Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature 2019 tech.scichina.com link.springer.com Upward propagation of lightning-generated whistler waves into the radiation belts
作者：
Guo, MingYue;Zhou, QingHua;Xiao, FuLiang* ;Liu, Si;He, YiHua;...
期刊：
中国科学:技术科学(英文版) ,2020年63(2):243-248 ISSN：1674-7321
通讯作者：
Xiao, FuLiang
作者机构：
[Xiao, FuLiang; Yang, Chang; Guo, MingYue; Liu, Si; He, YiHua; Zhou, QingHua] Changsha Univ Sci, Sch Phys, Elect Sciences, Technology, Changsha, Peoples R China.
通讯机构：
[Xiao, FuLiang] C;Changsha Univ Sci, Sch Phys, Elect Sciences, Technology, Changsha, Peoples R China.
关键词：
lightning-generated whistler waves;radiation belts;numerical simulation
摘要：
Lightning-generated whistler (LGW) waves which induce energetic electron precipitation provide an important coupling between the ionosphere and radiation belts. Using the ray-tracing technique, we examine the propagation behaviour of LGW waves and show that they can travel upward into the radiation belts during higher geomagnetic activities due to the plasmapause inward compression, particularly in cases of lower wave frequencies, lower wave normal angles and azimuthal angles. Both perpendicular and parallel group velocities of LGW waves remain in relatively small values inside the plasmasphere but change rapidly to high values outside the plasmasphere. The launching latitude increases with increasing LGW wave normal angle. These results here further reveal a detailed picture on how LGW waves escape out of the plasmasphere and onto the radiation belts.
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Generation of simultaneous H(+)and He(+)band EMIC waves in the nightside radiation belt
作者：
Guan ChunYi;Shang XiongJun;Xie YanQiong;Yang Chang;Zhang Sai;...
期刊：
中国科学:技术科学(英文版) ,2020年63(11):2369-2374 ISSN：1674-7321
通讯作者：
Liu Si;Xiao FuLiang
作者机构：
[Liu, S; Xiao, FL; Zhang Sai; Xiao FuLiang; Yang Chang; Liu Si; Shang XiongJun; Guan ChunYi] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Peoples R China.;[Xie YanQiong] Natl Univ Def Technol, Coll Meteorol & Oceanog, Nanjing 211101, Peoples R China.;[Guan ChunYi] Chinese Acad Sci, State Key Lab Space Weather, Beijing 100190, Peoples R China.
通讯机构：
[Liu, S; Xiao, FL] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410114, Peoples R China.
关键词：
EMIC waves instability;nightside radiation belt;Van Allen Probes;coordinated observations
摘要：
Previous studies have shown that EMIC waves occur preferentially in the afternoon sector of the magnetosphere. Here we report obliquely propagating H+ and He+ band EMIC waves detected by Van Allen Probe B in the region of MLT=22.7–23.5 during the June 20, 2013 substorm. Using the correlated energetic proton data, we present continuous calculations on EMIC wave growth rates along the inward orbit in the region L=5.5−4.2. The modeled growth rate shows remarkable agreement with the observed double band EMIC waves in both temporal and spatial evolutions. The current results demonstrate that H+ and He+ band EMIC waves can be simultaneously excited in the midnight sector under appropriate conditions. © 2020, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.
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Excitation of Highly Oblique Lower Band and Upper Band Chorus by a Loss Cone Feature and Temperature Anisotropy Distribution
作者：
Zhou, Qinghua;Yang, Chang;He, Yihua;Liu, Si;Gao, Zhonglei;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2019年46(4):1929-1936 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Gao, Zhonglei; Zhou, Qinghua; He, Yihua; Liu, Si] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Xiao, Fuliang; Zhou, Qinghua] Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.;[Xiao, Fuliang; Zhou, Qinghua] Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monito, Changsha, Hunan, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monito, Changsha, Hunan, Peoples R China.
