Kinetic evidence of magnetic reconnection due to Kelvin‐Helmholtz waves

Li, Wenya; André, Mats; Khotyaintsev, Yuri; Vaivads, A.; Graham, Daniel B.; Toledo‐Redondo, Sergio; Norgren, Cecilia; Henri, Pierre; Wang, C.; Tang, Binbin; Lavraud, B.; Vernisse, Y.; Turner, D. L.; Burch, J. L.; Torbert, R. B.; Magnes, W.; Russell, C. T.; Blake, J. B.; Mauk, B. H.; Giles, B. L.; Pollock, C. J.; Fennell, J. F.; Jaynes, A. N.; Avanov, L. A.; Dorelli, J.; Gershman, D. J.; Paterson, W. R.; Saito, Y.; Strangeway, R. J.

doi:10.1002/2016gl069192

Cited by 61 publications

(74 citation statements)

References 50 publications

(68 reference statements)

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“…However, due to the limitation of temporal resolutions, such observations had been unable to provide direct and conclusive evidence. The first direct evidence of ongoing magnetic reconnection at the trailing edges of KH waves, where the local magnetic shear is enlarged and the current sheet is compressed to ion scale, is recorded by MMS Li et al, 2016), and the MMS observations confirm previous studies from both field and particle measurements. But whether such reconnection can result in the generation of flux ropes has not been further examined by MMS.…”

Section: Introductionsupporting

confidence: 76%

“…The boundary conditions are KH unstable based on the linear theory (Chandrasekhar, 1961), and the dominant period of these KH waves is ∼ 44 s ( T KH ) from ion density and magnetic field perturbations. At the trailing edges of these surface waves, the magnetic shear could suddenly increase, providing favorable conditions for magnetic reconnection, which has been reported in another KH event on 8 September 2015 Li et al, 2016). In this event, signatures of reconnec- Figure 1.…”

Section: Observationmentioning

confidence: 99%

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Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

Tang

Wang

et al. 2018

Ann. Geophys.

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Abstract. We report an ion-scale magnetic flux rope (the size of the flux rope is ∼ 8.5 ion inertial lengths) at the trailing edge of Kelvin-Helmholtz (KH) waves observed by the Magnetospheric Multiscale (MMS) mission on 27 September 2016, which is likely generated by multiple X-line reconnection. The currents of this flux rope are highly filamentary: in the central flux rope, the current flows are mainly parallel to the magnetic field, supporting a local magnetic field increase at about 7 nT, while at the edges the current filaments are predominantly along the antiparallel direction, which induce an opposing field that causes a significant magnetic depression along the axis direction (> 20 nT), meaning the overall magnetic field of this flux rope is depressed compared to the ambient magnetic field. Thus, this flux rope, accompanied by the plasma thermal pressure enhancement in the center, is referred to as a crater type. Intense lower hybrid drift waves (LHDWs) are found at the magnetospheric edge of the flux rope, and the wave potential is estimated to be ∼ 17 % of the electron temperature. Though LHDWs may be stabilized by the mechanism of electron resonance broadening, these waves could still effectively enable diffusive electron transports in the cross-field direction, corresponding to a local density dip. This indicates LHDWs could play important roles in the evolution of crater flux ropes.

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Section: Introductionsupporting

confidence: 76%

Section: Observationmentioning

confidence: 99%

Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

Tang

Wang

et al. 2018

Ann. Geophys.

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“…For antiparallel reconnection sites on the flanks, this turbulence could be related to the growth of Kelvin‐Helmholtz instabilities (KHIs) [see Hasegawa et al ., ] set up by inhomogeneous flow shear across the magnetopause. The magnetosheath flow along the flanks is greater than the flow speed near the subsolar point, making the flanks more conducive to KHIs that can then have localized regions of reconnection within the resulting vortices [ Eriksson et al ., ; Li et al ., ]. High flow shear has also been suggested to play a role in forming FTEs [ Chen et al ., ], and so may be related to the observations on the flanks in this study.…”

Section: Discussionmentioning

confidence: 99%

Occurrence frequency and location of magnetic islands at the dayside magnetopause

et al. 2017

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Simulations of magnetic reconnection often predict the formation of magnetic islands forming and propagating out through the reconnection exhaust region. However, to date, only a few observations of magnetic islands at the Earth's magnetopause have been identified and analyzed. Crossings near reconnection sites at the dayside magnetopause by Cluster from 2001 to 2009 are examined in a systematic effort to determine the frequency and location of magnetic islands. Using the maximum magnetic shear model as a guide for the distance to the reconnection site, 47 magnetopause crossings within 3 RE of the predicted reconnection site are examined. The occurrence of island structures in the reconnection exhaust is investigated in the context of how the type of reconnection, antiparallel or component, affects the frequency of formation of the islands. For Cluster magnetopause crossings confirmed to be near reconnection sites, island signatures, primarily bidirectional streaming electrons in the magnetosheath boundary layer, are seen for approximately 85% of the crossings and are common features for both antiparallel and component reconnection.

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“…They are often, but not always, observed in the presence of magnetic field fluctuations. This may mean that their generation is tied to ULF or kinetic Alfven waves [ Chaston et al ., ] or possibly related to Kelvin Helmholtz wave activity like that observed on MMS by Li et al ., [, this issue] and Eriksson et al ., [, this issue] or vortices [ Hones et al ., ] close to the magnetopause boundary. As Figure shows, the measured perpendicular flux levels were at or below FEEPS background from cosmic rays, ≤0.1/(cm 2 s sr keV) for 126 keV, while the field‐aligned fluxes were intense.…”

Section: Discussionmentioning

confidence: 99%

Microinjections observed by MMS FEEPS in the dusk to midnight region

Fennell

Turner

Lemon

et al. 2016

Geophysical Research Letters

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Energetic electron injections are commonly observed in the premidnight to dawn regions in association with substorms. However, successive electron injections are generally separated in time by hours and are rarer in the dusk region of the inner magnetosphere. Early MMS energetic electron data taken in the dusk to premidnight regions above ~9 RE show many clusters of electron injections. These injections of 50–400 keV electrons have energy dispersion signatures indicating that they gradient and curvature drifted from earlier local times. We focus on burst rate data starting near 21:00 UT on 6 August 2015. A cluster of ~40 electron injections occurred in the following 4 h interval. The highest‐resolution data showed that the electrons in the injections were trapped and had bidirectional field‐aligned angular distributions. These injection clusters are a new phenomenon in this region of the magnetosphere.

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Kinetic evidence of magnetic reconnection due to Kelvin‐Helmholtz waves

Cited by 61 publications

References 50 publications

Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

Magnetic depression and electron transport in an ion-scale flux rope associated with Kelvin–Helmholtz waves

Occurrence frequency and location of magnetic islands at the dayside magnetopause

Microinjections observed by MMS FEEPS in the dusk to midnight region

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