Global features of Kelvin‐Helmholtz waves at the magnetopause for northward interplanetary magnetic field

Li, Wenya; Wang, Chi; Tang, Binbin; Guo, Xiaocheng; Lin, Dong

doi:10.1002/jgra.50498

Cited by 31 publications

(38 citation statements)

References 46 publications

(84 reference statements)

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“…An explanation for this could simply be due to inaccuracies in the angle calculation for this region. Along the flanks, the magnetic topology is affected by Kelvin‐Helmholtz instabilities [ Kivelson and Pu , ; Li et al ., ]. These instabilities will cause the background magnetic field direction to vary, which could lead to an error in the defined background field direction [ Kivelson and Pu , ].…”

Section: Discussionmentioning

confidence: 99%

A statistical study of EMIC waves observed by Cluster: 1. Wave properties

et al. 2015

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Electromagnetic ion cyclotron (EMIC) waves are an important mechanism for particle energization and losses inside the magnetosphere. In order to better understand the effects of these waves on particle dynamics, detailed information about the occurrence rate, wave power, ellipticity, normal angle, energy propagation angle distributions, and local plasma parameters are required. Previous statistical studies have used in situ observations to investigate the distribution of these parameters in the magnetic local time versus L‐shell (MLT‐L) frame within a limited magnetic latitude (MLAT) range. In this study, we present a statistical analysis of EMIC wave properties using 10 years (2001–2010) of data from Cluster, totaling 25,431 min of wave activity. Due to the polar orbit of Cluster, we are able to investigate EMIC waves at all MLATs and MLTs. This allows us to further investigate the MLAT dependence of various wave properties inside different MLT sectors and further explore the effects of Shabansky orbits on EMIC wave generation and propagation. The statistical analysis is presented in two papers. This paper focuses on the wave occurrence distribution as well as the distribution of wave properties. The companion paper focuses on local plasma parameters during wave observations as well as wave generation proxies.

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Section: Discussionmentioning

confidence: 99%

A statistical study of EMIC waves observed by Cluster: 1. Wave properties

et al. 2015

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“…Previous MHD simulations of Merkin et al () and Li et al () have evidenced the formation of one row of K‐H vortices rotating in one direction before x ~ 0 (near the DD line) defined in Figures and . This row evolves into two rows of staggered vortices rotating in relatively opposite directions after x ~ 0 in the 3‐D global MHD simulation, for example, Figures 7 and 8 of Merkin et al ().…”

Section: Flow Regime Karman Vortex and Vortex Structuresmentioning

confidence: 77%

“…Some vortex features like their wavelengths are consistent with the K‐H MHD simulations (Hasegawa et al, ). A few recent previous global MHD simulations (Li et al, ; Merkin et al, ) have observed two rows of vortex trains, one located in the magnetopause side and the other in the magnetosphere side (Li et al, ; Merkin et al, ). These vortices are rotating, respectively, clockwise and counterclockwise around the core axis, which is perpendicular to the uniform flow.…”

Section: Introductionmentioning

confidence: 99%

Identifying 3‐D Vortex Structures At/Around the Magnetopause Using a Tetrahedral Satellite Configuration

et al. 2018

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Identifying vortices is the key to understanding the turbulence in plasma shear layers. This paper aims to provide general guidelines for identifying 3‐D vortex structures. Currently, no single precise definition of a vortex is universally accepted, despite the significance of vortices in fluid and plasma dynamics. Recently, various vortex identification methods using Galilean invariance have been proposed by numerous researchers. These methods are general for different fluid and plasma visualization applications. In the present paper, we describe how we have identified 105 vortex structures by applying these methods to Cluster data near the duskside of the magnetopause. Four sets of Cluster satellite magnetic field data are used to linearly approximate the magnetic field. We identify the 3‐D magnetic vortex structures by using various vortex identification criteria as follows: (i) the first criterion is Q‐criterion that defines vortices as regions in which the vorticity energy prevails over other energies; (ii) the second criterion is the λ2‐criterion that is related to the minus eigenvalue of the Hessian matrix of the pressure terms; and (iii) the third criterion called the geometrical line‐type method requires the existence of Galilean‐invariant vortex core inside the four Cluster tetrahedral regions. In reality, both Q‐ and λ2‐criteria are also related to Galilean invariance. The present analysis evidences that the geometrical line‐type method is more precise than the other two using Cluster satellite magnetic field data.

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“…MHD simulations [ Li et al , ] showed that KHW mainly develops at low latitudes, and its growth rate significantly decreases toward high latitudes [ Contin et al , ]. Therefore, by choosing a plane with a relatively high θ angle ( θ h ) as a reference, the difference of the X‐ray intensity between this plane and planes with lower latitudes reasonably approximates the KHW‐induced signal d I :

normald I (φ, θ) = I (φ, θ) - I (φ, θ_{h}) .

…”

Section: Numerical Resultsmentioning

confidence: 99%

X‐ray imaging of Kelvin‐Helmholtz waves at the magnetopause

et al. 2015

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This paper simulates the Kelvin‐Helmholtz wave (KHW)‐induced X‐ray emissions at the low‐latitude magnetopause based on a global MHD code. A method is proposed to extract the KHW information from the X‐ray intensity measured by a hypothetical X‐ray telescope onboard a satellite assumed with a low Earth orbit. Specifically, the X‐ray intensity at high latitude is subtracted from the intensity map as a background to highlight the role of KHW. Using this method, global features of KHW such as the vortex velocity, perturbation degree, spatial distribution, and temporal evolution could be evaluated from the X‐ray intensity map. The validity of this method during intervals of solar wind disturbances is also verified. According to the simulation results, X‐ray imaging of KHW is suggested as a promising observation technique to essentially “see” the large‐scale configuration and evolution of KHW for the first time.

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Global features of Kelvin‐Helmholtz waves at the magnetopause for northward interplanetary magnetic field

Cited by 31 publications

References 46 publications

A statistical study of EMIC waves observed by Cluster: 1. Wave properties

A statistical study of EMIC waves observed by Cluster: 1. Wave properties

Identifying 3‐D Vortex Structures At/Around the Magnetopause Using a Tetrahedral Satellite Configuration

X‐ray imaging of Kelvin‐Helmholtz waves at the magnetopause

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