Biblio

Found 879 results
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 
E
Authors: Yu Xiongdong, Yuan Zhigang, Huang Shiyong, Yao Fei, Wang Dedong, et al.
Title: Excitation of O + Band EMIC Waves Through H + Ring Velocity Distributions: Van Allen Probe Observations
Abstract: A typical case of electromagnetic ion cyclotron (EMIC) emissions with both He+ band and O+ band waves was observed by Van Allen Probe A on 14 July 2014. These emissions occurred in the morning sector on the equator inside the plasmasphere, in which region O+ band EMIC waves prefer to appear. Through property analysis of these emissions, it is found that the He+ band EMIC waves are linearly polarized and propagating quasi-parallelly along the background magnetic field, while the O+ band ones are of linear and left-hand polarization and propagating obliquely with respect to the background magnetic field. Using the in situ observations of plasma environment and particle data, excitation of these O+ band EMIC waves has been investigated with the linear growth theory. The calculated linear grow. . .
Date: 02/2018 Publisher: Geophysical Research Letters Pages: 1271 - 1276 DOI: 10.1002/grl.v45.310.1002/2018GL077109 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2018GL077109/full
More Details
Authors: Dai L, Takahashi K, Wygant J R, Chen L, Bonnell J W, et al.
Title: Excitation of Poloidal standing Alfven waves through the drift resonance wave-particle interaction
Abstract: Drift-resonance wave-particle interaction is a fundamental collisionless plasma process studied extensively in theory. Using cross-spectral analysis of electric field, magnetic field, and ion flux data from the Van Allen Probe (Radiation Belt Storm Probes) spacecraft, we present direct evidence identifying the generation of a fundamental mode standing poloidal wave through drift-resonance interactions in the inner magnetosphere. Intense azimuthal electric field (Eφ) oscillations as large as 10mV/m are observed, associated with radial magnetic field (Br) oscillations in the dawn-noon sector near but south of the magnetic equator at L∼5. The observed wave period, Eφ/Br ratio and the 90° phase lag between Br and Eφ are all consistent with fundamental mode standing Poloidal waves. Phase . . .
Date: 08/2013 Publisher: Geophysical Research Letters DOI: 10.1002/grl.50800 Available at: http://onlinelibrary.wiley.com/doi/10.1002/grl.50800/full
More Details
Authors: Chelpanov Maksim A., Mager Pavel N., Klimushkin Dmitri Yu., Berngardt Oleg I., and Mager Olga V.
Title: Experimental evidence of drift compressional waves in the magnetosphere: an Ekaterinburg coherent decameter radar case study
Abstract: A case study of shortwave radar observations of magnetospheric Pc5 ULF waves (wave periods of 150–600 s) that occurred on 26 December 2014 in the nightside magnetosphere during substorm activity is presented. The radar study of waves in the magnetosphere is based on analysis of scattering from field-aligned irregularities of the ionospheric F layer. Variations of their inline image drift velocity at F layer heights are associated with the wave electric field. Analysis of the observations from the Ekaterinburg (EKB) radar shows that the frequency f of the observed wave depends on the azimuthal wave number m (positive correlation of about 0.90): an increase in frequency from 2.5 to 5 mHz corresponds to increased m number from 20 to 80. Of the known types of waves in the magnetosphere corre. . .
Date: 02/2016 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA022155 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015JA022155/full
More Details
Authors: Xiao Fuliang, Zhou Qinghua, Su Zhenpeng, He Zhaoguo, Yang Chang, et al.
Title: Explaining occurrences of auroral kilometric radiation in Van Allen radiation belts
Abstract: Auroral kilometric radiation (AKR) is a strong terrestrial radio emission and dominates at higher latitudes because of reflection in vicinities of the source cavity and plasmapause. Recently, Van Allen Probes have observed occurrences of AKR emission in the equatorial region of Earth's radiation belts but its origin still remains an open question. Equatorial AKR can produce efficient acceleration of radiation belt electrons and is a risk to space weather. Here we report high-resolution observations during two small storm periods 4–6 April and 18–20 May 2013 and show, using a 3-D ray tracing simulation, that AKR can propagate downward all the way into the equatorial plane in the radiation belts under appropriate conditions. The simulated results can successfully explain the observed AKR. . .
Date: 12/2016 Publisher: Geophysical Research Letters Pages: 11,971 - 11,978 DOI: 10.1002/2016GL071728 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2016GL071728/full
More Details
Authors: Turner Drew L, Shprits Yuri, Hartinger Michael, and Angelopoulos Vassilis
Title: Explaining sudden losses of outer radiation belt electrons during geomagnetic storms
Abstract: The Van Allen radiation belts were first discovered in 1958 by the Explorer series of spacecraft1. The dynamic outer belt consists primarily of relativistic electrons trapped by the Earth’s magnetic field. Magnetospheric processes driven by the solar wind2 cause the electron flux in this belt to fluctuate substantially over timescales ranging from minutes to years3. The most dramatic of these events are known as flux ’dropouts’ and often occur during geomagnetic storms. During such an event the electron flux can drop by several orders of magnitude in just a few hours4, 5 and remain low even after a storm has abated. Various solar wind phenomena, including coronal mass ejections and co-rotating interaction regions6, can drive storm activity, but several outstanding questions remain co. . .
Date: 01/2012 Publisher: Nature Publishing Group Pages: 208–212 DOI: 10.1038/nphys2185 Available at: http://dx.doi.org/10.1038/nphys2185
More Details
Authors: Mann I. R., Ozeke L. G., Murphy K. R., Claudepierre S G, Turner D. L., et al.
Title: Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt
Abstract: Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a datadriven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt is established as a simple, elegant consequence o. . .
Date: 06/2016 Publisher: Nature Physics DOI: 10.1038/nphys3799 Available at: http://www.nature.com/doifinder/10.1038/nphys3799
More Details
Authors: Takahashi Kazue, Denton Richard E, Kurth William, Kletzing Craig, Wygant John, et al.