关键词：
highly oblique chorus;wave-particle interaction;RBSP results;radiation belts
摘要：
Recent studies have indicated that highly oblique lower band chorus could be excited by temperature anisotropy with a low-energy electron plateau. Here we present another excitation mechanism of highly oblique lower and upper band chorus by using the simultaneous observations and numerical modeling. During 23:00–24:00UT on 3 July 2016, Van Allen probe A observed chorus with the wave normal angle close to the resonance cone both in the lower and upper bands around L=5.0 and MLT=3. Enhanced flux and pitch angle anisotropy of energetic electrons were observed in the same spatial region. Calculations of chorus growth rates show that highly oblique chorus waves can be excited by the energetic electrons with a loss cone feature and distinct temperature anisotropy, particularly more efficient in the presence of a low-energy plateau. The temperature anisotropy for the oblique upper band is higher than that for the lower band. ©2019. American Geophysical Union. All Rights Reserved.
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Global Occurrences of Electrostatic Electron Cyclotron Harmonic Waves Associated With Radiation Belt Electron Distributions
作者：
Chen, Yaru;Zhou, Qinghua;He, Yihua;Yang, Chang;Liu, Si;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2019年46(10):5028-5033 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Chen, Yaru; Xiao, Fuliang; Gao, Zhonglei; Zhou, Qinghua; He, Yihua; Liu, Si] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Chen, Yaru; Xiao, Fuliang; Zhou, Qinghua] Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.;[Chen, Yaru; Xiao, Fuliang; Zhou, Qinghua] Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monitor, Changsha, Hunan, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monitor, Changsha, Hunan, Peoples R China.
关键词：
Electrostatic electron cyclotron harmonic waves;electron ring distribution;global occurrences;radiation belt;Van Allen Probe observation
摘要：
<jats:title>Abstract</jats:title><jats:p>Electrostatic electron cyclotron harmonic (ECH) waves can yield diffuse aurora primarily at higher <jats:italic>L</jats:italic>‐shells by driving efficient precipitation loss of plasma sheet electrons. Here using the Van Allen Probes high resolution data, we examine in detail the global occurrences of ECH waves during the period from 1 October 2012 to 30 June 2017 and find that there are totally 419 events of enhanced ECH waves. The statistical results demonstrate that ECH waves can be present over a broad region of <jats:italic>L</jats:italic>=4–6 and 00–24MLT, with a higher occurrence in the region of <jats:italic>L</jats:italic>=5–6 and 06–19MLT. The electron phase space density exhibits a distinct ring distribution (<jats:italic>∂</jats:italic><jats:italic>f</jats:italic>/<jats:italic>∂</jats:italic><jats:italic>v</jats:italic><jats:sub>⊥</jats:sub> > 0) with the peak energy around a few kiloelectron volts. Both ECH wave events and the electron ring distributions are closely related and tend to be more distinct with increasing geomagnetic activity.</jats:p>
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Global Occurrences of Auroral Kilometric Radiation Related to Suprathermal Electrons in Radiation Belts
作者：
Zhao, Wanli;Liu, Si;Zhang, Sai;Zhou, Qinghua;Yang, Chang;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2019年46(13):7230-7236 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Zhao, Wanli; Yang, Chang; Zhang, Sai; Xiao, Fuliang; Gao, Zhonglei; Liu, Si; Zhou, Qinghua; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Zhao, Wanli; Xiao, Fuliang] Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monitor, Changsha, Hunan, Peoples R China.;[Zhao, Wanli; Xiao, Fuliang] Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Higher Educ Key Lab Modeling & Monitor, Changsha, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Hunan Prov Key Lab Flexible Elect Mat Genome Engn, Changsha, Hunan, Peoples R China.
关键词：
auroral kilometric radiation;suprathermal electron flux enhancements;global occurrence;radiation belt
摘要：
Auroral kilometric radiation (AKR) can potentially produce serious damage to space-borne systems by accelerating trapped radiation belt electrons to relativistic energies. Here we examine the global occurrences of AKR emissions in radiation belts based on Van Allen Probes observations from 1 October 2012 to 31 December 2016. The statistical results (1,848 events in total) show that AKR covers a broad region of L=3–6.5 and 00–24 magnetic local time (MLT), with a higher occurrence on the nightside (20–24 MLT and 00–04 MLT) within L=5–6.5. All the AKR events are observed to be accompanied with suprathermal (∼1keV) electron flux enhancements. During active geomagnetic periods, both AKR occurrences and electron injections tend to be more distinct, and AKR emission extends to the dayside. The current study shows that AKR emissions from the remote sources are closely associated with electron injections. © 2019. American Geophysical Union. All Rights Reserved.
