Location of Magnetic Reconnection in the Magnetotail

Nagai, T.

doi:10.1007/s11214-006-6216-4

Cited by 25 publications

(24 citation statements)

References 40 publications

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“…Each plot has the same color scale of pressure, so it is clear that the run with the Roe solver has a much stronger pressure on the night side. This pressure causes a stretching of the magnetic field-lines in the tail, resulting in a much longer tail, which is more consistent with observations of the tail length (Sergeev et al, 2000;Nagai et al, 2001Nagai et al, , 2005Nagai, 2006;Slavin et al, 2003). The stretching of the field-lines also serves to allow the plasma to be adiabatically heated more as it is advected in from the tail, thereby increasing the pressure in the inner magnetosphere, resulting in a nonlinear feedback.…”

Section: Numerical Flux Functionssupporting

confidence: 79%

Numerical considerations in simulating the global magnetosphere

et al. 2010

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Abstract. Magnetohydrodynamic (MHD) models of the global magnetosphere are very good research tools for investigating the topology and dynamics of the near-Earth space environment. While these models have obvious limitations in regions that are not well described by the MHD equations, they can typically be used (or are used) to investigate the majority of magnetosphere. Often, a secondary consideration is overlooked by researchers when utilizing global models -the effects of solving the MHD equations on a grid, instead of analytically. Any discretization unavoidably introduces numerical artifacts that affect the solution to various degrees. This paper investigates some of the consequences of the numerical schemes and grids that are used to solve the MHD equations in the global magnetosphere. Specifically, the University of Michigan's MHD code is used to investigate the role of grid resolution, numerical schemes, limiters, inner magnetospheric density boundary conditions, and the artificial lowering of the speed of light on the strength of the ionospheric cross polar cap potential and the build up of the ring current in the inner magnetosphere. It is concluded that even with a very good solver and the highest affordable grid resolution, the inner magnetosphere is not grid converged. Artificially reducing the speed of light reduces the numerical diffusion that helps to achieve better agreement with data. It is further concluded that many numerical effects work nonlinearly to complicate the interpretation of the physics within the magnetosphere, and so simulation results should be scrutinized very carefully before a physical interpretation of the results is made. Our conclusions are not limited to the Michigan MHD code, but apply to all MHD models due to the limitations of computational resources.

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Section: Numerical Flux Functionssupporting

confidence: 79%

Numerical considerations in simulating the global magnetosphere

et al. 2010

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“…This list of reconnection encounters, covering [2001][2002][2003][2004][2005][2006], was compiled by visual inspection of the data and is a continuation of those presented in Borg (2006). The list also includes those reported by Eastwood et al (2010) (Nagai, 2006).…”

Section: Datamentioning

confidence: 99%

Electron pitch angle distribution during magnetic reconnection diffusion region observations in the Earth's magnetotail

2012

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Abstract. The Earth's magnetosphere provides an excellent laboratory for magnetic reconnection research. In particular, the magnetotail current sheet that is formed between the interface of the similar Northern and Southern Hemispheres of the magnetotail provides a relatively stable symmetric reconnection configuration that can be used to study basic aspects of the reconnection process. Of particular importance is the manner in which electrons are processed by the reconnection. Simulations and satellite data analyses of the ion diffusion region have suggested that the fluxes of electrons in the inflow regions of reconnection are greater in the directions parallel and anti-parallel to the magnetic field (field-aligned) whereas the electron flux in the outflow region is distributed more isotropically. However, this has only been studied experimentally on a case-by-case basis. In this paper, we investigate this claim by analyzing the degree of bulk electron field alignment in the outflow and inflow regions during encounters of the magnetic reconnection ion diffusion region by the Cluster spacecraft in the years [2001][2002][2003][2004][2005][2006]. We demonstrate that while the median electron flux in the inflow region is indeed more field aligned than in the outflow region during some ion diffusion region encounters, the variation of the signature across events is so large that it cannot be said to be a general feature of magnetic reconnection in the Earth's magnetotail.

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“…Tail reconnection is recognized as the main energy source of substorms (Baker et al, 1996): The substorm sequence commences with a growth phase, during which magnetic flux is added to the tail and the near-Earth current sheet grows thinner. At substorm onset a neutral line forms in the tail, most frequently at a radial distance of 20-30 R E but sometimes also closer to the Earth (Nagai, 2006, and references therein). Global MHD simulations support the view that the reconnection site acts as a centre of Poynting flux focussing, where the incoming electromagnetic energy is partly converted to kinetic and thermal energy of the plasma and where some of it is diverted earthward (Laitinen et al, 2005).…”

Section: Introductionmentioning

confidence: 97%

Global and local disturbances in the magnetotail during reconnection

et al. 2007

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Abstract. We examine Cluster observations of a reconnection event at x GSM =−15.7 R E in the magnetotail on 11 October 2001, when Cluster recorded the current sheet for an extended period including the entire duration of the reconnection event. The onset of reconnection is associated with a sudden orientation change of the ambient magnetic field, which is also observed simultaneously by Goes-8 at geostationary orbit. Current sheet oscillations are observed both before reconnection and during it. The speed of the flapping motions is found to increase when the current sheet undergoes the transition from quiet to active state, as suggested by an earlier statistical result and now confirmed within one single event. Within the diffusion region both the tailward and earthward parts of the quadrupolar magnetic Hall structure are recorded as an x-line passes Cluster. We report the first observations of the Hall structure conforming to the kinks in the current sheet. This results in relatively strong fluctuations in B z , which are shown to be the Hall signature tilted in the yz plane with the current sheet.

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Location of Magnetic Reconnection in the Magnetotail

Cited by 25 publications

References 40 publications

Numerical considerations in simulating the global magnetosphere

Numerical considerations in simulating the global magnetosphere

Electron pitch angle distribution during magnetic reconnection diffusion region observations in the Earth's magnetotail

Global and local disturbances in the magnetotail during reconnection

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