013]. Intense interest continues because we still do not know how the various processes work in concert to enhance, remove, and transport particle radiation. Concern is ongoing because the Van Allen radiation belts pose hazards to astronauts and our ever-growing fleet of spacecraft with increasingly sensitive components.
Date: 04/2014 Publisher: Eos, Transactions American Geophysical Union Pages: 112 - 112 DOI: 10.1002/eost.v95.1310.1002/2014EO130007 Available at: http://doi.wiley.com/10.1002/eost.v95.13http://doi.wiley.com/10.1002/2014EO130007
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Authors: Posner A., Hesse M, and Cyr O. C. St.
Title: The main pillar: Assessment of space weather observational asset performance supporting nowcasting, forecasting, and research to operations
Abstract: Space weather forecasting critically depends upon availability of timely and reliable observational data. It is therefore particularly important to understand how existing and newly planned observational assets perform during periods of severe space weather. Extreme space weather creates challenging conditions under which instrumentation and spacecraft may be impeded or in which parameters reach values that are outside the nominal observational range. This paper analyzes existing and upcoming observational capabilities for forecasting, and discusses how the findings may impact space weather research and its transition to operations. A single limitation to the assessment is lack of information provided to us on radiation monitor performance, which caused us not to fully assess (i.e., not as. . .
Date: 04/2014 Publisher: Space Weather Pages: 257 - 276 DOI: 10.1002/swe.v12.410.1002/2013SW001007 Available at: http://doi.wiley.com/10.1002/swe.v12.4http://doi.wiley.com/10.1002/2013SW001007
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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: 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: 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: 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: Yu Yiqun, Koller Josef, Jordanova Vania K., Zaharia Sorin G., Friedel Reinhard W., et al.
Title: Application and testing of the L * neural network with the self-consistent magnetic field model of RAM-SCB
Abstract: We expanded our previous work on L* neural networks that used empirical magnetic field models as the underlying models by applying and extending our technique to drift shells calculated from a physics-based magnetic field model. While empirical magnetic field models represent an average, statistical magnetospheric state, the RAM-SCB model, a first-principles magnetically self-consistent code, computes magnetic fields based on fundamental equations of plasma physics. Unlike the previous L* neural networks that include McIlwain L and mirror point magnetic field as part of the inputs, the new L* neural network only requires solar wind conditions and the Dst index, allowing for an easier preparation of input parameters. This new neural network is compared against those previously trained netwo. . .
Date: 03/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 1683 - 1692 DOI: 10.1002/jgra.v119.310.1002/2013JA019350 Available at: http://doi.wiley.com/10.1002/jgra.v119.3http://doi.wiley.com/10.1002/2013JA019350
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Authors: Turner D. L., Angelopoulos V, Morley S. K., Henderson M G, Reeves G D, et al.
Title: On the cause and extent of outer radiation belt losses during the 30 September 2012 dropout event
Abstract: On 30 September 2012, a flux “dropout” occurred throughout Earth's outer electron radiation belt during the main phase of a strong geomagnetic storm. Using eight spacecraft from NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Van Allen Probes missions and NOAA's Geostationary Operational Environmental Satellites constellation, we examined the full extent and timescales of the dropout based on particle energy, equatorial pitch angle, radial distance, and species. We calculated phase space densities of relativistic electrons, in adiabatic invariant coordinates, which revealed that loss processes during the dropout were > 90% effective throughout the majority of the outer belt and the plasmapause played a key role in limiting the spatial extent . . .
Date: 03/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 1530 - 1540 DOI: 10.1002/2013JA019446 Available at: http://doi.wiley.com/10.1002/2013JA019446
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Authors: Turner D. L., Angelopoulos V, Li W, Bortnik J, Ni B, et al.
Title: Competing source and loss mechanisms due to wave-particle interactions in Earth's outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm
Abstract: Drastic variations of Earth's outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave-particle interactions are critically important. Using 15 spacecraft including NASA's Van Allen Probes, THEMIS, and SAMPEX missions and NOAA's GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm's main phase dropout exhibited enhanced losses to the atmosphere at L* < 4, where the phase space density (PSD) of multi-MeV electrons dropped by over an order of magnitude in <4 h. Based on POES observations of precipitating >1 MeV electrons and energetic protons, SAMPEX >1 MeV electrons, and ground observations of band-limited Pc. . .
Date: 03/2014 Publisher: Journal of Geophysical Research: Space Physics Pages: 1960 - 1979 DOI: 10.1002/jgra.v119.310.1002/2014JA019770 Available at: http://doi.wiley.com/10.1002/jgra.v119.3http://doi.wiley.com/10.1002/2014JA019770
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Authors: Usanova M. E., Drozdov A., Orlova K., Mann I. R., Shprits Y., et al.
