Turbulence in the Earth's cusp region: The <i>k</i>‐filtering analysis

Wang, Tieyan; Cao, Jinbin; Fu, H. S.; Liu, Wenlong; Dunlop, M. W.

doi:10.1002/2014ja019997

Cited by 13 publications

(11 citation statements)

References 78 publications

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“…1,9,11,54,55 In particular, the physical nature in the auroral ionosphere and magnetosphere can be well explained by in situ observations of KAWs with the polar orbiting satellites, Freja, FAST, Cluster. 18,19,52,[56][57][58][59][60][61] Both in situ measurements and numerical simulation investigations provide further evidence that KAWs can be responsible for the field-aligned energization of electrons that drive bright aurora. 51,[62][63][64] KAWs are dissipative as well as dispersive waves because their perpendicular wavelengths have scales comparable to the microscopic kinetic scales of particles, such as the ion gyroradius or the electron inertial length.…”

Section: Summary and Discussionmentioning

confidence: 89%

Generation of kinetic Alfven waves in the high-latitude near-Earth magnetotail: A global hybrid simulation

et al. 2015

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In this paper, effects of a fast flow in the tail plasma sheet on the generation of kinetic Alfven waves (KAWs) in the high-latitude of the near-Earth magnetotail are investigated by performing a two-dimensional (2-D) global-scale hybrid simulation, where the plasma flow is initialized by the E Â B drift near the equatorial plane due to the existence of the dawn-dusk convection electric field. It is found that firstly, the plasma sheet becomes thinned and the dipolarization of magnetic field appears around ðx; zÞ ¼ ðÀ10:5R E ; 0:3R E Þ, where R E is the radius of the Earth. Then, shear Alfven waves are excited in the plasma sheet, and the strong earthward flow is braked by the dipole-like magnetic field. These waves propagate along the magnetic field lines toward the polar regions later. Subsequently, KAWs with k ? ) k k are generated in the high-latitude magnetotail due to the existence of the non-uniformity of the magnetic field and density in the polar regions. The ratio of the electric field to the magnetic field in these waves is found to obey the relation ðdE z Þ=ðdB y Þ $ x=k k of KAWs. Our simulation provides a mechanism for the generation of the observed low-frequency shear Alfven waves in the plasma sheet and kinetic Alfven waves in the high-latitude near-Earth magnetotail, whose source is suggested to be the flow braking in the lowlatitude plasma sheet. V C 2015 AIP Publishing LLC. [http://dx.

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Section: Summary and Discussionmentioning

confidence: 89%

Generation of kinetic Alfven waves in the high-latitude near-Earth magnetotail: A global hybrid simulation

et al. 2015

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“…We expect this relation to be present here and thus take similar procedures as in Perrone et al (2017) to search for the intermittent events. The first step is to reconstruct the fluctuations using the band-pass filter based on wavelet transforms (Torrence & Compo 1998;He et al 2012;Wang et al 2014;Perrone et al 2016). The magnetic field fluctuations are thus defined as,…”

Section: Event Overviewmentioning

confidence: 99%

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Wang

Alexandrova

Perrone

et al. 2019

ApJL

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Alfvén vortex is a multi-scale nonlinear structure which contributes to intermittency of turbulence. Despite previous explorations mostly on the spatial properties of the Alfvén vortex (i.e., scale, orientation, and motion), the plasma characteristics within the Alfvén vortex are unknown. Moreover, the connection between the plasma energization and the Alfvén vortex still remains unclear. Based on high resolution in-situ measurement from the Magnetospheric Multiscale (MMS) mission, we report for the first time, distinctive plasma features within an Alfvén vortex. This Alfvén vortex is identified to be two-dimensional (k ⊥ k ) quasi-monopole with a radius of 10 proton gyroscales. Its magnetic fluctuations δB ⊥ are anti correlated with velocity fluctuations δV ⊥ , thus the parallel current density j and flow vorticity ω are anti-aligned. In different part of the vortex (i.e., edge, middle, center), the ion and electron temperatures are found to be quite different and they behave in the reverse trend: the ion temperature variations are correlated with j , while the electron temperature variations are correlated with ω . Furthermore, the temperature anisotropies, together with the non-Maxwellian kinetic effects, exhibit strong enhancement at peaks of |ω |(|j |) within the vortex. Comparison between observations and numerical/theoretical results are made. In addition, the energy-conversion channels and the compressibility associated with the Alfvén vortex are discussed. These results may help to understand the link between coherent vortex structures and the kinetic processes, which determines how turbulence energy dissipate in the weakly-collisional space plasmas.

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“…This technique provides the best estimation of the Magnetic Field Energy Distribution (MFED) P ( f 0 , k ) in the four‐dimensional space, under the assumption of weak stationarity and space homogeneity of the time series data. It can also disentangle the wave mode directly from the observed temporal and spatial variation [ Huang et al , ; Wang et al , ]. The “elongation” E and the “planarity” P of the Cluster tetrahedron are 0.21 and 0.28, respectively.…”

Section: Observations and Analysismentioning

confidence: 99%

Compressible turbulence with slow‐mode waves observed in the bursty bulk flow of plasma sheet

Wang

Cao

et al. 2016

Geophysical Research Letters

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In this paper, we report the evidence of compressible turbulence with slow‐mode waves in a bursty bulk flow of plasma sheet. This compressible turbulence is characterized by a multiscale (1–60 s) anticorrelation between plasma density and magnetic field strength. Besides, the magnetic compressibility spectrum stays nearly constant at all the measured frequencies. Furthermore, the turbulence energy distributions are anisotropic with k⊥ > k//, and the dispersion relation is consistent with slow‐mode prediction. The fluctuations of density and magnetic field have similar double slope spectrum and kurtosis. These results suggest that the slow waves are involved in the intermittent turbulence cascade from MHD to ion kinetic scales, which may have significant implications for the energy transfer in the plasma sheet.

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Turbulence in the Earth's cusp region: The k‐filtering analysis

Cited by 13 publications

References 78 publications

Generation of kinetic Alfven waves in the high-latitude near-Earth magnetotail: A global hybrid simulation

Generation of kinetic Alfven waves in the high-latitude near-Earth magnetotail: A global hybrid simulation

Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex

Compressible turbulence with slow‐mode waves observed in the bursty bulk flow of plasma sheet

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