Title: Externally driven plasmaspheric ULF waves observed by the Van Allen Probes
Abstract: We analyze data acquired by the Van Allen Probes on 8 November 2012, during a period of extended low geomagnetic activity, to gain new insight into plasmaspheric ultra-low-frequency (ULF) waves. The waves exhibited strong spectral power in the 5–40 mHzband and included multiharmonic toroidal waves visible up to the 11th harmonic, unprecedented in the plasmasphere. During this wave activity, the interplanetary magnetic field cone angle was small, suggesting that the waves were driven by broadband compressional ULF waves originating in the foreshock region. This source mechanism is supported by the tailward propagation of the compressional magnetic field perturbations at a phase velocity of a few hundred kilometers per second that is determined bythe cross phase analysis of data from the t. . .
Date: 12/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020373 Available at: http://doi.wiley.com/10.1002/2014JA020373
More Details
Authors: Takahashi Kazue, Denton Richard E., Kurth William, Kletzing Craig, Wygant John, et al.
Title: Externally driven plasmaspheric ULF waves observed by the Van Allen Probes
Abstract: We analyze data acquired by the Van Allen Probes on 8 November 2012, during a period of extended low geomagnetic activity, to gain new insight into plasmaspheric ultralow frequency (ULF) waves. The waves exhibited strong spectral power in the 5–40 mHz band and included multiharmonic toroidal waves visible up to the eleventh harmonic, unprecedented in the plasmasphere. During this wave activity, the interplanetary magnetic field cone angle was small, suggesting that the waves were driven by broadband compressional ULF waves originating in the foreshock region. This source mechanism is supported by the tailward propagation of the compressional magnetic field perturbations at a phase velocity of a few hundred kilometers per second that is determined by the cross-phase analysis of data from . . .
Date: 01/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020373 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2014JA020373
More Details
Authors: Baker D N, Kanekal S G, Li X, Monk S P, Goldstein J, et al.
Title: An extreme distortion of the Van Allen belt arising from the ‘Hallowe’en’ solar storm in 2003
Abstract: The Earth's radiation belts—also known as the Van Allen belts1—contain high-energy electrons trapped on magnetic field lines2, 3. The centre of the outer belt is usually 20,000–25,000 km from Earth. The region between the belts is normally devoid of particles2, 3, 4, and is accordingly favoured as a location for spacecraft operation because of the benign environment5. Here we report that the outer Van Allen belt was compressed dramatically by a solar storm known as the ‘Hallowe'en storm’ of 2003. From 1 to 10 November, the outer belt had its centre only ~10,000 km from Earth's equatorial surface, and the plasmasphere was similarly displaced inwards. The region between the belts became the location of high particle radiation intensity. This remarkable deformation of the entire. . .
Date: 12/2004 Publisher: Nature Pages: 878 - 881 DOI: 10.1038/nature03116 Available at: http://www.nature.com/nature/journal/v432/n7019/full/nature03116.html
More Details
Authors: Lugaz N., Farrugia C. J., Huang C.-L., and Spence H E
Title: Extreme geomagnetic disturbances due to shocks within CMEs
Abstract: We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth's magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large . . .
Date: 06/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064530 Available at: http://doi.wiley.com/10.1002/2015GL064530
More Details
Authors: Chaston C. C., Bonnell J. W., Wygant J R, Kletzing C A, Reeves G D, et al.
Title: Extreme ionospheric ion energization and electron heating in Alfvén waves in the storm-time inner magnetosphere
Abstract: We report measurements of energized outflowing/bouncing ionospheric ions and heated electrons in the inner magnetosphere during a geomagnetic storm. The ions arrive in the equatorial plane with pitch angles that increase with energy over a range from tens of eV to > 50 keV while the electrons are field-aligned up to ~1 keV. These particle distributions are observed during intervals of broadband low frequency electromagnetic field fluctuations consistent with a Doppler-shifted spectrum of kinetic Alfvén waves and kinetic field-line resonances. The fluctuations extend from L≈3 out to the apogee of the Van Allen Probes spacecraft at L≈6.5. They thereby span most of the L-shell range occupied by the ring current. These measurements suggest a model for ionospheric ion outflow and energizat. . .
Date: 12/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL066674 Available at: http://doi.wiley.com/10.1002/2015GL066674http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015GL066674
More Details
F
Authors: Wang Chengrui, Rankin Robert, and Zong Qiugang
Title: Fast damping of ultralow frequency waves excited by interplanetary shocks in the magnetosphere
Abstract: Analysis of Cluster spacecraft data shows that intense ultralow frequency (ULF) waves in the inner magnetosphere can be excited by the impact of interplanetary shocks and solar wind dynamic pressure variations. The observations reveal that such waves can be damped away rapidly in a few tens of minutes. Here we examine mechanisms of ULF wave damping for two interplanetary shocks observed by Cluster on 7 November 2004 and 30 August 2001. The mechanisms considered are ionospheric joule heating, Landau damping, and waveguide energy propagation. It is shown that Landau damping provides the dominant ULF wave damping for the shock events of interest. It is further demonstrated that damping is caused by drift-bounce resonance with ions in the energy range of a few keV. Landau damping is shown to b. . .
Date: 03/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020761 Available at: http://doi.wiley.com/10.1002/2014JA020761
More Details
Authors: Jaynes A. N., Ali A. F., Elkington S R, Malaspina D. M., Baker D N, et al.
Title: Fast diffusion of ultra-relativistic electrons in the outer radiation belt: 17 March 2015 storm event
Abstract: Inward radial diffusion driven by ULF waves has long been known to be capable of accelerating radiation belt electrons to very high energies within the heart of the belts, but more recent work has shown that radial diffusion values can be highly event‐specific and mean values or empirical models may not capture the full significance of radial diffusion to acceleration events. Here we present an event of fast inward radial diffusion, occurring during a period following the geomagnetic storm of 17 March 2015. Ultra‐relativistic electrons up to ∼8 MeV are accelerated in the absence of intense higher‐frequency plasma waves, indicating an acceleration event in the core of the outer belt driven primarily or entirely by ULF wave‐driven diffusion. We examine this fast diffusion rate alon. . .
Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079786 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079786
More Details
Authors: Min Kyungguk, Liu Kaijun, Wang Xueyi, Chen Lunjin, and Denton Richard E
Title: Fast Magnetosonic Waves Observed by Van Allen Probes: Testing Local Wave Excitation Mechanism
Abstract: Linear Vlasov theory and particle-in-cell (PIC) simulations for electromagnetic fluctuations in a homogeneous, magnetized, and collisionless plasma are used to investigate a fast magnetosonic wave event observed by the Van Allen Probes. The fluctuating magnetic field observed exhibits a series of spectral peaks at harmonics of the proton cyclotron frequency Ωp and has a dominant compressional component, which can be classified as fast magnetosonic waves. Furthermore, the simultaneously observed proton phase space density exhibits positive slopes in the perpendicular velocity space, ∂fp/∂v⊥>0, which can be a source for these waves. Linear theory analyses and PIC simulations use plasma and field parameters measured in situ except that the modeled proton distribution is modified to hav. . .
Date: 01/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2017JA024867 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017JA024867/full
More Details
Authors: Ozaki M., Shiokawa K., Miyoshi Y, Kataoka R., Yagitani S., et al.
Title: Fast modulations of pulsating proton aurora related to subpacket structures of Pc1 geomagnetic pulsations at subauroral latitudes
Abstract: To understand the role of electromagnetic ion cyclotron (EMIC) waves in determining the temporal features of pulsating proton aurora (PPA) via wave-particle interactions at subauroral latitudes, high-time-resolution (1/8 s) images of proton-induced N2+ emissions were recorded using a new electron multiplying charge-coupled device camera, along with related Pc1 pulsations on the ground. The observed Pc1 pulsations consisted of successive rising-tone elements with a spacing for each element of 100 s and subpacket structures, which manifest as amplitude modulations with a period of a few tens of seconds. In accordance with the temporal features of the Pc1 pulsations, the auroral intensity showed a similar repetition period of 100 s and an unpredicted fast modulation of a few tens of sec. . .
Date: 08/2016 Publisher: Geophysical Research Letters Pages: 7859 - 7866 DOI: 10.1002/2016GL070008 Available at: http://doi.wiley.com/10.1002/2016GL070008
More Details
Authors: Artemyev A. V., Vasiliev A. A., Mourenas D., Agapitov O. V., Krasnoselskikh V., et al.
Title: Fast transport of resonant electrons in phase space due to nonlinear trapping by whistler waves
Abstract: We present an analytical, simplified formulation accounting for the fast transport of relativistic electrons in phase space due to wave-particle resonant interactions in the inhomogeneous magnetic field of Earth's radiation belts. We show that the usual description of the evolution of the particle velocity distribution based on the Fokker-Planck equation can be modified to incorporate nonlinear processes of wave-particle interaction, including particle trapping. Such a modification consists in one additional operator describing fast particle jumps in phase space. The proposed, general approach is used to describe the acceleration of relativistic electrons by oblique whistler waves in the radiation belts. We demonstrate that for a wave power distribution with a hard enough power law tail in. . .
Date: 08/2014 Publisher: Geophysical Research Letters Pages: 5727 - 5733 DOI: 10.1002/grl.v41.1610.1002/2014GL061380 Available at: http://doi.wiley.com/10.1002/grl.v41.16http://doi.wiley.com/10.1002/2014GL061380
More Details
Authors: McKenna-Lawlor Susan
Title: Feasibility study of astronaut standardized career dose limits in LEO and the outlook for BLEO
Abstract: Cosmic Study Group SG 3.19/1.10 was established in February 2013 under the aegis of the International Academy of Astronautics to consider and compare the dose limits adopted by various space agencies for astronauts in Low Earth Orbit. A preliminary definition of the limits that might later be adopted by crews exploring Beyond Low Earth Orbit was, in addition, to be made. The present paper presents preliminary results of the study reported at a Symposium held in Turin by the Academy in July 2013. First, an account is provided of exposure limits assigned by various partner space agencies to those of their astronauts that work aboard the International Space Station. Then, gaps in the scientific and technical information required to safely implement human missions beyond the shielding provided. . .
Date: 11/2014 Publisher: Acta Astronautica Pages: 565 - 573 DOI: 10.1016/j.actaastro.2014.07.011 Available at: http://linkinghub.elsevier.com/retrieve/pii/S0094576514002549http://api.elsevier.com/content/article/PII:S0094576514002549?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0094576514002549?httpAccept=text/plain
More Details
Authors: Breuillard H., Agapitov O., Artemyev A., Kronberg E. A., Haaland S. E., et al.
Title: Field-aligned chorus wave spectral power in Earth's outer radiation belt
Abstract: Chorus-type whistler waves are one of the most intense electromagnetic waves generated naturally in the magnetosphere. These waves have a substantial impact on the radiation belt dynamics as they are thought to contribute to electron acceleration and losses into the ionosphere through resonant wave–particle interaction. Our study is devoted to the determination of chorus wave power distribution on frequency in a wide range of magnetic latitudes, from 0 to 40°. We use 10 years of magnetic and electric field wave power measured by STAFF-SA onboard Cluster spacecraft to model the initial (equatorial) chorus wave spectral power, as well as PEACE and RAPID measurements to model the properties of energetic electrons (~ 0.1–100 keV) in the outer radiation belt. The dependence of this distrib. . .
Date: 01/2015 Publisher: Annales Geophysicae Pages: 583 - 597 DOI: 10.5194/angeo-33-583-2015 Available at: http://www.ann-geophys.net/33/583/2015/http://www.ann-geophys.net/33/583/2015/angeo-33-583-2015.pdf
More Details
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
More Details
Authors: Summers Danny, Omura Yoshiharu, Nakamura Satoko, and Kletzing Craig A.
