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The mid-high latitude whistler mode chorus waves observed around substorm onsets

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Science China(Technological Sciences) 2008年第10期51卷 1648-1658页

作者： YANG JunYing CAO JinBin YAN ChunXiao LI LiuYuan MA YuDuan Key Laboratory of Space Weather Center for Space Science and Applied ResearchChinese Academy of SciencesBeijing 100080China Graduate University of Chinese Academy of Sciences Beijing 100039China

Using the data of LFEW/TC-2, we studied the dawn side chorus around substorm onsets during a strong geomagnetic storm in November 2004. During this storm, LFEW/TC-2 observed 14 dawnside chorus events. Nine of them were associated with substorms and occurred within 40 min around the substorm onsets. The fre-quencies of waves have a very good correlation with the half equatorial electron cyclotron frequencies. chorus can be excited in the region near magnetic equato-rial plane and then propagate to the mid and high latitudes. When the wave fre-quencies reach the local lower hybrid frequencies, chorus can be reflected due to the lower hybrid resonance. The time delay between the chorus and its echo is about 28 min. Previous observations show that the chorus can propagate at most to the magnetic latitudes of 40°. LFEW/ TC-2 found for the first time that the chorus in space could propagate to the magnetic latitude of 70°. Since most of the previous chorus observations are made close to the magnetic equatorial plane, our results are important for the studies of excitation and propagation of whistler mode wave, and relevant relativistic electron acceleration in the magnetosphere.

关键词： chorus substorm onset electron acceleration

Bounce-Averaged Acceleration of Energetic Electrons by Whistler Mode chorus in the Magnetosphere

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Chinese Physics Letters 2007年第1期24卷 294-297页

作者：肖伏良陈良旭周庆华贺慧勇文勇军 School of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410076 State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing 100080

We construct the bounce-averaged diffusion coefficients and study the bounce-averaged acceleration for energetic electrons in gyroresonance with whistler mode chorus. Numerical calculations have been performed for a band of chorus frequency distributed over a standard Gaussian spectrum specifically in the region near L = 4.5, where peaks of the electron phase space density occur. It is found that whistler mode chorus can efficiently accelerate electrons and can increase the phase space density at energies of about 1 MeV by more than one order of magnitude about one day, in agreement with the satellite observations during the recovery phase of magnetic storms.

关键词： chorus Whistlers Diffusion coefficient Magnetosphere Satellite data Geomagnetic storms

Female indris determine the rhythmic structure of the song and sustain a higher cost when the chorus size increases

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Current Zoology 2019年第1期65卷 89-97页

作者： Chiara De Gregorio Anna Zanoli Daria Valente Valeria Torti Giovanna Bonadonna Rose Marie Randrianarison Cristina Giacoma Marco Gamba Dipartimento di Scienze della Vita e Biologia dei Sistemi Universita di Torino via Accademia Albertina Torino Italia Dipartimento di Scienze Chimiche della Vita e della Sostenibilita Ambientale Universita di Parma Parma Italia Group d'Ttude et de Recherche sur les Primates de Madagascar (GERP) Antananarivo Madagascar Departement de Anthropobiologie et Developpement Durable Universite d'Antananarivo Faculte des Sciences Antananarivo Madagascar

Among the behavioral traits shared by some nonhuman primate species and humans there is singing. Unfortunately, our understanding of animals' rhythmic abilities is still in its infancy. Indris are the only lemurs who sing and live in monogamous pairs, usually forming a group with their offspri ng. All adult members of a group usually participate in choruses that are emitted regularly and play a role in advertising territorial occupa ncy and in tergroup spaci ng. Males and females emit phrases that have similar frequency ranges but may differ in their temporal structure. We examined whether the individuals' contribution to the song may change according to chorus size, the total duration of the song or the duration of the individual con tribution using the in ter-on set intervals within a phrase and between phrases. We found that the rhythmic structure of indri's songs depends on factors that are different for males and females. We showed that females have sigrdficantly higher variation in the rhythm of their contribution to the song and that, changes according to chorus size. Our findings indicate that female indris sustain a higher cost of singing than males whe n the nu mber of singers in creases. These results suggest that cross-species investigatio ns will be crucial to un derstanding the evoluti on ary frame in which such sexually dimorphic traits occurred.

关键词： chorus coordination duets lemurs singing synchrony

Multi-satellite observations on the storm-time enhancements of energetic outer zone electron fluxes driven by chorus waves

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Science China(Technological Sciences) 2011年第8期54卷 2209-2216页

作者： HE ZhaoGuo XIAO FuLiang ZONG QiuGang WANG YongFu CHEN LiangXu YUE Chao ZHANG Sai School of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410004 China Institute of Space Physics and Applied Technology Peking University Beijing 100871 China