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Quantifying Extremely Rapid Flux Enhancements of Radiation Belt Relativistic Electrons Associated With Radial Diffusion
作者：
Liu, Si;Yan, Qi;Yang, Chang;Zhou, Qinghua;He, Zhaoguo;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2018年45(3):1262-1270 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Gao, Zhonglei; Liu, Si; Zhou, Qinghua; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Liu, Si; He, Zhaoguo] Univ Texas Dallas, Dept Phys, William B Hanson Ctr Space Sci, Richardson, TX 75083 USA.;[Yan, Qi] Macau Univ Sci & Technol, Lunar & Planetary Sci Lab, Macau, Peoples R China.;[He, Zhaoguo] Harbin Inst Technol, Shenzhen Grad Sch, Shenzhen, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
radial diffusion;chorus-driven acceleration;radiation belt;Van Allen Probes;THEMIS
摘要：
Previous studies have revealed a typical picture that seed electrons are transported inward under the drive of radial diffusion and then accelerated via chorus to relativistic energies. Here we show a potentially different process during the 2–3 October 2013 storm when Van Allen Probes observed extremely rapid (by about 50 times in 2h) flux enhancements of relativistic (1.8–3.4MeV) electrons but without distinct chorus at lower L-shells. Meanwhile, Time History of Events and Macroscale Interactions during Substorms satellites simultaneously measured enhanced chorus and fluxes of energetic (∼100–300keV) seed electrons at higher L-shells. Numerical calculations show that chorus can efficiently accelerate seed electrons at L ∼ 8.3. Then radial diffusion further increased the phase space density of relativistic electrons throughout the outer radiation belts, with a remarkable agreement with the observation in magnitude and timescale. The current results provide a different physical scenario on the interplay between radial diffusion and local acceleration in outer radiation belt. ©2018. American Geophysical Union. All Rights Reserved.
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Nonlinear Coupling Between Whistler-Mode Chorus and Electron Cyclotron Harmonic Waves in the Magnetosphere
作者：
Gao, Zhonglei;Su, Zhenpeng* ;Xiao, Fuliang;Summers, Danny;Liu, Nigang;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2018年45(23):12,685-12,693 ISSN：0094-8276
通讯作者：
Su, Zhenpeng
作者机构：
[Gao, Zhonglei; Wei, Fengsi] Harbin Inst Technol, Inst Space Sci & Appl Technol, Shenzhen, Peoples R China.;[Xiao, Fuliang; Gao, Zhonglei] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Su, Zhenpeng; Liu, Nigang; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China.;[Su, Zhenpeng; Liu, Nigang; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Anhui, Peoples R China.;[Su, Zhenpeng; Liu, Nigang; Zheng, Huinan; Wang, Yuming; Wang, Shui] CAS Ctr Excellence Comparat Planetol, Hefei, Anhui, Peoples R China.
通讯机构：
[Su, Zhenpeng] U;[Su, Zhenpeng] C;Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China.;Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Anhui, Peoples R China.;CAS Ctr Excellence Comparat Planetol, Hefei, Anhui, Peoples R China.
关键词：
aurora;chorus wave;electron cyclotron harmonic wave;nonlinear wave-wave interaction;radiation belt
摘要：
Electromagnetic whistler-mode chorus and electrostatic electron cyclotron harmonic (ECH) waves can contribute significantly to auroral electron precipitation and radiation belt electron acceleration. In the past, linear and nonlinear wave-particle interactions have been proposed to explain the occurrences of these magnetospheric waves. By analyzing Van Allen Probes data, we present here the first evidence for nonlinear coupling between chorus and ECH waves. The sum-frequency and difference-frequency interactions produced the ECH sidebands with discrete frequency sweeping structures exactly corresponding to the chorus rising tones. The newly generated weak sidebands did not satisfy the original electrostatic wave dispersion relation. After the generation of chorus and normal ECH waves by hot electron instabilities, the nonlinear wave-wave interactions could additionally redistribute energy among the resonant waves, potentially affecting to some extent the magnetospheric electron dynamics. ©2018. American Geophysical Union. All Rights Reserved.
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Exohiss wave enhancement following substorm electron injection in the dayside magnetosphere
作者：
ZhongLei Gao;ZhenPeng Su* ;FuLiang Xiao;HuiNan Zheng;YuMing Wang;...
期刊：
地球与行星物理(英文) ,2018年2(5):359-370 ISSN：2096-3955
通讯作者：
ZhenPeng Su
作者机构：
[YuMing Wang; Shui Wang] CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China;[D. N. Baker] Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Colorado, USA;[H.O. Funsten] ISR Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA;[J. B. Blake] The Aerospace Corporation, Los Angeles, California, USA;Collaborative Innovation Center of Astronautical Science and Technology, University of Science and Technology of China, Hefei 230026, China
通讯机构：
[ZhenPeng Su] C;CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China<&wdkj&>Collaborative Innovation Center of Astronautical Science and Technology, University of Science and Technology of China, Hefei 230026, China
关键词：
exohiss;radiation belt;substorm injection;whistler-mode instability
摘要：
Exohiss is a low-frequency structureless whistler-mode emission potentially contributing to the precipitation loss of radiation belt electrons outside the plasmasphere. Exohiss is usually considered the plasmaspheric hiss leaked out of the dayside plasmapause. However, the evolution of exohiss after the leakage has not been fully understood. Here we report the prompt enhancements of exohiss waves following substorm injections observed by Van Allen Probes. Within several minutes, the energetic electron fluxes around 100 keV were enhanced by up to 5 times, accompanied by an up to 10-time increase of the exohiss wave power. These substorm-injected electrons are shown to produce a new peak of linear growth rate in the exohiss band (< 0.1fce). The corresponding path-integrated growth rate of wave power within 10° latitude of the magnetic equatorial plane can reach 13.4, approximately explaining the observed enhancement of exohiss waves. These observations and simulations suggest that the substorm-injected energetic electrons could amplify the preexisting exohiss waves. © 2018 by Earth and Planetary Physics
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Generation of Lower L Shell Dayside Chorus by Energetic Electrons From the Plasma Sheet
作者：
He, Yihua* ;Xiao, Fuliang* ;Su, Zhenpeng;Zheng, Huinan;Yang, Chang;...
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS ,2018年123(10):8109-8121 ISSN：2169-9380
通讯作者：
He, Yihua;Xiao, Fuliang
作者机构：
[Su, Zhenpeng; Zheng, Huinan; He, Yihua] Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China.;[Yang, Chang; Xiao, Fuliang; He, Yihua; Liu, Si; Zhou, Qinghua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Su, Zhenpeng; Zheng, Huinan; He, Yihua] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Anhui, Peoples R China.;[He, Yihua] Univ Sci & Technol China, Sch Earth & Space Sci, Mengcheng Natl Geophys Observ, Hefei, Anhui, Peoples R China.
通讯机构：
[He, Yihua] U;[He, YH; Xiao, FL] C;Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China.;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Anhui, Peoples R China.
关键词：
Van Allen Probes;dayside chorus generation;radiation belt;wave-particle interaction
摘要：
Currently, the generation mechanism for the lower L shell dayside chorus has still remained an open question. Here we report two storm events: 6–7 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 plasma sheet 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 maximize for the parallel propagation and drop with increasing wave normal angles. The current results confirm that the observed lower L shell dayside chorus can be excited by anisotropic electrons originating from the plasma sheet in drifting from the nightside to the dayside.
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Storm Time Evolution of Outer Radiation Belt Relativistic Electrons by a Nearly Continuous Distribution of Chorus
作者：
Yang, Chang;Xiao, Fuliang* ;He, Yihua;Liu, Si;Zhou, Qinghua;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2018年45(5):2159-2167 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Zhao, Wanli; Yang, Chang; Xiao, Fuliang; He, Yihua; Liu, Si; Zhou, Qinghua; Guo, Mingyue] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Yang, Chang; He, Yihua] Univ Sci & Technol China, Dept Geophys & Planetary Sci, Hefei, Anhui, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
outer radiation belt;whistler mode chorus wave;energetic electron;wave-particle interaction;geomagnetic storm
摘要：
During the 13–14 November 2012 storm, Van Allen Probe A simultaneously observed a 10 h period of enhanced chorus (including quasi-parallel and oblique propagation components) and relativistic electron fluxes over a broad range of L = 3–6 and magnetic local time = 2–10 within a complete orbit cycle. By adopting a Gaussian fit to the observed wave spectra, we obtain the wave parameters and calculate the bounce-averaged diffusion coefficients. We solve the Fokker-Planck diffusion equation to simulate flux evolutions of relativistic (1.8–4.2 MeV) electrons during two intervals when Probe A passed the location L = 4.3 along its orbit. The simulating results show that chorus with combined quasi-parallel and oblique components can produce a more pronounced flux enhancement in the pitch angle range ∼45°–80°, consistent well with the observation. The current results provide the first evidence on how relativistic electron fluxes vary under the drive of almost continuously distributed chorus with both quasi-parallel and oblique components within a complete orbit of Van Allen Probe.<br/> ©2018. American Geophysical Union. All Rights Reserved.
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A positive correlation between energetic electron butterfly distributions and magnetosonic waves in the radiation belt slot region
作者：
Yang, Chang;Su, Zhenpeng* ;Xiao, Fuliang;Zheng, Huinan;Wang, Yuming;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2017年44(9):3980-3990 ISSN：0094-8276
通讯作者：
Su, Zhenpeng
作者机构：
[Su, Zhenpeng; Yang, Chang; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Dept Geophys & Planetary Sci, Hefei, Peoples R China.;[Yang, Chang; Xiao, Fuliang] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Peoples R China.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.;[Reeves, G. D.] Los Alamos Natl Lab, Space Sci & Applicat Grp, Los Alamos, NM USA.
通讯机构：
[Su, Zhenpeng] U;Univ Sci & Technol China, Dept Geophys & Planetary Sci, Hefei, Peoples R China.;Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Peoples R China.
关键词：
radiation belt;butterfly distributions;wave-particle interaction;magnetosonic wave;Landau resonance;electron acceleration
摘要：
Energetic (hundreds of keV) electrons in the radiation belt slot region have been found to exhibit the butterfly pitch angle distributions. Resonant interactions with magnetosonic and whistler-mode waves are two potential mechanisms for the formation of these peculiar distributions. Here we perform a statistical study of energetic electron pitch angle distribution characteristics measured by Van Allen Probes in the slot region during a 3year period from May 2013 to May 2016. Our results show that electron butterfly distributions are closely related to magnetosonic waves rather than to whistler-mode waves. Both electron butterfly distributions and magnetosonic waves occur more frequently at the geomagnetically active times than at the quiet times. In a statistical sense, more distinct butterfly distributions usually correspond to magnetosonic waves with larger amplitudes and vice versa. The averaged magnetosonic wave amplitude is less than 5pT in the case of normal and flat-top distributions with a butterfly index BI =1 but reaches ∼50–95pT in the case of distinct butterfly distributions with BI >1.3. For magnetosonic waves with amplitudes >50pT, the occurrence rate of butterfly distribution is above 80%. Our study suggests that energetic electron butterfly distributions in the slot region are primarily caused by magnetosonic waves. ©2017. American Geophysical Union. All Rights Reserved.
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Generation of extremely low frequency chorus in Van Allen radiation belts
作者：
Xiao, Fuliang* ;Liu, Si;Tao, Xin;Su, Zhenpeng;Zhou, Qinghua;...
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS ,2017年122(3):3201-3211 ISSN：2169-9380
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Liu, Si; He, Yihua; Xiao, Fuliang; Zhou, Qinghua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Tao, Xin; Su, Zhenpeng; Gao, Zhonglei] Univ Sci & Technol China, Chinese Acad Sci, Key Lab Basic Plasma Phys, Hefei, Peoples R China.;[He, Zhaoguo] Harbin Inst Technol, Shenzhen Grad Sch, Shenzhen, Peoples R China.;[Baker, D. N.] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
ELF chorus waves;wave-particle interaction;relativistic distribution;RBSP results
摘要：
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 population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 fce. The simulated wave growth displays a very similar pattern to the observations. The current results can be applied to Jupiter, Saturn, and other magnetized planets.
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Generation of lower and upper bands of electrostatic electron cyclotron harmonic waves in the Van Allen radiation belts
作者：
Zhou, Qinghua;Xiao, Fuliang* ;Yang, Chang;Liu, Si;He, Yihua;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2017年44(11):5251-5258 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Zhou, Qinghua; Liu, Si; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Baker, D. N.] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.;[Reeves, G. D.] Los Alamos Natl Lab, Space Sci & Applicat Grp, Los Alamos, NM USA.;[Funsten, H. O.] Los Alamos Natl Lab, ISR Div, Los Alamos, NM USA.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
ECH waves;wave-particle interaction;RBSP results
摘要：
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. ECH waves are excited by the loss cone instability of 50 eV–1 keV electrons in the lower half of harmonic bands in the low-density plasmasphere in event A, and 1–10 keV electrons in the upper half of harmonic bands in a relatively high-density region in event B. The current results successfully explain observations and provide a first direct evidence on how ECH waves are generated in the lower and upper half of harmonic frequency bands.
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Intense low-frequency chorus waves observed by Van Allen Probes: Fine structures and potential effect on radiation belt electrons
作者：
Gao, Zhonglei;Su, Zhenpeng* ;Zhu, Hui;Xiao, Fuliang;Zheng, Huinan;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2016年43(3):967-977 ISSN：0094-8276
通讯作者：
Su, Zhenpeng
作者机构：
[Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Zhu, Hui; Wang, Shui; Gao, Zhonglei] Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China.;[Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Zhu, Hui; Wang, Shui; Gao, Zhonglei] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei 230026, Peoples R China.;[Zhu, Hui; Gao, Zhonglei] Univ Sci & Technol China, Sch Earth & Space Sci, Mengcheng Natl Geophys Observ, Hefei 230026, Peoples R China.;[Xiao, Fuliang] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Shen, Chao] Harbin Inst Technol, Shenzhen Grad Sch, Shenzhen, Peoples R China.
通讯机构：
[Su, Zhenpeng] U;Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Peoples R China.;Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei 230026, Peoples R China.
关键词：
low-frequency chorus;rising tones;hiss-like band;cyclotron resonance;radiation belt;Van Allen Probes
摘要：
Frequency distribution is a vital factor in determining the contribution of whistler mode chorus to radiation belt electron dynamics. Chorus is usually considered to occur in the frequency range 0.1-0.8fce-eq (with the equatorial electron gyrofrequency fce-eq). We here report an event of intense low-frequency chorus with nearly half of wave power distributed below 0.1fce-eq observed by Van Allen Probe A on 27 August 2014. This emission propagated quasi-parallel to the magnetic field and exhibited hiss-like signatures most of the time. The low-frequency chorus can produce the rapid loss of low-energy (∼0.1 MeV) electrons, different from the normal chorus. For high-energy (≥0.5 MeV) electrons, the low-frequency chorus can yield comparable momentum diffusion to that of the normal chorus but much stronger (up to 2 orders of magnitude) pitch angle diffusion near the loss cone. © 2016. American Geophysical Union. All Rights Reserved.
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Evolution of chorus emissions into plasmaspheric hiss observed by Van Allen Probes
作者：
Zhou, Qinghua;Xiao, Fuliang* ;Yang, Chang;Liu, Si;He, Yihua;...
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS ,2016年121(5):4518-4529 ISSN：2169-9380
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Zhou, Qinghua; Liu, Si; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Wygant, J. R.] Univ Minnesota, Sch Phys & Astron, Minneapolis, MN USA.;[Baker, D. N.] Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO USA.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.;[Reeves, G. D.] Los Alamos Natl Lab, Space Sci & Applicat Grp, Los Alamos, NM USA.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
plasmaspheric hiss;chorus waves;RBSP results
摘要：
The two classes of whistler mode waves (chorus and hiss) play different roles in the dynamics of radiation belt energetic electrons. Chorus can efficiently accelerate energetic electrons, and hiss is responsible for the loss of energetic electrons. Previous studies have proposed that chorus is the source of plasmaspheric hiss, but this still requires an observational confirmation because the previously observed chorus and hiss emissions were not in the same frequency range in the same time. Here we report simultaneous observations form Van Allen Probes that chorus and hiss emissions occurred in the same range ∼300–1500Hz with the peak wave power density about 10−5nT2/Hz during a weak storm on 3 July 2014. Chorus emissions propagate in a broad region outside the plasmapause. Meanwhile, hiss emissions are confined inside the plasmasphere, with a higher intensity and a broader area at a lower frequency. A sum of bi-Maxwellian distribution is used to model the observed anisotropic electron distributions and to evaluate the instability of waves. A three-dimensional ray tracing simulation shows that a portion of chorus emission outside the plasmasphere can propagate into the plasmasphere and evolve into plasmaspheric hiss. Moreover, hiss waves below 1kHz are more intense and propagate over a broader area than those above 1kHz, consistent with the observation. The current results can explain distributions of the observed hiss emission and provide a further support for the mechanism of evolution of chorus into hiss emissions. ©2016. American Geophysical Union. All Rights Reserved.