Title: Fine structure of plasmaspheric hiss
Abstract: Plasmaspheric hiss has been widely regarded as a broadband, structureless, incoherent emission. In this study, by examining burst-mode vector waveform data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on the Van Allen Probes mission, we show that plasmaspheric hiss is a coherent emission with complex fine structure. Specifically, plasmaspheric hiss appears as discrete rising tone and falling tone elements. Our study comprises the analysis of two one-hour samples within which a total of 8 one-second samples were analyzed. By means of waveform analysis on two samples we identify typical amplitudes, phase profiles, and sweep rates of the rising and falling tone elements. The exciting new observations reported here can be expected to fuel a . . .
Date: 12/2014 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020437 Available at: http://doi.wiley.com/10.1002/2014JA020437
More Details
Authors: Nakamura S., Omura Y., and Summers D.
Title: Fine structure of whistler-mode hiss in plasmaspheric plumes observed by the Van Allen Probes
Abstract: We survey 3 years (2013‐2015) of data from the Van Allen Probes related to plasmaspheric plume crossing events. We detect 194 plume crossing events, and we find that 97% of the plumes are accompanied by VLF hiss emissions. The plumes are mainly detected on the duskside or dayside. Careful examination of the hiss spectra reveals that all hiss emissions consist of obvious fine structure. Application of a band pass filter reveals that the fine structure is consistent with the occurrence of discrete wave packets. The hiss data display high coherency. The events are classified by location. Dusk side hiss and night side hiss tend to have extremely high polarization with no chorus at the high‐frequency end of the dynamic spectrum. The dusk side hiss has a distinct upper frequency limit. On th. . .
Date: 10/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025803 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025803
More Details
Authors: Li W, Chen L, Bortnik J, Thorne R M, Angelopoulos V, et al.
Title: First Evidence for Chorus at a Large Geocentric Distance as a Source of Plasmaspheric Hiss: Coordinated THEMIS and Van Allen Probes Observation
Abstract: Recent ray tracing suggests that plasmaspheric hiss can originate from chorus observed outside of the plasmapause. Although a few individual events have been reported to support this mechanism, the number of reported conjugate events is still very limited. Using coordinated observations between THEMIS and Van Allen Probes, we report on an interesting event, where chorus was observed at a large L-shell (~9.8), different from previously reported events at L < 6, but still exhibited a remarkable correlation with hiss observed in the outer plasmasphere (L ~ 5.5). Ray tracing indicates that a subset of chorus can propagate into the observed location of hiss on a timescale of ~ 5-6 s, in excellent agreement with the observed time lag between chorus and hiss. This provides quantitative support th. . .
Date: 01/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL062832 Available at: http://doi.wiley.com/10.1002/2014GL062832
More Details
Authors: Valek P. W., Goldstein J, Jahn J -M, McComas D J, and Spence H E
Title: First joint in situ and global observations of the medium-energy oxygen and hydrogen in the inner magnetosphere
Abstract: We present the first simultaneous observations of the in situ ions and global Energetic Neutral Atom (ENA) images of the composition-separated, medium-energy (~1–50 keV) particle populations of the inner magnetosphere. The ENA emissions are mapped into L shell/magnetic local time space based on the exospheric density along the line of sight (LOS). The ENA measurement can then be scaled to determine an average ion flux along a given LOS. The in situ ion flux tends to be larger than the scaled ENAs at the same local time. This indicates that the ion population is more concentrated in the Van Allen Probes orbital plane than distributed along the Two Wide-angle Imaging Neutral-atom Spectrometers LOS. For the large storm of 14 November 2012, we observe that the concentration of O (in situ i. . .
Date: 09/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 7615 - 7628 DOI: 10.1002/2015JA021151 Available at: http://doi.wiley.com/10.1002/2015JA021151http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021151
More Details
Authors: Fu H. S., Cao J. B., Zhima Z., Khotyaintsev Y. V., Angelopoulos V, et al.
Title: First observation of rising-tone magnetosonic waves
Abstract: Magnetosonic (MS) waves are linearly polarized emissions confined near the magnetic equator with wave normal angle near 90° and frequency below the lower hybrid frequency. Such waves, also termed equatorial noise, were traditionally known to be “temporally continuous” in their time-frequency spectrogram. Here we show for the first time that MS waves actually have discrete wave elements with rising-tone features in their spectrogram. The frequency sweep rate of MS waves, ~1 Hz/s, is between that of chorus and electromagnetic ion cyclotron (EMIC) waves. For the two events we analyzed, MS waves occur outside the plasmapause and cannot penetrate into the plasmasphere; their power is smaller than that of chorus. We suggest that the rising-tone feature of MS waves is a consequence of nonl. . .
Date: 11/2014 Publisher: Geophysical Research Letters Pages: 7419 - 7426 DOI: 10.1002/grl.v41.2110.1002/2014GL061867 Available at: http://doi.wiley.com/10.1002/grl.v41.21http://doi.wiley.com/10.1002/2014GL061867
More Details
Authors: Li X, Schiller Q., Blum L., Califf S., Zhao H., et al.
Title: First Results from CSSWE CubeSat: Characteristics of Relativistic Electrons in the Near-Earth Environment During the October 2012 Magnetic Storms
Abstract: Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board the Colorado Student Space Weather Experiment (CSSWE) CubeSat mission, which was launched into a highly inclined (65°) low Earth orbit, are analyzed along with measurements from the Relativistic Electron and Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes, which are in a low inclination (10°) geo-transfer-like orbit. Both REPT and MagEIS measure the full distribution of energetic electrons as they traverse the heart of the outer radiation belt. However, due to the small equatorial loss cone (only a few degrees), it is difficult for REPT and MagEIS to directly determine which electrons will precipitate into the. . .
Date: 10/2013 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2013JA019342 Available at: http://doi.wiley.com/10.1002/2013JA019342
More Details
Authors: Maurer R H, Goldsten J O, Butler M. H., and Fretz K.
Title: Five Year Results from the Engineering Radiation Monitor (ERM) and Solar Cell Monitor on the Van Allen Probes Mission
Abstract: The Engineering Radiation Monitor (ERM) measures dose, dose rate and charging currents on the Van Allen Probes mission to study the dynamics of Earth's Van Allen radiation belts. Over five years, results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data and a comparison of cumulative dose to pre‐launch modeling. Solar cell degradation monitor patches track the decrease in solar array output as displacement damage accumulates. The Solar Cell Monitor shows ~33% cumulative degradation in maximum power after 5.1 years of the mission. The desire to extend the mission to ~2500 days from 800 days created increased requirements for the ionizing radiation hardness of spacecraft and science instrument electronics. We describe . . .
Date: 09/2018 Publisher: Space Weather DOI: 10.1029/2018SW001910 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018SW001910
More Details
Authors: Chen Yue, Reeves Geoffrey D, Cunningham Gregory S., Redmon Robert J., and Henderson Michael G.
Title: Forecasting and remote sensing outer belt relativistic electrons from low Earth orbit
Abstract: This study demonstrates the feasibility and reliability of using observations from low Earth orbit (LEO) to forecast and nowcast relativistic electrons in the outer radiation belt. We first report a high cross-energy, cross-pitch-angle coherence discovered between the trapped MeV electrons and precipitating approximately hundreds (~100s) of keV electrons—observed by satellites with very different altitudes—with correlation coefficients as high as ≳ 0.85. Based upon the coherence, we then tested the feasibility of applying linear prediction filters to LEO data to predict the arrival of new MeV electrons during geomagnetic storms, as well as their evolving distributions afterward. Reliability of these predictive filters is quantified by the performance efficiency with values as high . . .
Date: 02/2016 Publisher: Geophysical Research Letters Pages: 1031 - 1038 DOI: 10.1002/2015GL067481 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2015GL067481/full
More Details
Authors: Motoba T., Ohtani S, Anderson B J, Korth H., Mitchell D., et al.
Title: On the formation and origin of substorm growth phase/onset auroral arcs inferred from conjugate space-ground observations
Abstract: Magnetotail processes and structures related to substorm growth phase/onset auroral arcs remain poorly understood mostly due to the lack of adequate observations. In this study we make a comparison between ground-based optical measurements of the premidnight growth phase/onset arcs at subauroral latitudes and magnetically conjugate measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) at ~780 km in altitude and by the Van Allen Probe B (RBSP-B) spacecraft crossing L values of ~5.0–5.6 in the premidnight inner tail region. The conjugate observations offer a unique opportunity to examine the detailed features of the arc location relative to large-scale Birkeland currents and of the magnetospheric counterpart. Our main findings include (1. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 8707 - 8722 DOI: 10.1002/jgra.v120.1010.1002/2015JA021676 Available at: http://doi.wiley.com/10.1002/jgra.v120.10http://doi.wiley.com/10.1002/2015JA021676http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021676
More Details
Authors: Li Jinxing, Ni Binbin, Ma Qianli, Xie Lun, Pu Zuyin, et al.
Title: Formation of Energetic Electron Butterfly Distributions by Magnetosonic Waves via Landau Resonance
Abstract: Radiation belt electrons can exhibit different types of pitch angle distributions in response to various magnetospheric processes. Butterfly distributions, characterized by flux minima at pitch angles around 90°, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause. However, their occurrence in the inner belt and the slot region has hitherto not been resolved. By analyzing the particle and wave data collected by the Van Allen Probes during a geomagnetic storm, we combine test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation. . .
Date: 04/2016 Publisher: Geophysical Research Letters Pages: n/a - n/a DOI: 10.1002/2016GL067853 Available at: http://doi.wiley.com/10.1002/2016GL067853http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2016GL067853
More Details
Authors: Su Yi-Jiun, Selesnick Richard S., and Blake J B
Title: Formation of the inner electron radiation belt by enhanced large-scale electric fields
Abstract: A two-dimensional bounce-averaged test particle code was developed to examine trapped electron trajectories during geomagnetic storms with the assumption of conservation of the first and second adiabatic invariants. The March 2013 storm was selected as an example because the geomagnetic activity Kp index sharply increased from 2 + to 7− at 6:00 UT on 17 March. Electron measurements with energies between 37 and 460 keV from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard Van Allen Probes (VAP) are used as initial conditions prior to the storm onset and served to validate test particle simulations during the storm. Simulation results help to interpret the observed electron injection as nondiffusive radial transport over a short distance in the inner belt and slot. . .
Date: 08/2016 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA022881 Available at: http://doi.wiley.com/10.1002/2016JA022881
More Details
Authors: Nosé M., Oimatsu S., Keika K, Kletzing C A, Kurth W S, et al.
Title: Formation of the oxygen torus in the inner magnetosphere: Van Allen Probes observations
Abstract: We study the formation process of an oxygen torus during the 12–15 November 2012 magnetic storm, using the magnetic field and plasma wave data obtained by Van Allen Probes. We estimate the local plasma mass density (ρL) and the local electron number density (neL) from the resonant frequencies of standing Alfvén waves and the upper hybrid resonance band. The average ion mass (M) can be calculated by M ∼ ρL/neL under the assumption of quasi-neutrality of plasma. During the storm recovery phase, both Probe A and Probe B observe the oxygen torus at L = 3.0–4.0 and L = 3.7–4.5, respectively, on the morning side. The oxygen torus has M = 4.5–8 amu and extends around the plasmapause that is identified at L∼3.2–3.9. We find that during the initial phase, M is 4–7 amu throughout . . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020593 Available at: http://doi.wiley.com/10.1002/2014JA020593
More Details
Authors: Omura Yoshiharu, Miyashita Yu, Yoshikawa Masato, Summers Danny, Hikishima Mitsuru, et al.
