Structure and dynamics of magnetic reconnection for substorm onsets with Geotail observations

Nagai, T.; Fujimoto, M.; Saito, Y.; Machida, S.; Terasawa, T.; Nakamura, R.; Yamamoto, T.; Mukai, T.; Nishida, A.; Kokubun, S.

doi:10.1029/97ja02190

Cited by 525 publications

(510 citation statements)

References 53 publications

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“…[39] Altogether, we could determine the location of the reconnection site being at about À16 R E (À17.5 R E ) for the event at 0200 UT (0815 UT), which is closer to Earth than the statistical studies of Nagai et al [1998] and Baumjohann et al [1999] suggested. However, these studies used Geotail data obtained during the solar minimum.…”

Section: Summary and Discussionmentioning

confidence: 99%

First application of a Petschek‐type reconnection model with time‐varying reconnection rate to THEMIS observations

et al. 2009

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[1] We present a method to determine the location of the reconnection site and the amount of reconnected magnetic flux out of an analytical time-dependent reconnection model and apply this method to disturbances observed on 2 February 2008 at about 0200 and 0815 UT by THEMIS B (P1). During these events, P1 detected two tailward propagating traveling compression regions, associated with typical variations in B z and B x . We find the reconnection site to be located at about À16 R E for the event at 0200 UT and À17.5 R E for the event at 0815 UT. These locations are consistent with simple timing considerations with respect to disturbances detected by the inner THEMIS spacecraft. The amount of reconnected flux in our 2-D model can be found to be in the order of 10 8 nT m for both events. The calculations for the reconnection site's location are done by using two approaches, i.e., by using the B z and the B x signals, yielding consistent results. The reconnected flux can be determined using B z and v z . Also, these results are in good agreement. A comparison between the disturbances detected by P1 and the modeled variations shows that our model describes disturbances in the magnetic field and the background plasma very well.

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Section: Summary and Discussionmentioning

confidence: 99%

First application of a Petschek‐type reconnection model with time‐varying reconnection rate to THEMIS observations

et al. 2009

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“…), which are also characterized by enhanced magnetic reconnection and BBF activity (Angelopoulos et al, 1994;Nagai et al, 1998;Baumjohann et al, 1999). Observation of some fraction of crossings during very quiet (AE) periods does not contradict this association, since both localized isolated fast streams and magnetic reconnection events are also known to appear under magnetically quiet conditions (Baumjohann et al, 1990;Angelopoulos et al, 1994;Nagai et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Survey of large-amplitude flapping motions in the midtail current sheet

et al. 2006

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Abstract. We surveyed fast current sheet crossings (flapping motions) over the distance range 10-30 R E in the magnetotail covered by the Geotail spacecraft. Since the local tilts of these dynamic sheets are large and variable in these events, we compare three different methods of evaluating current sheet normals using 4-s/c Cluster data and define the success criteria for the single-spacecraft-based method (MVA) to obtain the reliable results. Then, after identifying more than ∼ 1100 fast CS crossings over a 3-year period of Geotail observations in 1997-1999, we address their parameters, spatial distribution and activity dependence. We confirm that over the entire distance covered and LT bins, fast crossings have considerable tilts in the YZ plane (from estimated MVA normals) which show a preferential appearance of one (YZ kinklike) mode that is responsible for these severe current sheet perturbations. Their occurrence is highly inhomogeneous; it sharply increases with radial distance and has a peak in the tail center (with some duskward shift), resembling the occurrence of the BBFs, although there is no one-to-one local correspondence between these two phenomena. The crossing durations typically spread around 1 min and decrease significantly where the high-speed flows are registered. Based on an AE index superposed epoch study, the flapping motions prefer to appear during the substorm expansion phase, although a considerable number of events without any electrojet and auroral activity were also observed. We also present statistical distributions of other parameters and briefly discuss what could be possible mechanisms to generate the flapping motions.

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“…Nagai et al, 1998]. However, the reader should keep in mind that this 11/13/03 event happened in the dusk flank, plus that the X-line is possibly moving, so this calculation must be viewed as a rough first order check.…”

Section: Our Model To Explain the Pad Evolutionmentioning

confidence: 99%

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

Fritz

Larvaud

et al. 2006

Geophysical Research Letters

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The Cluster satellites observed a distinct pattern in the evolution of energetic electron pitch angle distributions on November 13, 2003, in the mid‐tail (radius >10RE) associated with intensifications of these electron fluxes that accompanied an observed local dipolarization of the magnetic field. The intensity of electrons (20–200 keV) were first observed to increase for perpendicular pitch angles (pancake distribution), then evolve into isotropic distributions, then further evolve into mixed distributions ‐ a combination of perpendicularly peaked distributions and beamlike distributions (cigar distribution), and at the end of each of three episodes always evolved into a beamlike or field‐aligned distribution. This evolution pattern seen at a relative fixed observing (satellite) location usually developed within the locally observed dipolarization time scale. We have interpreted this pattern to indicate that electrons were coming from different regions along the magnetotail and have gotten accelerated differently. This has led us to suggest and present a model in which Fermi acceleration dominates for electrons that are accelerated from the reconnection region, while betatron acceleration dominates for electrons that are accelerated from the mid‐tail region that is very close to the satellite location.

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Structure and dynamics of magnetic reconnection for substorm onsets with Geotail observations

Cited by 525 publications

References 53 publications

First application of a Petschek‐type reconnection model with time‐varying reconnection rate to THEMIS observations

First application of a Petschek‐type reconnection model with time‐varying reconnection rate to THEMIS observations

Survey of large-amplitude flapping motions in the midtail current sheet

Substorm associated magnetotail energetic electrons pitch angle evolutions and flow reversals: Cluster observation

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