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英文
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Explaining occurrences of auroral kilometric radiation in Van Allen radiation belts
作者：
Xiao, Fuliang* ;Zhou, Qinghua;Su, Zhenpeng;He, Zhaoguo;Yang, Chang;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2016年43(23):11,971-11,978 ISSN：0094-8276
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Zhou, Qinghua; Liu, Si; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Su, Zhenpeng; Gao, Zhonglei] Univ Sci & Technol China, Chinese Acad Sci, Key Lab Basic Plasma Phys, Hefei, Peoples R China.;[He, Zhaoguo] Shenzhen Grad Sch, Harbin Inst Technol, Shenzhen, Peoples R China.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.
关键词：
AKR emissions;ray tracing simulations;radiation belts;geomagnetic storms;satellite data
摘要：
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's spatial distribution and frequency range, and the current results have a wide application to all other magnetized astrophysical objects in the universe. ©2016. American Geophysical Union. All Rights Reserved.
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英文
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Magnetospheric chorus wave instability induced by relativistic Kappa-type distributions
作者：
Yang QiWu;Yang Chang;He YiHua;Liu Si;Zhou QingHua;...
期刊：
中国科学:技术科学(英文版) ,2016年59(11):1739-1745 ISSN：1674-7321
通讯作者：
Xiao FuLiang
作者机构：
[Xiao FuLiang; Yang QiWu; Yang Chang; Liu Si; Zhou QingHua; He YiHua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410004, Hunan, Peoples R China.
通讯机构：
[Xiao FuLiang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410004, Hunan, Peoples R China.
关键词：
Kappa-type distribution;energetic electrons;wave-particle interaction;chorus wave instability
摘要：
We study the field-aligned propagating magnetospheric chorus wave instability using a fully relativistic wave growth formula, the previously developed relativistic Kappa-type (KT) distribution and the regular Kappa distribution of energetic electrons. We demonstrate that the peak growth rate using the nonrelativistic Kappa simulation is higher than that using either the relativistic KT or the Kappa simulation at/above 100 keV, because the significant relativistic effect yields a reduction in the relativistic anisotropy. The relativistic anisotropy A_(rel) basically decreases as the thermal parameter θ~2 increases, allowing the peak growth by relativistic KT or Kappa distribution to stay at the lower frequency region. The growth rates tend to increase with the loss-cone parameter l because the overall anisotropy increases. Moreover, at high energy ~1.0 MeV, both the growth rate and the upper cutoff frequency become smaller as l increases for the relativistic KT calculation because the significant relativistic effect reduces both the resonant anisotropy and the number of the hot electrons, which is in contrast to the relativistic and nonrelativistic Kappa distribution calculations because the less relativistic or non-relativistic effect enhances the resonant anisotropy as l increases. The above results can be applied to the whistler-mode wave instability in the outer radiation belts of the Earth, the Jovian inner magnetosphere and other astrophysical plasmas where relativistic electrons often exist.
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英文
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Rapid flattening of butterfly pitch angle distributions of radiation belt electrons by whistler-mode chorus
作者：
Yang, Chang;Su, Zhenpeng* ;Xiao, Fuliang;Zheng, Huinan;Wang, Yuming;...
期刊：
GEOPHYSICAL RESEARCH LETTERS ,2016年43(16):8339-8347 ISSN：0094-8276
通讯作者：
Su, Zhenpeng
作者机构：
[Su, Zhenpeng; Yang, Chang; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Dept Geophys & Planetary Sci, Hefei, Peoples R China.;[Su, Zhenpeng; Yang, Chang; Zheng, Huinan; Wang, Yuming; Wang, Shui] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Peoples R China.;[Yang, Chang; Xiao, Fuliang] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha, Hunan, Peoples R China.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.;[Reeves, G. D.] Los Alamos Natl Lab, Space Sci & Applicat Grp, Los Alamos, NM USA.
