HR: 1340h
AN: SM33B-0454    [Abstracts]
TI: Plasmoids Observed in the Near-Earth Magnetotail at X=-7 Re
AU: * Miyashita, Y
EM: miyasita@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Aichi, 442-8507 Japan
AU: Ieda, A
EM: ieda@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Aichi, 442-8507 Japan
AU: Kamide, Y
EM: kamide@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Aichi, 442-8507 Japan
AU: Machida, S
EM: machida@kugi.kyoto-u.ac.jp
AF: Department of Geophysics, Kyoto University, Sakyo-ku, Kyoto, 606-8502 Japan
AU: Mukai, T
EM: mukai@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, 229-8510 Japan
AU: Saito, Y
EM: saito@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, 229-8510 Japan
AU: Liou, K
EM: Kan.Liou@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099 United States
AU: Meng, C
EM: ching.meng@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099 United States
AU: Parks, G K
EM: parks@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720 United States
AU: McEntire, R W
EM: richard.mcentire@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099 United States
AU: Nishitani, N
EM: nisitani@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Aichi, 442-8507 Japan
AU: Lester, M
EM: mle@ion.le.ac.uk
AF: Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH United Kingdom
AU: Sofko, G J
EM: George.Sofko@usask.ca
AF: Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, Saskatchewan, SK S7N 5E2 Canada
AU: Villain, J
EM: jvillain@cnrs-orleans.fr
AF: Laboratoire de Physique et Chimie de l'Environnement, Centre National de la Recherche Scientifique, 45071, Orleans, Cedex 2 France
AB: Recent studies have statistically shown that the magnetic reconnection site at substorm expansion onset is located in the magnetotail at X ~ -20 R_E on average. For a substorm event that occurred at ~0153 UT on 2 July 1996, however, Geotail observed a series of tailward, but slow, flows with southward magnetic fields fairly close to the Earth at (X, Y) ~ (-7, 9) R_E. The flows had enhancements of the total pressure and the total magnetic field as well as bidirectional field-aligned low-energy electrons in their central part. We interpret these as signatures for tailward-moving small plasmoids with scales of ~0.5-3 R_E. Considering that GOES-8 observed a dipolarization at (X, Y) ~ (-4, 5) R_E after the expansion onset, we estimate that the magnetic reconnection occurred between the Geotail and GOES-8 positions. UVI auroral images from Polar and ground magnetic field data show that this substorm, initiated at ~20 hours MLT and ~64° magnetic latitude, was not very intense, and the period examined was not during an intense storm. The southward interplanetary magnetic field (IMF) was not very large, while the large duskward IMF persisted for more than 12 hours before the onset as well as the somewhat large solar wind dynamic pressure. It seems likely that the global ionospheric convection was not very strong. Locally enhanced convection and auroral oval expansion due to the large IMF B_y and the solar wind dynamic pressure might lead to the initiation of the magnetic reconnection much closer to the Earth than usual.
DE: 2704 Auroral phenomena (2407)
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2744 Magnetotail
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005