Global configuration of the magnetotail current sheet as derived from Geotail, Wind, IMP 8 and ISEE 1/2 data

Tsyganenko, N. A.; Karlsson, Sandra; Kokubun, S.; Yamamoto, T.; Lazarus, A. J.; Ogilvie, K. W.; Russell, C. T.; Slavin, J. A.

doi:10.1029/97ja03621

Cited by 56 publications

(57 citation statements)

References 34 publications

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“…Observations (Tsyganenko, 1989) and MHD simulations (Walker et al, 1999;Kullen and Janhunen, 2004) show that during north-duskward IMF the plasma sheet is strongly twisted, leading to an expansion of the duskside plasma sheet to very high latitudes. Mapping the plasma sheet boundary to the northern ionosphere leads to a poleward displacement of the duskside closed field line boundary (Kullen and Blomberg, 1996).…”

Section: Imf Influencementioning

confidence: 99%

An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

Rosenqvist

Kullén²,

Buchert³

2007

Ann. Geophys.

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Abstract. The shock arrival of an Interplanetary Coronal Mass Ejection (ICME) at ∼09:50 UT on 22 November 1997 resulted in the development of an intense (D st <−100 nT) geomagnetic storm at Earth. In the early, quiet phase of the storm, in the sheath region of the ICME, an unusual large spiral structure (diameter of ∼1000 km) was observed at very high latitudes by the Polar UVI instrument. The evolution of this structure started as a polewardly displaced auroral bulge which further developed into the spiral structure spreading across a large part of the polar cap. This study attempts to examine the cause of the chain of events that resulted in the giant auroral spiral. During this period the interplanetary magnetic field (IMF) was dominantly northward (B z >25 nT) with a strong duskward component (B y >15 nT) resulting in a highly twisted tail plasma sheet. Geotail was located at the equatorial dawnside magnetotail flank and observed accelerated plasma flows exceeding the solar wind bulk velocity by almost 60%. These flows are observed on the magnetosheath side of the magnetopause and the acceleration mechanism is proposed to be typical for strongly northward IMF. Identified candidates to the cause of the spiral structure include a B y induced twisted magnetotail configuration, the development of magnetopause surface waves due to the enhanced pressure related to the accelerated magnetosheath flows aswell as the formation of additional magnetopause deformations due to external solar wind pressure changes. The uniqeness of the event indicate that most probably a combination of the above effects resulted in a very extreme tail topology. However, the data coverage is insufficient to fully investigate the physical mechanism behind the observations.

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Section: Imf Influencementioning

confidence: 99%

An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

Rosenqvist

Kullén²,

Buchert³

2007

Ann. Geophys.

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“…Figures 1b-1d indicate the location of the Geotail spacecraft in the GSM coordinate system. direction of the current sheet normal, we first convert to GSW (Geocentric Solar Wind) coordinates (x opposite to solar wind velocity, dipole in the xz plane) [Hones et al, 1986;Tsyganenko et al, 1998]. We then use the formulae of Tsyganenko and Fairfield [2004] to estimate the shape of the current sheet, for calculation of the normal.…”

Section: Geotail Magnetic Fieldsmentioning

confidence: 99%

Rice Convection Model simulation of the substorm‐associated injection of an observed bubble into the inner magnetosphere: 1. Magnetic field and other inputs

et al. 2009

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[1] The objective of this work is a realistic Rice Convection Model (RCM) simulation of a modest substorm that occurred on 22 July 1998 and was observed by the Geotail spacecraft in the inner plasma sheet. It represents the first time the RCM has been used for detailed modeling of an inner magnetospheric event using data from a spacecraft in the inner plasma sheet beyond geosynchronous orbit to drive the model's time-dependent boundary conditions. Since this represents a substantial departure from past practice, we present, in this paper, a detailed account of how model inputs are determined. An accompanying paper presents results and interpretations. Model inputs are adjusted to achieve approximate consistency between RCM-computed values and measurements by Geotail, which was within the RCM modeling region near X GSM = À9 R E , Y GSM = 0. To represent the magnetic field in the growth phase, we utilize a Tsyganenko (1989) statistical magnetic field model, adjusted to agree with Geotail-measured pressure and magnetic field in a new way using analytic solutions to the linear Grad-Shafranov equation. The magnetic field during the expansion phase is represented by adding a substorm current wedge using formulas developed by Tsyganenko. Induction electric fields play a central role in these simulations, because they are large in the vicinity of the substorm injection region. We provide a detailed description of how induction electric fields are included in the RCM as well as a prescription of the electromagnetic gauge condition used in the code.

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“…As will be shown in section 3.1, that assumption is generally not true. Besides that, no dependence of the tail current position on the IMF By was assumed in previous models, even though the related "twisting" effect was predicted [Russell, 1972] and was found to be quite significant even at relatively close geocentric distances [Sibeck et al, 1985[Sibeck et al, , 1986aTsyganenko, 1990;Tsyganenko et al, 1998]. …”

Section: Introductionmentioning

confidence: 99%

Modeling of twisted/warped magnetospheric configurations using the general deformation method

Tsyganenko¹

1998

J. Geophys. Res.

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122

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Furthermore, the method makes it possible to add flexibility to the model magnetopause, so that the effects of the dipole tilt and of the IMF upon its shape can be reproduced. In particular, the transformation with a radially dependent rotation of the X and Z axes, while providing the desired tilt-related bending of the cross-tail current sheet, can also deform the magnetopause and reproduce its tilt-related asymmetry, indicated by observations and reported here for the first time. The deformation technique also allows algorithms that are more compact and faster than the currently used ones. Because of the general nature of the proposed approach it should be possible to extend it to the modeling of other (e.g., Jovian) planetary magnetospheres.

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Global configuration of the magnetotail current sheet as derived from Geotail, Wind, IMP 8 and ISEE 1/2 data

Cited by 56 publications

References 34 publications

An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

An unusual giant spiral arc in the polar cap region during the northward phase of a Coronal Mass Ejection

Rice Convection Model simulation of the substorm‐associated injection of an observed bubble into the inner magnetosphere: 1. Magnetic field and other inputs

Modeling of twisted/warped magnetospheric configurations using the general deformation method

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