Magnetic flux transfer at the magnetopause based on single X line bursty reconnection

Scholer, M.

doi:10.1029/gl015i004p00291

Cited by 299 publications

(223 citation statements)

References 16 publications

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“…This model is similar to the flux rope model in many ways, but it explains the bulge as the effect of a pulse of enhanced reconnection rate at an X line whose length is not specified. Such bulges can be reproduced in MHD simulations [Scholer, 1988a[Scholer, , b, 1989Ma et al, 1994] Figure 2a. Unless the flow streamlines tangential to the magnetopause change, the satellite will see only those field lines that were reconnected at one point of the X line, and thus there is no information about the extent of the event or of the X line.…”

Section: Two-dimensional (2-d) Reconnection Pulse Modelmentioning

confidence: 99%

On the cause of a magnetospheric flux transfer event

Lockwood¹,

Hapgood²

1998

J. Geophys. Res.

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Abstract. We present a detailed investigation of a magnetospheric flux transfer event (FFE) seen by the Active Magnetospheric Tracer Explorer (AMPTE) UKS and IRM satellites around 1046 UT on October 28, 1984. This event has been discussed many times previously in the literature and has been cited as support for a variety of theories of FTE formation. We make use of a model developed to reproduce ion precipitations seen in the cusp ionosphere. The analysis confirms that the FTE is well explained as a brief excursion into an open low-latitude boundary layer (LLBL), as predicted by two theories of magnetospheric FTEs, namely, that they are bulges in the open LLBL due to reconnection rate enhancements or that they are indentations of the magnetopause by magnetosheath pressure increases (but in the presence of ongoing steady reconnection). The indentation of the inner edge of the open LLBL that these two models seek to explain is found to be shallow for this event. The ion model reproduces the continuous evolution of the ion distribution function between the sheath-like population at the event center and the surrounding magnetospheric populations; it also provides an explanation of the high-pressure core of the event as comprising field lines that were reconnected considerably earlier than those that are draped over it to give the event boundary layer. The magnetopause transition parameter is used to isolate a field rotation on the boundaries of the core, which is subjected to the tangential stress balance test. The test identifies this to be a convecting structure, which is neither a rotational discontinuity (Pal)) nor a contact discontinuity, but could possibly be a slow shock. In addition, evidence for ion reflection off a weak RD on the magnetospheric side of this structure is found. The event structure is consistent in many ways with features predicted for the open LLBL by analytic MHD theories and by MHD and hybrid simulations. The de HoffinanTeller velocity of the structure is significantly different from that of the magnetosheath flow, indicating that it is not an indentation caused by a high-pressure pulse in the sheath but is consistent with the motion of newly opened field lines (different from the sheath flow because of the magnetic tension force) deduced from the best fit to the ion data. However, we cannot here role out the possibility that the sheath flow pattern has changed in the long interval between the two satellites observing the FTE and subsequently emerging into the magnetosheath; thus this test is not conclusive in this particular case. Analysis of the fitted elapsed time since reconnection shows that the core of the event was reconnected in one pulse and the event boundary layer was reconnected in a subsequent pulse. Between these two pulses is a period of very low (but nonzero) reconnection rate, which lasts about 14 rains. Thus the analysis supports, but does not definitively verify, the concept that the FTE is a partial passage into an open LLBL caused by a traveling bulge in that layer pr...

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Section: Two-dimensional (2-d) Reconnection Pulse Modelmentioning

confidence: 99%

On the cause of a magnetospheric flux transfer event

Lockwood¹,

Hapgood²

1998

J. Geophys. Res.

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“…FTEs created by reconnection occurring simultaneously at multiple dayside X-lines are identified by their flux rope structure [Lee and Fu, 1985]. FTEs not possessing flux rope topology may be produced by short-duration pulses of reconnection [Southwood et al, 1988;Scholer, 1988]. They are identified primarily by the characteristic manner in which magnetosheath and magnetospheric magnetic fields drape about these flux tubes as they move tailward.…”

Section: Introductionmentioning

confidence: 99%

MESSENGER observations of large flux transfer events at Mercury

Slavin

Lepping

et al. 2010

Geophysical Research Letters

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[1] Six flux transfer events (FTEs) were encountered during MESSENGER's first two flybys of Mercury (M1 and M2). For M1 the interplanetary magnetic field (IMF) was predominantly northward and four FTEs with durations of 1 to 6 s were observed in the magnetosheath following southward IMF turnings. The IMF was steadily southward during M2, and an FTE 4 s in duration was observed just inside the dawn magnetopause followed $32 s later by a 7-s FTE in the magnetosheath. Flux rope models were fit to the magnetic field data to determine FTE dimensions and flux content. The largest FTE observed by MESSENGER had a diameter of $1 R M (where R M is Mercury's radius), and its open magnetic field increased the fraction of the surface exposed to the solar wind by 10-20 percent and contributed up to $30 kV to the cross-magnetospheric electric potential.

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“…Southwood et al (1988) and Scholer (1988) independently proposed a model based on a single X-line, where the magnetopause boundary layer thickens and then thins as a result of a variation in the reconnection rate, producing a bulge which propagates under the same magnetosheath flow and j ×B effects. This two dimensional model does not produce a tube of reconnected flux, but can extend a considerable distance along the magnetopause.…”

Section: Introductionmentioning

confidence: 99%

Motion of flux transfer events: a test of the Cooling model

et al. 2007

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Abstract. The simple model of reconnected field line motion developed by Cooling et al. (2001) has been used in several recent case studies to explain the motion of flux transfer events across the magnetopause. We examine 213 FTEs observed by all four Cluster spacecraft under a variety of IMF conditions between November 2002 and June 2003, when the spacecraft tetrahedron separation was ∼5000 km. Observed velocities were calculated from multi-spacecraft timing analysis, and compared with the velocities predicted by the Cooling model in order to check the validity of the model. After excluding three categories of FTEs (events with poorly defined velocities, a significant velocity component out of the magnetopause surface, or a scale size of less than 5000 km), we were left with a sample of 118 events. 78% of these events were consistent in both direction of motion and speed with one of the two model de Hoffmann-Teller (dHT) velocities calculated from the Cooling model (to within 30 • and a factor of two in the speed). We also examined the plasma signatures of several magnetosheath FTEs; the electron signatures confirm the hemisphere of connection indicated by the model in most cases. This indicates that although the model is a simple one, it is a useful tool for identifying the source regions of FTEs.

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Magnetic flux transfer at the magnetopause based on single X line bursty reconnection

Cited by 299 publications

References 16 publications

On the cause of a magnetospheric flux transfer event

On the cause of a magnetospheric flux transfer event

MESSENGER observations of large flux transfer events at Mercury

Motion of flux transfer events: a test of the Cooling model

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