通讯机构：
[Su, Zhenpeng] U;Univ Sci & Technol China, Dept Geophys & Planetary Sci, Hefei, Peoples R China.;Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei, Peoples R China.
关键词：
butterfly pitch-angle distribution;chorus waves;quasi-linear simulation;Radiation belt;Van Allen Probes;wave/particle interactions
摘要：
Van Allen radiation belt electrons exhibit complex dynamics during geomagnetically active periods. Investigation of electron pitch angle distributions (PADs) can provide important information on the dominant physical mechanisms controlling radiation belt behaviors. Here we report a storm time radiation belt event where energetic electron PADs changed from butterfly distributions to normal or flattop distributions within several hours. Van Allen Probes observations showed that the flattening of butterfly PADs was closely related to the occurrence of whistler-mode chorus waves. Two-dimensional quasi-linear STEERB simulations demonstrate that the observed chorus can resonantly accelerate the near-equatorially trapped electrons and rapidly flatten the corresponding electron butterfly PADs. These results provide a new insight on how chorus waves affect the dynamic evolution of radiation belt electrons. ©2016. American Geophysical Union. All Rights Reserved.
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英文
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Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons
作者：
Su, Zhenpeng* ;Zhu, Hui;Xiao, Fuliang;Zong, Q. -G.;Zhou, X. -Z.;...
期刊：
Nature Communications ,2015年6(1):10096- ISSN：2041-1723
通讯作者：
Su, Zhenpeng
作者机构：
[Su, Zhenpeng; Zheng, Huinan; Wang, Shui; Gao, Zhonglei; Wang, Yuming; Zhu, Hui] Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Anhui, Peoples R China.;[Su, Zhenpeng; Zheng, Huinan; Wang, Shui; Wang, Yuming] Univ Sci & Technol China, Collaborat Innovat Ctr Astronaut Sci & Technol, Hefei 230026, Anhui, Peoples R China.;[Gao, Zhonglei; Zhu, Hui] Univ Sci & Technol China, Sch Earth & Space Sci, Mengcheng Natl Geophys Observ, Hefei 230026, Anhui, Peoples R China.;[Xiao, Fuliang] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410004, Hunan, Peoples R China.;[Hao, Y. -X.; Zhou, X. -Z.; Zong, Q. -G.] Peking Univ, Inst Space Phys & Appl Technol, Beijing 100871, Peoples R China.
通讯机构：
[Su, Zhenpeng] U;Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei 230026, Anhui, Peoples R China.
关键词：
VAN ALLEN PROBES;OUTER-ZONE ELECTRONS;WHISTLER-MODE CHORUS;INNER MAGNETOSPHERE;GEOMAGNETIC STORMS;ACCELERATION;ULF;ENERGIZATION;DYNAMICS;PARTICLE
摘要：
Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.
语种：
英文
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Wave-driven butterfly distribution of Van Allen belt relativistic electrons
作者：
Xiao, Fuliang* ;Yang, Chang;Su, Zhenpeng;Zhou, Qinghua;He, Zhaoguo;...
期刊：
Nature Communications ,2015年6(1):8590 ISSN：2041-1723
通讯作者：
Xiao, Fuliang
作者机构：
[Yang, Chang; Xiao, Fuliang; Zhou, Qinghua; He, Yihua] Changsha Univ Sci & Technol, Sch Phys & Elect Sci, Changsha 410004, Hunan, Peoples R China.;[Su, Zhenpeng] Univ Sci & Technol China, Chinese Acad Sci, Key Lab Basic Plasma Phys, Hefei 230026, Anhui, Peoples R China.;[He, Zhaoguo] Chinese Acad Sci, Ctr Space Sci & Appl Res, Beijing 100190, Peoples R China.;[Baker, D. N.] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA.;[Spence, H. E.] Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.
通讯机构：
[Xiao, Fuliang] C;Changsha Univ Sci & Technol, Sch Phys & Elect Sci, 2nd Sect,South Wanjiali Rd 960, Changsha 410004, Hunan, Peoples R China.
关键词：
GLOBAL DISTRIBUTION;GEOMAGNETIC STORMS;MAGNETOSPHERE;RADIATION;CHORUS;ACCELERATION;PLASMASPHERE;PARTICLES;MODEL;IONS
摘要：
Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90 degrees further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.
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