Title: Formation process of relativistic electron flux through interaction with chorus emissions in the Earth's inner magnetosphere
Abstract: We perform test particle simulations of energetic electrons interacting with whistler mode chorus emissions. We compute trajectories of a large number of electrons forming a delta function with the same energy and equatorial pitch angle. The electrons are launched at different locations along the magnetic field line and different timings with respect to a pair of chorus emissions generated at the magnetic equator. We follow the evolution of the delta function and obtain a distribution function in energy and equatorial pitch angle, which is a numerical Green's function for one cycle of chorus wave-particle interaction. We obtain the Green's functions for the energy range 10 keV–6 MeV and all pitch angles greater than the loss cone angle. By taking the convolution integral of the Green's f. . .
Date: 11/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 9545–9562 DOI: 10.1002/2015JA021563 Available at: http://doi.wiley.com/10.1002/2015JA021563http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021563
More Details
G
Authors: Ganguli G., Tejero E., Crabtree C., Amatucci W., and Rudakov L.
Title: Generation of electromagnetic waves in the very low frequency band by velocity gradient
Abstract: It is shown that a magnetized plasma layer with a velocity gradient in the flow perpendicular to the ambient magnetic field is unstable to waves in the Very Low Frequency band that spans the ion and electron gyrofrequencies. The waves are formally electromagnetic. However, depending on wave vector k⎯⎯=kc/ωpe (normalized by the electron skin depth) and the obliqueness, k⊥/k|| , where k⊥,∣∣∣∣ are wave vectors perpendicular and parallel to the magnetic field, the waves are closer to electrostatic in nature when k⎯⎯≫1 and k⊥≫k|| and electromagnetic otherwise. Inhomogeneous transverse flows are generated in plasma that contains a static electric field perpendicular to the magnetic field, a configuration that may naturally arise in the boundary layer between plasmas of. . .
Date: 01/2014 Publisher: Physics of Plasmas Pages: 012107 DOI: 10.1063/1.4862032 Available at: http://scitation.aip.org/content/aip/journal/pop/21/1/10.1063/1.4862032
More Details
Authors: Lessard Marc R., Paulson Kristoff, Spence Harlan E., Weaver Carol, Engebretson Mark J, et al.
Title: Generation of EMIC Waves and Effects on Particle Precipitation During a Solar Wind Pressure Intensification with B z >
Abstract: During geomagnetic storms, some fraction of the solar wind energy is coupled via reconnection at the dayside magnetopause, a process that requires a southward interplanetary magnetic field Bz. Through a complex sequence of events, some of this energy ultimately drives the generation of electromagnetic ion cyclotron (EMIC) waves, which can then scatter energetic electrons and ions from the radiation belts. In the event described in this paper, the interplanetary magnetic field remained northward throughout the event, a condition unfavorable for solar wind energy coupling through low‐latitude reconnection. While this resulted in SYM/H remaining positive throughout the event (so this may not be considered a storm, in spite of the very high solar wind densities), pressure fluctuations were d. . .
Date: 05/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2019JA026477 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JA026477
More Details
Authors: Gamayunov Konstantin V., Min Kyungguk, Saikin Anthony A., and Rassoul Hamid
Title: Generation of EMIC Waves Observed by Van Allen Probes at Low L Shells
Abstract: Observation of linearly polarized He+‐band electromagnetic ion cyclotron (EMIC) waves at low L shells is a new, and quite unexpected, result from the Van Allen Probes mission. Here we analyze the two EMIC wave events observed by Van Allen Probes at low L shells and put forward a new‐generation mechanism for the low‐L EMIC waves. Both events were observed at L ∼ 3 but one of them has a discrete spectrum near the O+ gyrofrequency and its second harmonic, whereas the second event has a broad spectrum between the O+ gyrofrequency and its second harmonic. For both events, the major conclusions of our analysis can be summarized as follows. (1) Only O+ causes EMIC wave generation, and instability is driven by the positive derivatives of distribution functions over perpendicular component . . .
Date: 10/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025629 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025629
More Details
Authors: Xiao Fuliang, Liu Si, Tao Xin, Su Zhenpeng, Zhou Qinghua, et al.
Title: Generation of extremely low frequency chorus in Van Allen radiation belts
Abstract: Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency fce, was generated by energetic electrons originating from Earth's plasma sheet. Chorus below 0.1 fce has seldom been reported until the recent data from Van Allen Probes, but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency, relativistic effects should be considered in the formula for whistler mode wave growth rate. Here we report high-resolution observations during the 14 October 2014 small storm and firstly demonstrate, using a fully relativistic simulation, that electrons with the high-energy tail p. . .
Date: 03/2017 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2016JA023561 Available at: http://doi.wiley.com/10.1002/2016JA023561
More Details
Authors: Fu Xiangrong, Gary Peter, Reeves Geoffrey D, Winske Dan, and Woodroffe Jesse R.
Title: Generation of Highly Oblique Lower-band Chorus via Nonlinear Three-wave Resonance
Abstract: Chorus in the inner magnetosphere has been observed frequently at geomagnetically active times, typically exhibiting a two-band structure with a quasi-parallel lower-band and an upper-band with a broad range of wave normal angles. But recent observations by Van Allen Probes confirm another type of lower-band chorus, which has a large wave normal angle close to the resonance cone angle. It has been proposed that these waves could be generated by a low-energy beam-like electron component or by temperature anisotropy of keV electrons in the presence of a low-energy plateau-like electron component. This paper, however, presents an alternative mechanism for generation of this highly oblique lower-band chorus. Through a nonlinear three-wave resonance, a quasi-parallel lower-band chorus wave can . . .
Date: 09/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL074411 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017GL074411/full
More Details
Authors: Zhou Qinghua, Xiao Fuliang, Yang Chang, Liu Si, He Yihua, et al.
