Analyses on the geometrical structure of magnetic field in the current sheet based on cluster measurements

Shen, C.; Li, Xin; Dunlop, M. W.; Liu, Z. X.; Balogh, A.; Baker, D. N.; Hapgood, M. A.; Wang, X.

doi:10.1029/2002ja009612

Cited by 113 publications

(225 citation statements)

References 37 publications

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“…Using this, the local geometrical properties of curvature, curvature radius, and the binormal of the magnetic field lines (MFL) can be obtained. In the work of Shen et al [2003], however, the geometrical features of MFLs described only the one-dimensional rotation of magnetic field. Until now, it was not clear how to obtain the complete threedimensional rotation features of magnetic field from multiple satellite measurements.…”

Section: Introductionmentioning

confidence: 99%

“…Taking advantage of the four-point magnetic field measurements [Balogh et al, 2001] of Cluster, the curvature analysis approach has been developed [Shen et al, 2003]. Using this, the local geometrical properties of curvature, curvature radius, and the binormal of the magnetic field lines (MFL) can be obtained.…”

Section: Introductionmentioning

confidence: 99%

“…[4] In this work, we seek to update the original analysis of field curvature [Shen et al, 2003] in a more consistent way and develop the method more explicitly to determine the three-dimensional rotation features of the magnetic field, applying it to particular structures in the magnetosphere. Some authors have also developed four-point analysis methods to determine the normal and motion of a one-dimensional boundary (see ISSI technique book, e.g., Dunlop et al [1998]).…”

Section: Introductionmentioning

confidence: 99%

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Magnetic field rotation analysis and the applications

et al. 2007

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[1] An analysis technique, termed MRA (magnetic rotation analysis), has been designed to probe three-dimensional magnetic field topology. It is based on estimating the gradient tensor of four-point measurements of the magnetic field which have been taken by the Cluster mission. The method first constructs the symmetrical magnetic rotation tensor and in general terms deduces the rotation rate of magnetic field along one arbitrary direction. In particular, the maximum, medium, and minimum magnetic rotation rates along corresponding characteristic directions of a magnetic structure can be obtained. The value of the curvature of a magnetic field line, for example, is given by the magnetic rotation rate along the magnetic unit vector and its corresponding radius of curvature is readily obtained. MRA has been applied here to analyze the geometrical structure of two distinct magnetospheric structures, i.e., the tail current sheet and the tail flux rope. The normal of the current sheet is the direction at which the magnetic field has the largest rotation rate. The half thickness of the one-dimensional neutral sheet can also be determined from the reciprocal of the maximum magnetic rotation rate. The advantage of the MRA method is that not only it can determine the orientation but also the internal geometrical configuration and spatial scale of the magnetic structures. A key feature of the MRA method is that it provides the detailed picture of the magnetic rotation point by point through any crossing of the current sheet. As a result, the thickness of the neutral sheet (NS) can be explicitly demonstrated to vary with time, as indicated in one case study, where the NS becomes thicker after the onset of a substorm. MRA has also been applied here to analyze the detailed features of magnetic field variations inside of a flux rope. The principal axis of the flux rope is the direction at which the magnetic field rotates at the least rate. The magnetic scale of the flux rope can also be determined (about 1R E in the case chosen). It is also found that there are both frontside-backside and dawn-dusk asymmetries for the flux rope under study.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic field rotation analysis and the applications

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“…The neutral sheet is originally defined as a region where the tail's magnetic field reverses its direction and has a very weak magnitude (Ness, 1965); it has also been defined by some researchers as the midsurface of the nightside plasma sheet (Dandouras, 1988), or as a region within the current sheet where the component in the Sun-Earth direction of the magnetic field is less than the northward component (Shen et al, 2003). Many researchers have simply defined the neutral sheet as a curved surface where the X component of the geomagnetic field changes its direction, which characterizes the properties of the plasma sheet, from sunward to antisunward and vice versa (Speiser and Ness, 1967;Dandouras, 1988;Xu et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

et al. 2005

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Abstract. By using the data of two spacecraft, TC-1 and ACE (Advanced Composition Explorer), a statistical study on the correlations between plasma sheet and solar wind has been carried out. The results obtained show that the plasma sheet at geocentric distances of about 9∼13.4 Re has an apparent driving relationship with the solar wind. It is found that (1) there is a positive correlation between the duskward component of the interplanetary magnetic field (IMF) and the duskward component of the geomagnetic field in the plasma sheet, with a proportionality constant of about 1.09. It indicates that the duskward component of the IMF can effectively penetrate into the near-Earth plasma sheet, and can be amplified by sunward convection in the corresponding region at geocentric distances of about 9∼13.4 Re; (2) the increase in the density or the dynamic pressure of the solar wind will generally lead to the increase in the density of the plasma sheet; (3) the ion thermal pressure in the near-Earth plasma sheet is significantly controlled by the dynamic pressure of solar wind; (4) under the northward IMF condition, the ion temperature and ion thermal pressure in the plasma sheet decrease as the solar wind speed increases. This feature indicates that plasmas in the near-Earth plasma sheet can come from the magnetosheath through the LLBL. Northward IMF is one important condition for the transport of the cold plasmas of the magnetosheath into the plasma sheet through the LLBL, and fast solar wind will enhance such a transport process.

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“…[4] Cluster observations of the near-Earth magnetotail demonstrate the formation of thin current sheets with a thickness of an ion Larmor radius scale during active periods [Shen et al, 2003;Runov et al, 2003] Marcucci et al [2004] reports on energetic O+ ions emerging from the dayside magnetopause, which form highly anisotropic distributions in the magnetosheath. This study presents the results of a test particle simulation that show that the highly non-gyrotropic distributions can come from remote sensing of a thin current sheet.…”

Section: Introductionmentioning

confidence: 99%

Modeling of remote sensing of thin current sheet

Lee

Wilber

Parks

et al. 2004

Geophysical Research Letters

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[1] Cluster encountered a thin current sheet in the magnetotail during a substorm on Oct. 1, 2001. The phase space distributions observed by Cluster CIS showed large gradients in the phase space with ions existing only in one hemisphere of the phase space. It has been suggested that these non-gyrotropic distributions come from remote sensing of a thin current sheet by spacecrafts outside the current sheet. We present the results of a test particle simulation that confirm non-gyrotropic distributions can arise from remote sensing of a thin current sheet. These nongyrotropic distributions can yield large velocity moments even when the plasma is stationary. The large velocity moments are not in the convective flow direction that would be normal to the current sheet. Instead they are along the n Â B direction where n is normal to the boundary. These modeling results reinforce the importance of examining full particle distributions when studying plasma sheet dynamics.

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Analyses on the geometrical structure of magnetic field in the current sheet based on cluster measurements

Cited by 113 publications

References 37 publications

Magnetic field rotation analysis and the applications

Magnetic field rotation analysis and the applications

A statistical study on the correlations between plasma sheet and solar wind based on DSP explorations

Modeling of remote sensing of thin current sheet

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