A case study of Kelvin–Helmholtz vortices on both flanks of the Earth's magnetotail

Nishino, Masaki N.; Hasegawa, Hiroshi; Fujimoto, M.; Saito, Y.; Mukai, T.; Dandouras, I.; Rème, H.; Retinò, Alessandro; Nakamura, R.; Lucek, E.; Schwartz, S. J.

doi:10.1016/j.pss.2010.03.011

Cited by 22 publications

(27 citation statements)

References 40 publications

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“…Hasegawa et al (2007aHasegawa et al ( , 2009b and Nishino et al (2011) indeed argued that the widths of the reconstructed vortices of order ∼ 1R E are consistent with the roll-up of the KH vortices (e.g., Fig. 7).…”

Section: Single-spacecraft Detection Of Rolled-up Vorticessupporting

confidence: 61%

“…The technique has been applied to flow vortices in the flank LLBL (Hasegawa et al, 2007a(Hasegawa et al, , 2009bEriksson et al, 2009;Nishino et al, 2011) and those observed in the tail plasma sheet (Tian et al, 2010). Figure 7 shows the streamlines reconstructed from C1 data when the spacecraft traversed rolled-up vortices in the dusk-flank LLBL.…”

Section: Structures With Flow Transverse To the Magnetic Fieldmentioning

confidence: 99%

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Structure and Dynamics of the Magnetopause and Its Boundary Layers

Hasegawa¹

2012

Monogr. Environ. Earth Planets

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The magnetopause is the key region in space for the transfer of solar wind mass, momentum, and energy into the magnetosphere. During the last decade, our understanding of the structure and dynamics of Earth's magnetopause and its boundary layers has advanced considerably, thanks largely to the advent of multi-spacecraft missions such as Cluster and THEMIS. Moreover, various types of physics-based techniques have been developed for visualizing two-or threedimensional plasma and field structures from data taken by one or more spacecraft, providing a new approach to the analysis of the spatiotemporal properties of magnetopause processes, such as magnetic reconnection and the Kelvin-Helmholtz instability (KHI). Information on the size, shape, orientation, and evolution of magnetic flux ropes or flow vortices generated by those processes can be extracted from in situ measurements. Observations show that magnetopause reconnection can be globally continuous for both southward and northward interplanetary magnetic field (IMF) conditions, but even under such circumstances, more than one X-line may exist within a certain (low-latitude or high-latitude) portion on the magnetopause and some X-lines may retreat anti-sunward. The potential global effects of such behavior are discussed. An overview is also given of the identification, excitation, evolution, and possible consequences of the magnetopause KHI: there is evidence for nonlinear KHI growth and associated vortex-induced reconnection under northward IMF. Observation-based estimates indicate that reconnection tailward of both polar cusps can be the dominant mechanism for solar wind plasma entry into the dayside magnetosphere under northward IMF. However, the mechanism by which the transferred plasma is transported into the central portion of the magnetotail, and the role of magnetopause processes in this transport, remain unclear. Future prospects of magnetopause and other relevant studies are also discussed.

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Section: Single-spacecraft Detection Of Rolled-up Vorticessupporting

confidence: 61%

Section: Structures With Flow Transverse To the Magnetic Fieldmentioning

confidence: 99%

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Hasegawa¹

2012

Monogr. Environ. Earth Planets

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“…These studies reported the existence of a twocomponent ion energy distribution, comprised of a cold magnetosheath and a hotter magnetospheric population on the dusk side and a more condensed/mixed distribution on the dawn flank. Nishino et al (2011) reported simultaneous observations of KHI driven waves at both flanks of the magnetosphere, with simultaneous conjugate flank observations from Geotail and Cluster. The macroscopic appearance of the vortex structures themselves was roughly symmetric, although at the microscopic level there were clear differences, with a mixed like appearance of distributions around the dawn vortices and a two-component distribution found on the dusk side.…”

Section: Discussionmentioning

confidence: 87%

Spatial distribution of rolled up Kelvin-Helmholtz vortices at Earth's dayside and flank magnetopause

et al. 2012

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Abstract. The Kelvin-Helmholtz Instability (KHI) can drive waves at the magnetopause. These waves can grow to form rolled-up vortices and facilitate transfer of plasma into the magnetosphere. To investigate the persistence and frequency of such waves at the magnetopause we have carried out a survey of all Double Star 1 magnetopause crossings, using a combination of ion and magnetic field measurements. Using criteria originally used in a Geotail study made by Hasegawa et al. (2006) (forthwith referred to as H2006), 17 candidate events were identified from the entire TC-1 mission (covering ∼623 orbits where the magnetopause was sampled), a majority of which were on the dayside of the terminator. The relationship between density and shear velocity was then investigated, to identify the predicted signature of a rolled up vortex from H2006 and all 17 events exhibited some level of rolled up behavior. The location of the events had a clear dawn-dusk asymmetry, with 12 (71 %) on the post noon, dusk flank suggesting preferential growth in this region.

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“…Sonnerup, 1974;Sonnerup et al, 1981;Scurry and Russell, 1991;Raeder, 2005, 2007;Kessel et al, 1996;Lockwood and Smith, 1992;Lavraud and Borovsky, 2008;, and also the associated location of the Earth's cusps (Lavraud et al, , 2005a, although the large-scale properties of MR, such as the factors controlling its occurrence and the exact mechanism controlling transient reconnection, are still not very well understood. During purely northward IMF, the main transport process remains uncertain, since competing mechanisms may operate, such as dual lobe reconnection Onsager et al, 2001;Lavraud et al, 2005bLavraud et al, , 2006, diffusion, and plasma transport via Kelvin-Helmholtz waves (Hasegawa et al, 2004a;Taylor and Lavraud, 2008;Nishino et al, 2011). Multi-point measurements at the magnetopause are therefore crucial for further investigation of these effects, since multiple MR sites may exist (Dunlop et al, 2009;Pu et al, 2007) and/or different transport mechanisms may occur simultaneously .…”

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Magnetopause reconnection across wide local time

et al. 2011

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Abstract. During April to July 2007 a combination of 10 spacecraft provided simultaneous monitoring of the dayside magnetopause across a wide range of local times. The array of four Cluster spacecraft, separated at large distances (10 000 km), were traversing the dawn-side magnetopause at high and low latitudes; the five THEMIS spacecraft were often in a 4 + 1 grouped configuration, traversing the low latitude, dusk-side magnetosphere, and the Double star, TC-1 spacecraft was in an equatorial orbit between the local times of the THEMIS and Cluster orbits. We show here a number of near simultaneous conjunctions of all 10 spacecraft at the magnetopause. One conjunction identifies an extended magnetic reconnection X-line, tilted in the low latitude, sub-solar region, which exists together with active anti-parallel reconnection sites extending to locations on the dawn-side flank. Oppositely moving FTE's are observed on all spacecraft, consistent with the initially strong IMF B y conditions and the comparative locations of the spacecraft both dusk-ward and dawn-ward of noon. Comparison with other conjunctions of magnetopause crossings, which are also distributed Correspondence to: M. W. Dunlop (m.w.dunlop@rl.ac.uk) over wide local times, supports the result that reconnection activity may occur at many sites simultaneously across the sub-solar and flank magnetopause, but linked to the large scale (extended) configuration of the merging line; broadly depending on IMF orientation. The occurrence of MR therefore inherently follows a "component" driven scenario irrespective of the guide field conditions. Some conjunctions allow the global magnetopause response to IMF changes to be observed and the distribution of spacecraft can directly confirm its shape, motion and deformation at local noon, dawn and dusk-side, simultaneously.

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A case study of Kelvin–Helmholtz vortices on both flanks of the Earth's magnetotail

Cited by 22 publications

References 40 publications

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Spatial distribution of rolled up Kelvin-Helmholtz vortices at Earth's dayside and flank magnetopause

Magnetopause reconnection across wide local time

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