Title: Generation of lower and upper bands of electrostatic electron cyclotron harmonic waves in the Van Allen radiation belts
Abstract: Electrostatic electron cyclotron harmonic (ECH) waves generated by the electron loss cone distribution can produce efficient scattering loss of plasma sheet electrons, which has a significant effect on the dynamics in the outer magnetosphere. Here we report two ECH emission events around the same location L≈ 5.7–5.8, MLT ≈ 12 from Van Allen Probes on 11 February (event A) and 9 January 2014 (event B), respectively. The spectrum of ECH waves was centered at the lower half of the harmonic bands during event A, but the upper half during event B. The observed electron phase space density in both events is fitted by the subtracted bi-Maxwellian distribution, and the fitting functions are used to evaluate the local growth rates of ECH waves based on a linear theory for homogeneous plasmas.. . .
Date: 05/2017 Publisher: Geophysical Research Letters DOI: 10.1002/2017GL073051 Available at: http://onlinelibrary.wiley.com/doi/10.1002/2017GL073051/full
More Details
Authors: He Yihua, Xiao Fuliang, Su Zhenpeng, Zheng Huinan, Yang Chang, et al.
Title: Generation of lower L -shell dayside chorus by energetic electrons from the plasmasheet
Abstract: Currently, the generation mechanism for the lower L‐shell dayside chorus has still remained an open question. Here, we report two storm events: 06‐07 March 2016 and 20‐21 January 2016, when Van Allen Probes observed enhanced dayside chorus with lower and higher wave normal angles (the angles between the wave vector and the geomagnetic field) in the region of L = 3.5‐6.3 and MLT = 5.6‐13.5. Hot and energetic (∼ 1‐100 keV) electrons displayed enhancements in fluxes and anisotropy when they were injected from the plasmasheet and drifted from midnight through dawn toward the dayside. Calculations of chorus local growth rates under different waves normal angles show that the upper cutoff and peak wave frequencies display similar patterns to the observations. Chorus growth rates ma. . .
Date: 09/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2017JA024889 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2017JA024889
More Details
Authors: Agapitov O. V., Krasnoselskikh V., Mozer F S, Artemyev A. V., and Volokitin A. S.
Title: Generation of nonlinear Electric Field Bursts in the outer radiation belt through the parametric decay of whistler waves
Abstract: Huge numbers of different non-linear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on the Van Allen Probes. Some of them are associated with whistler waves. Such TDS often emerge on the forward edges of the whistler wave packets and form chains. The parametric decay of a whistler wave into a whistler wave propagating in the opposite direction and an electron acoustic wave is studied experimentally as well as analytically, using Van Allen Probes data. The resulting electron acoustic wave is considered to be the source of electron scale TDS. The measured parameters of the three waves (two whistlers and the electron acoustic wave) are in a good agreement with an assumption . . .
Date: 05/2015 Publisher: Geophysical Research Letters DOI: 10.1002/2015GL064145 Available at: http://doi.wiley.com/10.1002/2015GL064145
More Details
Authors: Chen Lunjin, Thorne Richard M, Bortnik Jacob, Li Wen, Horne Richard B, et al.
Title: Generation of Unusually Low Frequency Plasmaspheric Hiss
Abstract: It has been reported from Van Allen Probe observations that plasmaspheric hiss intensification in the outer plasmasphere, associated with a substorm injection on Sept 30 2012, occurred with a peak frequency near 100 Hz, well below the typical plasmaspheric hiss frequency range, extending down to ~20 Hz. We examine this event of unusually low frequency plasmaspheric hiss to understand its generation mechanism. Quantitative analysis is performed by simulating wave ray paths via the HOTRAY ray tracing code with measured plasma density and calculating ray path-integrated wave gain evaluated using the measured energetic electron distribution. We demonstrate that the growth rate due to substorm injected electrons is positive but rather weak, leading to small wave gain (~10 dB) during a sin. . .
Date: 08/2014 Publisher: Geophysical Research Letters DOI: 10.1002/2014GL060628 Available at: http://doi.wiley.com/10.1002/2014GL060628
More Details
Authors: Kubota Yuko, Omura Yoshiharu, Kletzing Craig, and Reeves Geoff
Title: Generation process of large-amplitude upper band chorus emissions observed by Van Allen Probes
Abstract: We analyze large‐amplitude upper‐band chorus emissions measured near the magnetic equator by the EMFISIS (Electric and Magnetic Field Instrument Suite and Integrated Science) instrument package onboard the Van Allen Probes. In setting up the parameters of source electrons exciting the emissions based on theoretical analyses and observational results measured by the HOPE (Helium Oxygen Proton Electron) instrument, we calculate threshold and optimum amplitudes with the nonlinear wave growth theory. We find that the optimum amplitude is larger than the threshold amplitude obtained in the frequency range of the chorus emissions and that the wave amplitudes grow between the threshold and optimum amplitudes. In the frame of the wave growth process, the nonlinear growth rates are much greater. . .
Date: 04/2018 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2017JA024782 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2017JA024782
More Details
Authors: Reeves G. D., and Daglis I. A.
Title: Geospace Magnetic Storms and the Van Allen Radiation Belts
Abstract: N/A
Date: Publisher: Oxford University Press DOI: N/A
More Details
Authors: Motoba Tetsuo, Takahashi Kazue, Rodriguez Juan V., and Russell Christopher T.
Title: Giant pulsations on the afternoonside: Geostationary satellite and ground observations
Abstract: Giant pulsations (Pgs) are a special class of oscillations recognized in ground magnetometer records as exhibiting highly regular sinusoidal waveforms in the east-west component with periods around 100s. Previous statistical studies showed that Pgs occur almost exclusively on the morningside with peak occurrence in the postmidnight sector. In this paper, we present observations of Pgs extending to the afternoonside, using data from the GOES13 and 15 geostationary satellites and multiple ground magnetometers located in North America. For a long-lasting event on 29 February 2012, which spanned ∼08–18h magnetic local time, we show that basic Pg properties did not change with the local time, although the period of the pulsations was longer at later local time due to increasing mass loading. . .