The evolution of energetic outer zone electron fluxes during the strong magnetic storm on September 28, 2002 is investigated based on the observations of SAMPEX and GOES-10 satellites. The observations of both satellites showed that energetic electron fluxes increased significantly during the storm recovery phase, and reached the maximum on October 6. The 1.5–14 MeV and 2.5–14 MeV electron fluxes observed by SAMPEX peaked around L=3.5 with values of 6×10 2 cm -2 s -1 sr -1 keV -1 and 5×10 3 cm -2 s -1 sr -1 keV -1 , which were about 10 and 8 times the pre-storm values. At the geostationary orbit, the >0.6 MeV and >2 MeV electron fluxes observed by GOES-10 showed enhancement up to 50 and 30 times. The plasma parameters and whistler-mode chorus waves in the outer radiation belt are also analyzed based on the data from Cluster C3 satellite. Cluster C3 satellite went through the outer radiation belt twice from 1 October to 4 October, and observed whistler-mode chorus waves with high intensity (10 -5 –10 -4 nT 2 Hz -1 ). Numerical calculations indicated that the observed chorus waves were in gyro-resonance with the radiation belt electrons. The current observations and calculations provide new evidence for that the gyro-resonance with chorus waves contribute significantly to the buildup of energetic outer zone electron fluxes during storms.

关键词： outer radiation belt energetic electron chorus

Hemispheric Distribution of Lower-band chorus Waves Observed by Van Allen Probes

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空间科学学报 2020年第2期40卷 186-196页

作者： CHENG Xiaowei GU Xudong NI Binbin ZHANG Yang Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072

Whistler mode chorus waves are important electromagnetic emissions due to their dual roles in acceleration and loss processes of Earth's radiation belt electrons.A detailed global survey of lower-band chorus is performed using EMFISIS data from Van Allen Probes in near-equatorial *** addition to the confirmation of the positive correlation of chorus wave intensities to geomagnetic activity and dayside-nightside distribution asymmetry of wave amplitude and occurrence probability,the analysis results find that in statistics lower-band chorus emissions exhibit higher wave occurrence rates and larger normalized peak wave frequencies in the magnetically northern hemisphere but somehow stronger peak wave intensities in the magnetically southern *** overall the differences between the two magnetically hemispheric distributions tend to be not significant,it is important to establish the magnetically hemispheric distribution profiles of lowerband chorus with respect to L-shell,magnetic local time,and geomagnetic latitude for improved understanding of chorus-induced dynamics of radiation belt electrons.

关键词： Lower-band chorus Hemispheric distribution Wave intensities Occurrence rates Normalized peak wave frequency

Excitation of extremely low-frequency chorus emissions: The role of background plasma density

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Earth and Planetary Physics 2019年第1期3卷 1-7页

作者： XiongDong Yu ZhiGang Yuan ShiYong Huang Fei Yao Zheng Qiao John R.Wygant Herbert O.Funsten School of Electronic Information Wuhan University School of Physics and Astronomy University of Minnesota Los Alamos National Laboratory

Low-frequency chorus emissions have recently attracted much attention due to the suggestion that they may play important roles in the dynamics of the Van Allen ***, the mechanism(s) generating these low-frequency chorus emissions have not been well understood..In this letter, we report an interesting case in which background plasma density lowered the lower cutoff frequency of chorus emissions from above 0.1 f_(ce)(typical ordinary chorus) to 0.02 f_(ce)(extremely low-frequency chorus).Those extremely low-frequency chorus waves were observed in a rather dense plasma, where the number density N_e was found to be several times larger than has been associated with observations of ordinary chorus *** suprathermal electrons whose free energy is supplied by anisotropic temperatures, linear growth rates(calculated using in-situ plasma parameters measured by the Van Allen Probes) show that whistler mode instability can occur at frequencies below 0.1 f_(ce) when the background plasma density N_e *** when N_e reaches 90 cm–3 or more, the lowest unstable frequency can extend to 0.02 f_(ce) or even less, which is consistent with satellite ***, our results demonstrate that a dense background plasma could play an essential role in the excitation of extremely lowfrequency chorus waves by controlling the wave growth rates.

关键词： low-frequency chorus emissions anisotropic temperature instability whistler mode Van Allen Probes linear growth rate

Frequency Bands and Gaps of Magnetospheric chorus Waves Generated by Resonant Beam/Plateau Electrons

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Journal of Modern Physics 2022年第6期13卷 864-891页

作者： Konrad Sauer Huayue Chen Eduard Dubinin Quanming Lu CAS Key Laboratory of Geoscience Environment School of Earth and Space Sciences University of Science and Technology of China Hefei China CAS Center of Excellence in Comparative Planetology Hefei China Max-Plnack Institute for Solar System Research G&ouml ttingen Germany

