Reconstruction of two‐dimensional coherent structures in ideal and resistive Hall MHD: The theory

Sonnerup, B. U. Ö.; Teh, W.‐L.

doi:10.1029/2008ja013897

Cited by 19 publications

(22 citation statements)

References 34 publications

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“…These techniques can be categorized into three types: (1) reconstruction of 2D structures based on the Grad-Shafranov (GS) or GS-like equation , (2) 2008; Sonnerup and Teh, 2009), and (3) reconstruction of slow time evolution of quasi-static 2D structures (Sonnerup and Hasegawa, 2010). Most recently, it has also been shown that reconstruction of 3D structures is in principle possible if the spatial gradient in certain direction(s) can be estimated from closely separated two or more spacecraft measurements (Sonnerup and Hasegawa, 2011).…”

Section: Reconstruction Methodsmentioning

confidence: 99%

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: Reconstruction Methodsmentioning

confidence: 99%

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Hasegawa¹

2012

Monogr. Environ. Earth Planets

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“…Sonnerup et al [, hereafter referred to as SEA16] have recently developed a data analysis tool for the reconstruction of steady, two‐dimensional (2‐D) magnetic field and electron flow in and around the EDR of antiparallel reconnection. The method is based on electron magnetohydrodynamic (EMHD) equations and is an extension of the MHD‐ and Hall MHD‐based reconstruction techniques, an overview of which was given by Sonnerup et al [] and Sonnerup and Teh []. They help us to understand what type of structure an observing spacecraft encountered and at what time, by providing 2‐D maps of the magnetic and/or velocity fields.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of the electron diffusion region observed by the Magnetospheric Multiscale spacecraft: First results

Hasegawa

Sonnerup

Denton

et al. 2017

Geophysical Research Letters

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We present first results of the reconstruction of the electron diffusion region (EDR) based on a two‐dimensional, incompressible, and inertialess version of the electron magnetohydrodynamics equations. The method is applied to 30 ms resolution magnetic field, and electron moments data taken when the Magnetospheric Multiscale (MMS) spacecraft observed an EDR of near‐antiparallel magnetopause reconnection on 16 October 2015. An X‐type magnetic field configuration and quadrupolar Hall fields, consistent with the electron inflow and outflow, are successfully recovered. While MMS encountered a region of significant energy dissipation on the magnetospheric side of the sub‐ion‐scale current sheet, the reconstructions show that the MMS tetrahedron missed the X line by a distance of a few kilometers (~2 electron inertial lengths). The estimated reconnection electric field is 0.42–0.98 mV/m, equivalent to the dimensionless reconnection rate of 0.11–0.25. Signatures of three‐dimensional structures and/or time‐dependent processes are also identified.

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“…Figure 3b shows the Cluster observations of the magnetic and electric fields and the ion velocity, in the LMN coordinates, for the first observed flux rope. This event had been studied previously by Eastwood et al [2007] for the Hall electromagnetic fields and by Teh et al [2011] for the Hall-MHD reconstruction technique [Sonnerup and Teh, 2009] . Interestingly, the other three spacecraft, which were separated in the GSM z axis from C3, did not see the flux rope within the positive Hall field region.…”

Section: Magnetotail Reconnection With a Weak Guide Fieldmentioning

confidence: 99%

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

et al. 2014

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The relationship between the core field and the interplanetary magnetic field (IMF) B y has been addressed by spacecraft observations in the magnetotail, but it is not yet fully clear since observations by Slavin et al. (2003) and Borg et al. (2012) show controversial results. In this study, we examine 13 flux ropes from the Cluster observations to show for the first time that the correlation between the core field B core and the IMF B y depends on the guide field B g . For large guide fields (> 20% of the reconnecting field), we show that the B core is found to correlate with the IMF B y . However, for weak guide fields (< 10% of the reconnecting field) we show that the core fields have either a positive or negative polarity, irrespective of the IMF B y . This result indicates that for weak guide field reconnection the core field generation of the magnetotail flux rope is not governed by the external IMF B y . We can explain the previous controversy in terms of the guide field dependency. We also confirm earlier suggestions that for weak guide field reconnection the flux ropes can have a significant core field whose polarity agrees with the ambient quadrupole Hall field. In addition, the Grad-Shafranov reconstruction results suggest that the axis of the flux rope may have been kinked. Our findings are crucial and can help advance theoretical simulations of the core field generation for weak guide reconnection. Discussions of the possible core field generation for weak guide field will be given in terms of 3-D reconnection.

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Reconstruction of two‐dimensional coherent structures in ideal and resistive Hall MHD: The theory

Cited by 19 publications

References 34 publications

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Reconstruction of the electron diffusion region observed by the Magnetospheric Multiscale spacecraft: First results

Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency

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Reconstruction of two‐dimensional coherent structures in ideal and resistive Hall MHD: The theory

Cited by 19 publications

References 34 publications

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Structure and Dynamics of the Magnetopause and Its Boundary Layers

Reconstruction of the electron diffusion region observed by the Magnetospheric Multiscale spacecraft: First results

Correlation of core field polarity of magnetotail flux ropes with the IMF By: Reconnection guide field dependency

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Correlation of core field polarity of magnetotail flux ropes with the IMF B_y: Reconnection guide field dependency