Date: 10/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: 8350 - 8367 DOI: 10.1002/2015JA021592 Available at: http://doi.wiley.com/10.1002/2015JA021592http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021592
More Details
Authors: Shprits Y Y, and Spasojevic M.
Title: Global and comprehensive analysis of the inner magnetosphere as a coupled system: Physical understanding and applications
Abstract: The third Inner Magnetosphere Coupling (IMC III) workshop was held March 2015 at University of California, Los Angeles. The workshop included extensive discussion of space weather and applications bring together scientists from the solar wind, magnetosphere and ionospheric communities as well as space weather stakeholders and researchers focusing on translational research and applications in industry.
Date: 08/2015 Publisher: Space Weather DOI: 10.1002/2015SW001295 Available at: http://doi.wiley.com/10.1002/2015SW001295http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015SW001295
More Details
Authors: Hwang K.-J., Sibeck D G, Fok M.-C. H., Zheng Y., Nishimura Y., et al.
Title: The global context of the 14 November, 2012 storm event
Abstract: From 2 to 5 UT on 14 November, 2012, the Van Allen Probes observed repeated particle flux dropouts during the main phase of a geomagnetic storm as the satellites traversed the post-midnight to dawnside inner magnetosphere. Each flux dropout corresponded to an abrupt change in the magnetic topology, i.e., from a more dipolar configuration to a configuration with magnetic field lines stretched in the dawn-dusk direction. Geosynchronous GOES spacecraft located in the dusk and near-midnight sectors and the LANL constellation with wide local time coverage also observed repeated flux dropouts and stretched field lines with similar occurrence patterns to those of the Van Allen Probe events. THEMIS recorded multiple transient abrupt expansions of the evening-side magnetopause ~20–30 min prior to. . .
Date: 02/2015 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2014JA020826 Available at: http://doi.wiley.com/10.1002/2014JA020826
More Details
Authors: Min Kyungguk, Lee Jeongwoo, Keika Kunihiro, and Li W
Title: Global distribution of EMIC waves derived from THEMIS observations
Abstract: [1] Electromagnetic ion cyclotron (EMIC) waves play an important role in magnetospheric dynamics and their global distribution has been of great interest. This paper presents the distribution of EMIC waves over a broader range than ever before, as enabled by observations with the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft from 2007 to 2010. Our major findings are: (1) There are two major peaks in the EMIC wave occurrence probability. One is at dusk and 8–12 RE where the helium band dominates the hydrogen band waves. The other is at dawn and 10–12 RE where the hydrogen band dominates the helium band waves. (2) In terms of wave spectral power the dusk events are stronger (≈10 nT2/Hz) than the dawn events (≈3 nT2/Hz). (3) The dawn . . .
Date: 05/2012 Publisher: Journal of Geophysical Research DOI: 10.1029/2012JA017515
More Details
Authors: Yuan Zhigang, Ouyang Zhihai, Yu Xiongdong, Huang Shiyong, Yao Fei, et al.
Title: Global distribution of proton rings and associated magnetosonic wave instability in the inner magnetosphere
Abstract: Using the Van Allen Probe A observations, we obtained the global distribution of proton rings and calculated the linear wave growth rate of fast magnetosonic (MS) waves in the region L ~ 3‐6. Our statistical and calculated results demonstrate that MS waves can be locally excited on the dayside outside the plasmapause, as well as in the dusk sector inside the plasmapause. The frequency range of unstable MS waves is strongly modulated by the ratio of the proton ring velocity (Vr) to the local Alfvén speed (VA). High harmonic MS waves (ω>20ΩH+) can be excited outside the plasmapause where Vr/VA<1 while low harmonic MS waves (ω<10ΩH+) with frequencies less than ~30 Hz are found to be excited both outside and inside the plasmapause where 1Date: 09/2018 Publisher: Geophysical Research Letters DOI: 10.1029/2018GL079999 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL079999
More Details
Authors: Spasojevic M., Shprits Y.Y., and Orlova K.
Title: Global Empirical Models of Plasmaspheric Hiss using Van Allen Probes
Abstract: Plasmaspheric hiss is a whistler mode emission that permeates the Earth's plasmasphere and is a significant driver of energetic electron losses through cyclotron-resonant pitch angle scattering. The EMFISIS instrument on the Van Allen Probes mission provides vastly improved measurements of the hiss wave environment including continuous measurements of the wave magnetic field cross-spectral matrix and enhanced low frequency coverage. Here, we develop empirical models of hiss wave intensity using two years of Van Allen Probes data. First, we describe the construction of the hiss database. Then, we compare the hiss spectral distribution and integrated wave amplitude obtained from Van Allen Probes to those previously extracted from the CRRES mission. Next, we develop a cubic regression model o. . .
Date: 11/2015 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/2015JA021803 Available at: http://doi.wiley.com/10.1002/2015JA021803http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015JA021803
More Details
Authors: Stephens G. K., Sitnov M I, Korth H., Tsyganenko N A, Ohtani S, et al.
Title: Global Empirical Picture of Magnetospheric Substorms Inferred From Multimission Magnetometer Data
Abstract: Magnetospheric substorms represent key explosive processes in the interaction of the Earth's magnetosphere with the solar wind, and their understanding and modeling are critical for space weather forecasting. During substorms, the magnetic field on the nightside is first stretched in the antisunward direction and then it rapidly contracts earthward bringing hot plasmas from the distant space regions into the inner magnetosphere, where they contribute to geomagnetic storms and Joule dissipation in the polar ionosphere, causing impressive splashes of aurora. Here we show for the first time that mining millions of spaceborne magnetometer data records from multiple missions allows one to reconstruct the global 3‐D picture of these stretching and dipolarization processes. Stretching results i. . .
Date: 01/2019 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1029/2018JA025843 Available at: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018JA025843
More Details

Pages