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Upward propagation of lightning-generated whistler waves into the radiation belts

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Science China(Technological Sciences) 2020年第2期63卷 243-248页

作者： GUO MingYue ZHOU QingHua xiao fuliang LIU Si HE YiHua YANG Chang School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China

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.

关键词： lightning-generated whistler waves radiation belts numerical simulation

Magnetospheric chorus wave instability induced by relativistic Kappa-type distributions

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Science China(Technological Sciences) 2016年第11期59卷 1739-1745页

作者： YANG QiWu YANG Chang HE YiHua LIU Si ZHOU QingHua xiao fuliang School of Physics and Electronic Sciences Changsha University of Science and Technology

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 *** 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 Arel basically decreases as the thermal parameter θ2 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.

关键词： Kappa-type distribution energetic electrons wave-particle interaction chorus wave instability

Butterfly distribution of Earth＇s radiation belt relativistic electrons induced by dayside chorus

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Science China(Technological Sciences) 2018年第2期61卷 212-218页

作者： jin yuyue yang chang he yihua liu si zhou qinghua xiao fuliang school of physics and electronic sciences changsha university of science and technologyChangsha 410004China

Previous theoretical studies have shown that dayside chorus can produce butterfly distribution of energetic electrons in the Earth＇s radiation belts by preferentially accelerating medium pitch angle electrons, but this requires the further confirmation from high- resolution satellite observation. Here, we report correlated Van Allen Probes data on wave and particle during the 1 I-13 April, 2014 geomagnetic storm. We find that a butterfly pitch angle distribution of relativistic electrons is formed around the location L = 4.52, corresponding to the presence of enhanced dayside chorus. Using a Gaussian distribution fit to the observed chorus spectra, we calculate the bounce-averaged diffusion rates and solve two-dimensional Fokker-Planck equation. Numerical results demonstrate that acceleration by dayside chorus can yield the electron flux evolution both in the energy and butterfly pitch angle distribution comparable to the observation, providing a further evidence for the formation of butterfly distribution of relativistic electrons driven by very low frequency （VLF） plasma waves.

关键词： butterfly distribution relativistic electrons radiation belts wave-particle interaction dayside chorus

Generation of simultaneous H^(+)and He^(+)band EMIC waves in the nightside radiation belt

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Science China(Technological Sciences) 2020年第11期63卷 2369-2374页

作者： GUAN ChunYi SHANG XiongJun XIE YanQiong YANG Chang ZHANG Sai LIU Si xiao fuliang School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China

Previous studies have shown that EMIC waves occur preferentially in the afternoon sector of the *** 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 *** the correlated energetic proton data,we present continuous calculations on EMIC wave growth rates along the inward orbit in the region L=5.5–*** modeled growth rate shows remarkable agreement with the observed double band EMIC waves in both temporal and spatial *** current results demonstrate that H^(+)and He^(+)band EMIC waves can be simultaneously excited in the midnight sector under appropriate conditions.

关键词： EMIC waves instability nightside radiation belt Van Allen Probes coordinated observations

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

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Science China(Technological Sciences) 2022年第1期65卷 131-138页

作者： YANG Chang WANG ZongQiang xiao fuliang HE ZhaoGuo XIE YanQiong ZHANG Sai HE YiHua LIU Si ZHOU QingHua School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Sate Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China Planetary Environmental and Astrobiological Research Laboratory(PEARL) School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China College of Meteorology and Oceanography National University of Defense TechnologyNanjing 211101China

Electromagnetic ion cyclotron(EMIC)emission is an efficient mechanism for scattering loss of energetic ***,we report an event that provides both in-situ observation of energetic proton differential fluxes in the inner magnetosphere and precipitation of protons at ionospheric *** the 7-8 September 2015 geomagnetic storm the Van Allen Probes observed strong EMIC waves around L=5 and a distinct decrement in fluxes of tens of keV protons around pitch angles 0°-45°.Meanwhile,precipitating protons at ionospheric altitudes were found to significantly enhanced(by several orders of magnitude),measured by NOAA 18 and 19 when they magnetically linked to the Van Allen *** solving the Fokker-Planck diffusion equation,we show that EMIC waves can efficiently produce loss of energetic protons within about 2 h in the pitch angle range of~0°-45°,comparable to the satellite observations.

关键词： wave-particle interaction EMIC waves energetic proton scattering loss

Observations and parametric study on the role of plasma density on extremely low-frequency chorus wave generation

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Science China(Technological Sciences) 2022年第11期65卷 2649-2657页

作者： HE Qian LIU Si xiao fuliang GAO ZhongLei LI Tong SHANG XiongJun ZHOU QingHua YANG Chang HE YiHua School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China

Extremely low-frequency(ELF)chorus waves with frequencies below 0.1 fcecan cause the scattering losses of relativistic *** studies have suggested that ELF chorus waves are excited by anisotropic electrons with energies up to a few hundred ke ***,we report an interesting event observed using the Van Allen Probes on November 1,2012,where distinct ELF chorus waves occurred exactly corresponding to the enhancement of the plasma *** the correlated data of particles and plasma environments,the continuous calculation of growth rates along the satellite trajectory was *** linear analysis results display a similar pattern to the observation *** further identify the impact of the plasma density on the frequency control of ELF chorus waves,the growth rates were then calculated by only changing the value of the plasma *** calculation results show that the growth rates move to lower frequencies with plasma density enhancement during the *** findings indicate that the increased plasma density has a considerable impact on the wave *** current study can enrich our understanding of the possible role of plasma density on the generation of ELF chorus waves.

关键词： radiation belts plasma density extremely low-frequency chorus waves numerical simulation

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A machine-learning-based electron density (MLED) model in the inner magnetosphere

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Earth and Planetary Physics 2022年第4期6卷 350-358页

作者： QingHua Zhou YunXiang Chen fuliang xiao Sai Zhang Si Liu Chang Yang YiHua He ZhongLei Gao School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering Changsha University of Science and TechnologyChangsha 410114China

Plasma density is an important factor in determining wave-particle interactions in the *** develop a machine-learning-based electron density(MLED)model in the inner magnetosphere using electron density data from Van Allen Probes between September 25,2012 and August 30,*** MLED model is a physics-based nonlinear network that employs fundamental physical principles to describe variations of electron *** predicts the plasmapause location under different geomagnetic conditions,and models separately the electron densities of the plasmasphere and of the *** train the model using gradient descent and backpropagation algorithms,which are widely used to deal effectively with nonlinear relationships among physical quantities in space plasma *** model gives explicit expressions with few parameters and describes the associations of electron density with geomagnetic activity,solar cycle,and seasonal *** various geomagnetic conditions,the electron densities calculated by this model agree well with empirical observations and provide a good description of plasmapause *** MLED model,which can be easily incorporated into previously developed radiation belt models,promises to be very helpful in modeling and improving forecasting of radiation belt electron dynamics.

关键词： background electron density inner magnetosphere machine learning Van Allen Probes observation

On the Functions of Lexical Collocation in English Texts

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校园英语 2016年第15期 214-215页

作者： xiao fuliang Loudi Vocational& Technical College

Lexical collocation, as a cohesive device of an English text, is helpful to make up a cohesive and coherent text. Therefore, to better comprehend English text, different patterns and functions of lexical collocation s... 详细信息

关键词： lexical collocation function English text