Title: Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations
Abstract: We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of >0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both obse. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1375 - 1381 DOI: 10.1002/2013GL059024 Available at: http://doi.wiley.com/10.1002/2013GL059024
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Authors: Tu Weichao, Cunningham G. S., Chen Y., Morley S. K., Reeves G D, et al.
Title: Event-specific chorus wave and electron seed population models in DREAM3D using the Van Allen Probes
Abstract: The DREAM3D diffusion model is applied to Van Allen Probes observations of the fast dropout and strong enhancement of MeV electrons during the October 2012 “double-dip” storm. We show that in order to explain the very different behavior in the two “dips,” diffusion in all three dimensions (energy, pitch angle, and L*) coupled with data-driven, event-specific inputs, and boundary conditions is required. Specifically, we find that outward radial diffusion to the solar wind-driven magnetopause, an event-specific chorus wave model, and a dynamic lower-energy seed population are critical for modeling the dynamics. In contrast, models that include only a subset of processes, use statistical wave amplitudes, or rely on inward radial diffusion of a seed population, perform poorly. The resu. . .
Date: 03/2014 Publisher: Geophysical Research Letters Pages: 1359 - 1366 DOI: 10.1002/2013GL058819 Available at: http://doi.wiley.com/10.1002/2013GL058819
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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: 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: 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: 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: 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: 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: 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: Chen Yue, Reeves Geoffrey D, Friedel Reiner H W, and Cunningham Gregory S.
Title: Global time-dependent chorus maps from low-Earth-orbit electron precipitation and Van Allen Probes data
Abstract: Substorm injected electrons (several–100 s keV) produce whistler-mode chorus waves that are thought to have a major impact on the radiation belts by causing both energization and loss of relativistic electrons in the outer belt. High-altitude measurements, such as those from the Van Allen Probes, provide detailed wave measurements at a few points in the magnetosphere. But physics-based models of radiation-belt dynamics require knowledge of the global distribution of chorus waves. We demonstrate that time-dependent, global distributions of near-equatorial chorus wave intensities can be inferred from low-Earth-orbit (LEO) measurements of precipitating low-energy electrons. We compare in situ observations of near-equatorial chorus waves with LEO observations of precipitating electrons a. . .
Date: 02/2014 Publisher: Geophysical Research Letters Pages: 755 - 761 DOI: 10.1002/2013GL059181 Available at: http://doi.wiley.com/10.1002/2013GL059181
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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: 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: 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: 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: 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: 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: Malaspina D. M., Ergun R. E., Sturner A., Wygant J R, Bonnell J W, et al.
Title: Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape
Abstract: Chorus waves are important for electron energization and loss in Earth's radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation properties are found not to be consistent with plasma density fluctuations on the timescales of individual chorus wave packets. Instead, potential fluctuations are consistent with enhanced photoelectron escape driven by chorus wave electric fields. Enhanced photoelectron escape may result i. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 236 - 243 DOI: 10.1002/2013GL058769 Available at: http://doi.wiley.com/10.1002/2013GL058769
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Authors: O'Brien T P, Claudepierre S G, Blake J B, Fennell J. F., Clemmons J. H., et al.
Title: An empirically observed pitch-angle diffusion eigenmode in the Earth's electron belt near L *  = 5.0
Abstract: Using data from NASA's Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is elastic pitch angle scattering, which itself depends on energy and L*. We invert the shape of the observed eigenmode to obtain an approximate shape of the pitch angle diffusion coefficient and show excellent agreement with diffusion by plasmaspheric hiss. Our results suggest that e. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 251 - 258 DOI: 10.1002/2013GL058713 Available at: http://doi.wiley.com/10.1002/2013GL058713
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Authors: Santolik O, Kletzing C A, Kurth W S, Hospodarsky G B, and Bounds S R
Title: Fine structure of large-amplitude chorus wave packets
Abstract: Whistler mode chorus waves in the outer Van Allen belt can have consequences for acceleration of relativistic electrons through wave-particle interactions. New multicomponent waveform measurements have been collected by the Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science's Waves instrument. We detect fine structure of chorus elements with peak instantaneous amplitudes of a few hundred picotesla but exceptionally reaching up to 3 nT, i.e., more than 1% of the background magnetic field. The wave vector direction turns by a few tens of degrees within a single chorus element but also within its subpackets. Our analysis of a significant number of subpackets embedded in rising frequency elements shows that amplitudes of their peaks tend to decrease with frequ. . .
Date: 01/2014 Publisher: Geophysical Research Letters Pages: 293 - 299 DOI: 10.1002/2013GL058889 Available at: http://doi.wiley.com/10.1002/2013GL058889
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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: 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: 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: 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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2013
Authors: Schultz Colin
Title: Dynamics of the Earth's Radiation Belts and Inner Magnetosphere
Abstract: Trapped by Earth's magnetic field far above the planet's surface, the energetic particles that fill the radiation belts are a sign of the Sun's influence and a threat to our technological future. In the AGU monograph Dynamics of the Earth's Radiation Belts and Inner Magnetosphere, editors Danny Summers, Ian R. Mann, Daniel N. Baker, and Michael Schulz explore the inner workings of the magnetosphere. The book reviews current knowledge of the magnetosphere and recent research results and sets the stage for the work currently being done by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes). In this interview, Eos talks to Summers about magnetospheric research, whistler mode waves, solar storms, and the effects of the radiation belts on Earth.
