HR: 0800h
AN: SM31A-1210    [Abstracts]
TI: Signature of tail current disruption in the near-Earth plasma sheet
AU: * Shiokawa, K
EM: shiokawa@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, NagoyanUniversity, 3-13, Honohara, Toyokawa, 442-8507 Japan
AU: Miyashita, Y
EM: miyasita@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, NagoyanUniversity, 3-13, Honohara, Toyokawa, 442-8507 Japan
AU: Shinohara, I
EM: iku@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Sciences, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, 229-8510 Japan
AU: Matsuoka, A
EM: matsuoka@stp.isas.jaxa.jp
AF: Institute of Space and Astronautical Sciences, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, 229-8510 Japan
AB: We investigate a sequential dipolarization event in the near-Earth plasma sheet observed by the GEOTAIL satellite on August 31, 1999, at (Xgsm, Ygsm)=(-8.3 Re, -5.1 Re), using high-time-resolution data of a fluxgate magnetometer (16-Hz sample), a search-coil magnetometer (128 Hz), and electric field (64 Hz). Two dipolarizations were observed during a short time interval of 3 min. The elevation angles of magnetic field suddenly decreased 2-4 s prior to the dipolarization. Using high-time resolution magnetic and electric field data, we found characteristic field oscillations with frequencies of 5-20 Hz and amplitudes of 1-3 mV/m at the time of the sudden decrease of elevation angle. We suggest that the sudden decrease of elevation angles prior to the dipolarization is a signature of tail current disruption, which is caused by the observed characteristic field oscillations.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2752 MHD waves and instabilities
DE: 2772 Plasma waves and instabilities
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting