Numerical Evidence of Undriven, Fast Reconnection in the Solar-Wind Interaction with Earth’s Magnetosphere: Formation of Electromagnetic Coherent Structures

Faganello, Matteo; Califano, Francesco; Пегораро, Ф.

doi:10.1103/physrevlett.101.105001

Cited by 38 publications

(36 citation statements)

References 27 publications

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“…The development of vortex structures due to Kelvin-Helmholtz (K-H) instability in the shear flow of the magnetosheath/magnetopause has been studied by Matsumoto and Hoshino (2006) in the case of magnetic field perpendicular to the flow speed, and by Faganello et al (2008) in the case magnetic field oblique with respect to the flow speed (that is, a component of B parallel to the flow is present). It is found that a large scale vortex chain is formed first, and then small scale vortices due to secondary K-H instability and to Rayleigh-Taylor instability driven by the density gradient (Matsumoto and Hoshino 2006), or secondary reconnection due to the formation of magnetic inversion layers in between the large scale vortices (Faganello et al 2008). In the final stage, both simulations attain a multi-scale perturbed structure, which is very similar to the results of a turbulent cascade.…”

Section: Numerical Modeling Of Turbulence Effectsmentioning

confidence: 99%

Magnetic Turbulence in the Geospace Environment

et al. 2010

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Magnetic turbulence is found in most space plasmas, including the Earth's magnetosphere, and the interaction region between the magnetosphere and the solar wind. Recent spacecraft observations of magnetic turbulence in the ion foreshock, in the magnetosheath, in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere are reviewed. It is found that: 1. A large share of magnetic turbulence in the geospace environment is generated locally, as due for instance to the reflected ion beams in the ion foreshock, to temperature anisotropy in the magnetosheath and the polar cusp regions, to velocity shear in the magnetosheath and magnetotail, and to magnetic reconnection at the magnetopause and in the magnetotail. 2. Spectral indices close to the Kolmogorov value can be recovered for low frequency turbulence when long enough intervals at relatively constant flow speed are analyzed in the magnetotail, or when fluctuations in the magnetosheath are G. Zimbardo et al. considered far downstream from the bow shock. 3. For high frequency turbulence, a spectral index α 2.3 or larger is observed in most geospace regions, in agreement with what is observed in the solar wind. 4. More studies are needed to gain an understanding of turbulence dissipation in the geospace environment, also keeping in mind that the strong temperature anisotropies which are observed show that wave particle interactions can be a source of wave emission rather than of turbulence dissipation. 5. Several spacecraft observations show the existence of vortices in the magnetosheath, on the magnetopause, in the magnetotail, and in the ionosphere, so that they may have a primary role in the turbulent injection and evolution. The influence of such a turbulence on the plasma transport, dynamics, and energization will be described, also using the results of numerical simulations.

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Section: Numerical Modeling Of Turbulence Effectsmentioning

confidence: 99%

Magnetic Turbulence in the Geospace Environment

et al. 2010

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“…[] have summarized two types of this so‐called vortex‐induced reconnection (VIR). Type‐I VIR occurs when the in‐plane field is initially antiparallel across the velocity shear layer [e.g., Pu et al ., ; Knoll and Chacón , ; Nakamura et al ., , ], while type‐II VIR is driven within the highly rolled‐up vortex where the wrapped field lines produce thin current layers [e.g., Nykyri and Otto , ; Nakamura and Fujimoto , ; Faganello et al ., ]. Since type‐I VIR is the main focus of this study, for the rest of this paper, we simply refer to this as VIR.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional dynamics of vortex‐induced reconnection and comparison with THEMIS observations

et al. 2013

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[1] The entry of solar wind into the magnetosphere is strongly influenced by kinetic-scale boundary layers where the rapid variation in the magnetic field and/or velocity can drive transport. In current layers with strong Alfvénic velocity shear, the generation of vortices from the Kelvin-Helmholtz instability can drive magnetic reconnection even in broader current sheets by locally compressing these layers as the vortices develop. Previous two-dimensional (2-D) fully kinetic simulations of this vortex-induced reconnection process have demonstrated the copious formation of magnetic islands in regions of strongly compressed current between the vortices. Here we describe the first three-dimensional (3-D) fully kinetic simulations of this process and demonstrate that the compressed current sheets give rise to magnetic flux ropes over a range of oblique angles and along the entire extent of the compressed current layer around the periphery of the vortex. These flux ropes propagate with the shear flow and eventually merge with the vortex. Over longer time scales, this basic scenario is repeated as the vortices drive new compressed current sheets. In the final stage, the vortices undergo a merging process that drives new compressed current sheets and flux ropes. Based on these simulations, a simple model is proposed that predicts the size of these flux ropes relative to their parent vortex. Both the relative sizes as well as the structure of the profiles across the vortex are in reasonable agreement with Time History of Events and Macroscale Interactions (THEMIS) observations at the Earth's low-latitude magnetopause.

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“…These conclusions are drawn for the diffusion process, and does not rule out the possible role of KH instability to trigger magnetic reconnection and associated mass transfer. 35,36 The next step in this study is to identify the respective role of electric and magnetic fluctuation, as well as their coupling. A robust methodology to identify and subtract the mean fluid velocity would also allow to investigate the j ?…”

Section: Discussionmentioning

confidence: 99%