Date: 12/2013 Publisher: Eos, Transactions American Geophysical Union Pages: 509 - 509 DOI: 10.1002/eost.v94.5210.1002/2013EO520007 Available at: http://doi.wiley.com/10.1002/eost.v94.52http://doi.wiley.com/10.1002/2013EO520007
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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: Mozer F, Bale S., Bonnell J W, Chaston C., Roth I, et al.
Title: Megavolt Parallel Potentials Arising from Double-Layer Streams in the Earth’s Outer Radiation Belt
Abstract: Huge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth’s outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230 000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1 000 000 volts of net parallel potential crossed the spacecraft during this time. A double layer traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, t. . .
Date: 12/2013 Publisher: Physical Review Letters DOI: 10.1103/PhysRevLett.111.235002 Available at: http://link.aps.org/doi/10.1103/PhysRevLett.111.235002
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Authors: Thorne R M, Li W, Ni B, Ma Q, Bortnik J, et al.
Title: Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus
Abstract: Recent analysis of satellite data obtained during the 9 October 2012 geomagnetic storm identified the development of peaks in electron phase space density1, which are compelling evidence for local electron acceleration in the heart of the outer radiation belt2, 3, but are inconsistent with acceleration by inward radial diffusive transport4, 5. However, the precise physical mechanism responsible for the acceleration on 9 October was not identified. Previous modelling has indicated that a magnetospheric electromagnetic emission known as chorus could be a potential candidate for local electron acceleration6, 7, 8, 9, 10, but a definitive resolution of the importance of chorus for radiation-belt acceleration was not possible because of limitations in the energy range and resolution of previous. . .
Date: 12/2013 Publisher: Nature Pages: 411 - 414 DOI: 10.1038/nature12889 Available at: http://www.nature.com/doifinder/10.1038/nature12889
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Authors: Ni Binbin, Bortnik Jacob, Thorne Richard M, Ma Qianli, and Chen Lunjin
Title: Resonant scattering and resultant pitch angle evolution of relativistic electrons by plasmaspheric hiss
Abstract: We perform a comprehensive analysis to evaluate hiss-induced scattering effect on the pitch angle evolution and associated decay processes of relativistic electrons. The results show that scattering by the equatorial, highly oblique hiss component is negligible. Quasi-parallel approximation is good for evaluation of hiss-driven electron scattering rates ≤ 2 MeV. However, realistic wave propagation angles as a function of latitude must be considered to accurately quantify hiss scattering rates above 2 MeV, and ambient plasma density is also a critical parameter. While the first-order cyclotron and the Landau resonances are dominant for hiss scattering < 2 MeV electrons, higher-order resonances become important and even dominant at intermediate pitch angles for ultrarelativistic (≥. . .
Date: 12/2013 Publisher: Journal of Geophysical Research: Space Physics Pages: 7740 - 7751 DOI: 10.1002/2013JA019260 Available at: http://doi.wiley.com/10.1002/2013JA019260
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Authors: Hudson M K
Title: Space physics: A fast lane in the magnetosphere
Abstract: A marriage between satellite observations and modelling has shown that acceleration of electrons in the magnetosphere can be explained by scattering of these particles by plasma oscillations known as chorus waves.
Date: 12/2013 Publisher: Nature Pages: 383 - 384 DOI: 10.1038/504383a Available at: http://www.nature.com/doifinder/10.1038/504383a
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Authors: Ginet G P, ’Brien T P, Huston S L, Johnston W R, Guild T B, et al.
Title: AE9, AP9 and SPM: New Models for Specifying the Trapped Energetic Particle and Space Plasma Environment
Abstract: The radiation belts and plasma in the Earth’s magnetosphere pose hazards to satellite systems which restrict design and orbit options with a resultant impact on mission performance and cost. For decades the standard space environment specification used for spacecraft design has been provided by the NASA AE8 and AP8 trapped radiation belt models. There are well-known limitations on their performance, however, and the need for a new trapped radiation and plasma model has been recognized by the engineering community for some time. To address this challenge a new set of models, denoted AE9/AP9/SPM, for energetic electrons, energetic protons and space plasma has been developed. The new models offer significant improvements including more detailed spatial resolution and the quantification of u. . .
Date: 11/2013 Publisher: Space Science Reviews DOI: 10.1007/s11214-013-9964-y Available at: http://link.springer.com/article/10.1007%2Fs11214-013-9964-y
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