In this paper, the modifications of the whistler dispersion characteristics are investigated which arise if resonant electrons are taken into account. The following chain of processes is emphasized: Generation of whistler waves propagating at different angles to the magnetic field and their nonlinear interaction with resonant electrons result in the appearance of modulated electron beams in the background plasma. As a result, the dispersion characteristics of waves in this new plasma might be significantly changed. By analysing the modified dispersion characteristics these changes are discussed. Supported by particle simulations and space observations, it is assumed that in the electron distribution function at the resonance velocity a plateau-like beam is formed. Because of the weakness of the beam, the term “beam/plateau population (b/p)” is used. By solving the kinetic dispersion relation of whistler waves in electron plasmas with b/p populations, the associated modifications of the whistler dispersion characteristics are presented in diagrams showing, in particular, the frequency versus propagation angle dependence of the excited waves. It is important to point out the two functions of the b/p populations. Because of the bi-directional excitation of whistler waves by temperature anisotropy, one has to distinguish between up- and downstream populations and accordingly between two b/p modes. The interaction of the beam-shifted cyclotron mode ω= Ωe + k⋅Vb (V bVb is the b/p velocity, Ωe: electron cyclotron frequency) with the whistler mode leads to enhanced damping at the ω-k point where they intersect. This is the origin of the frequency gap at half the electron cyclotron frequency (ω~Ωe/2) for quasi-parallel waves which are driven by temperature anisotropy. Furthermore, it is shown that the upstream b/p electrons alone (in the absence of temperature anisotropy) can

关键词： Radiation Belts Waves Whistlers chorus

The Esthetic Connection between chorus Voice and “Form”

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Journal of Contemporary Educational Research 2019年第1期3卷 24-30页

作者： Kehan Teng Department of Theoretical Composition and Command Music CollegeCapital Normal UniversityBeijing201409China Department of Theoretical Composition and Command Central Conservatory of MusicBeijing100031China

Music is the art of sound,while chorus is the art of group vocal *** art takes human voice as the carrier to express thoughts,emotions,and artistic images through ***,unified,balanced sound gives people the enjoyment of beauty and brings people-related pictorial *** a unique form of vocal music art,chorus is also a comprehensive stage art belonging to the category of performance,which is a sister art belonging to the same and different families,such as dance and *** the visual arts such as dance and drama,the melody,timbre,and harmony of music match the figures appearing on the stage or *** that when we hear some kind of music there will belyrical beautiful,strong magnificent,or lively jumping,dark melancholy and so on feelings and *** ancient to modern times,in daily life,people sang and danced scenes were also their immediate reflection of music aesthetic *** of these aesthetic experiences are vague and some are *** example:We may think some music is humorous or sad,but when people hear the music,such as"the devil into the village",we will think of the scene in that *** associated the Anti-Japanese *** chorus,the influence of“form”on the aesthetic feeling of sound,or from the perspective of reverse thinking,canbe said to be the aesthetic expression of“form”by sound,which can relate to the breath of singing,the resonance position and the effect and change of the expression *** audience can feel the chorus’s expression of aesthetic emotion directly from their hearing and then has a significant influence on the music sound and singing *** this paper,through the association of“form”to sound and aesthetic influence,with the help of some in the dance to tighten the intuitive posture,to chorus vertical sound *** from the identity of visual perception and sound perception,this paper tries to understand our requirements for chorus singing from a reverse pers

关键词： chorus sound“form” auditory perceptual style aesthetic relation

Radiation belt electron scattering by whistler-mode chorus in the Jovian magnetosphere: Importance of ambient and wave parameters

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Earth and Planetary Physics 2018年第1期2卷 1-14页

作者： BinBin Ni Jing Huang YaSong Ge Jun Cui Yong Wei XuDong Gu Song Fu Zheng Xiang ZhengYu Zhao Department of Space Physics School of Electronic Information Wuhan University Lunar and Planetary Science Laboratory Macao University of Science and Technology-Partner Laboratory of Key Laboratory of Lunar and Deep Space Exploration Chinese Academy of Sciences Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences School of Atmospheric Sciences Sun Yat-Sen University

Whistler-mode chorus waves are regarded as an important acceleration mechanism contributing to the formation of relativistic and ultra-relativistic electrons in the Jovian radiation belts. Quantitative determination of the chorus wave driven electron scattering effect in the Jovian magnetosphere requires detailed information of both ambient magnetic field and plasma density and wave spectral property, which however cannot be always readily acquired from observations of existed missions to Jupiter. We therefore perform a comprehensive analysis of the sensitivity of chorus induced electron scattering rates to ambient magnetospheric and wave parameters in the Jovian radiation belts to elaborate to which extent the diffusion coefficients depend on a number of key input parameters. It is found that quasi-linear electron scattering rates by chorus can be strongly affected by the ambient magnetic field intensity, the wave latitudinal coverage, and the peak frequency and bandwidth of the wave spectral distribution in the Jovian magnetosphere, while they only rely slightly on the background plasma density profile and the peak wave normal angle, especially when the wave emissions are confined at lower latitudes. Given the chorus wave amplitude, chorus induced electron scattering rates strongly depend on Jovian L-shell to exhibit a tendency approximately proportional to L_J^3. Our comprehensive analysis explicitly demonstrates the importance of reliable information of both the ambient magnetospheric state and wave distribution property to understanding the dynamic electron evolution in the Jovian radiation belts and therefore has implications for future mission planning to explore the extreme particle radiation environment of Jupiter and its satellites.

关键词： Jovian radiation belts whistler-mode chorus resonant wave-particle interactions magnetospheric state