Journal ArticleDOI
Current disruption in the Earth's magnetosphere: Observations and models
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In this paper, the cross-tail current sheet shows a rapid growth in the current density, a large upsurge in the duskward ion bulk speed to nearly the ion thermal speed, an increase in the plasma pressure and its isotropy, a rise in the ion beta, and a decrease in the thickness of the current sheet to a length scale comparable to the thermal ion gyroradius.Abstract:
Observations and models of current disruption in the Earth's magnetosphere are briefly reviewed. At the approach of current disruption onset, the cross-tail current sheet shows a rapid growth in the current density, a large upsurge in the duskward ion bulk speed to nearly the ion thermal speed, an increase in the plasma pressure and its isotropy, a rise in the plasma beta, and a decrease in the current sheet thickness to a length scale comparable to the thermal ion gyroradius. During current disruption, there are (1) large changes in the local magnetic and electric fields, (2) significant magnetic and electric fluctuations over a broad frequency range, (3) magnetic field-aligned counterstreaming electron beams, (4) ion energization perpendicular to the magnetic field, and (5) reduction in the cross-tail current by an amount similar to that built up during the growth phase. Observations further indicate that regions of local reversal of the north-south magnetic field component are not necessarily sites of intense particle energization. Remote sensing of disruption activities shows that at least some current disruptions are not caused by a disturbance propagating earthward from the tail beyond 10 RE downstream. The timescale involved is comparable to or shorter than the ion gyroperiod. Current disruption thus has spatial and temporal scales outside the MHD regime. Several models for current disruption are briefly discussed. Two roles are considered for the cross-field current instability proposed for current disruption. It can provide anomalous resistivity for magnetic reconnection as advocated by the traditional viewpoint or act singly to instigate global changes of the magnetosphere during the initial substorrn expansion phase. The latter role is elaborated by showing that the instability may modify significantly the local current density and any such process will alter the force equilibrium in the current sheet and give rise to an efficient plasma and energy transport on a global scale. Furthermore, such a process can generate field-aligned current with intensity comparable to those associated with an auroral breakup arc at substorrn expansion onset. This scenario leads to a new emphasis that in addition to magnetic reconnection, rapid conversion of magnetic energy into particle energy in magnetotail systems may take place without a magnetic X line or separatrix playing the key role in energy conversion.read more
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The THEMIS Mission
TL;DR: The Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission is the fifth NASA Medium-class Explorer (MIDEX), launched on February 17, 2007 to determine the trigger and large-scale evolution of substorms as discussed by the authors.
Journal ArticleDOI
Neutral line model of substorms: Past results and present view
Daniel N. Baker,Tuija Pulkkinen,Vassilis Angelopoulos,Wolfgang Baumjohann,Robert L. McPherron +4 more
TL;DR: In this article, the authors reviewed the NENL model of magnetospheric substorms, including the role of coupling with the solar wind and interplanetary magnetic field, the growth phase sequence, the expansion phase (and onset), and the recovery phase.
Journal ArticleDOI
Tail reconnection triggering substorm onset.
Vassilis Angelopoulos,James P. McFadden,Davin Larson,C. W. Carlson,Stephen B. Mende,Harald U. Frey,Tai Phan,David G. Sibeck,Karl-Heinz Glassmeier,Uli Auster,Eric Donovan,Ian R. Mann,I. Jonathan Rae,Christopher T. Russell,Andrei Runov,Xu-Zhi Zhou,Larry Kepko +16 more
TL;DR: Results demonstrate that substorms are likely initiated by tail reconnection, and are reported on simultaneous measurements in the magnetotail at multiple distances, at the time of substorm onset.
Journal ArticleDOI
The Search-Coil Magnetometer for MMS
O. Le Contel,Paul Leroy,Alain Roux,Christophe Coillot,D. Alison,A. Bouabdellah,L. Mirioni,L. Meslier,A. Galic,M. C. Vassal,Roy B. Torbert,J. Needell,D. Rau,I. Dors,Robert E. Ergun,J. Westfall,D. Summers,J. Wallace,Werner Magnes,Aris Valavanoglou,Göran F. Olsson,M. Chutter,Joseph Macri,S. Myers,S. Turco,J. Nolin,D. Bodet,K. M. Rowe,M. Tanguy,B. de la Porte +29 more
TL;DR: The tri-axial search-coil magnetometer (SCM) belongs to the FIELDS instrumentation suite on the Magnetospheric Multiscale (MMS) mission as discussed by the authors.
Journal ArticleDOI
Self-organized criticality, multi-fractal spectra, sporadic localized reconnections and intermittent turbulence in the magnetotail
TL;DR: In this article, some basic physical concepts and mathematical techniques (such as the dynamic merging of coherent structures, nonclassical nonlinear instability, path integrals, the theory of the renormalization-group, low-dimensional chaos, self-similarity and scaling, fractals, coarse-grained helicity and symmet...) are described.
References
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Journal ArticleDOI
The development of the auroral substorm.
TL;DR: In this paper, a working model of simultaneous auroral activity over the entire polar region is presented in terms of the auroral substorm, which has two characteristic phases, an expansive phase and a recovery phase.
Journal ArticleDOI
Satellite studies of magnetospheric substorms on August 15, 1968: 9. Phenomenological model for substorms
TL;DR: In this paper, the authors present a phenomenological model of the magnetospheric substorm sequence, which can be divided into three main phases: the growth phase, the expansion phase, and the recovery phase.
Journal Article
Satellite studies of magnetospheric substorms on August 15, 1968. IX - Phenomenological model for substorms.
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Journal ArticleDOI
Statistical characteristics of bursty bulk flow events
Vassilis Angelopoulos,Charles F. Kennel,Ferdinand V. Coroniti,R. Pellat,Margaret G. Kivelson,Raymond J. Walker,Christopher T. Russell,Wolfgang Baumjohann,W. C. Feldman,J. T. Gosling +9 more
TL;DR: In this paper, the statistical properties of bursty bulk flow events (BBFs) in the inner plasma sheet (IPS) were analyzed using data from active magnetospheric particle tracer Explorer/Ion Release Module (AMPTE/IRM) and International Sun-Earth Explorer 2 (ISEE 2) satellites.
Journal ArticleDOI
Regular and chaotic charged particle motion in magnetotaillike field reversals: 1. Basic theory of trapped motion
Jörg Büchner,Lev Zelenyi +1 more
TL;DR: In this paper, the authors give a systematic theoretical analysis of trapped nonadiabatic charged particle motion in two-dimensional taillike magnetic field reversals and derive the related pitch angle diffusion coefficient which describes statistically the particle behavior in the limit κ → 1.