Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM09] Dynamics in magnetosphere and ionosphere

Thu. May 28, 2015 11:00 AM - 11:45 AM 302 (3F)

Convener:*Shin'ya Nakano(The Institute of Statistical Mathematics), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Hiroshi Hasegawa(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Nagoya University Solar Terrestrial Environment Laboratory Geospace Research Center), Chair:Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University)

11:30 AM - 11:45 AM

[PEM09-24] Kink-type oscillations of the magnetotail current sheet with a quasi-continuous magnetic reconnection jet

*Hiroshi HASEGAWA1, Iku SHINOHARA1, Tsugunobu NAGAI2, Yoshifumi SAITO1 (1.Institute of Space and Astronautical Science, JAXA, 2.Tokyo Institute of Technology)

Keywords:magnetic reconnection, magnetotail, current sheet, kink-mode, Grad-Shafranov equation, steady magnetospheric convection

We present and analyze quasi-periodic crossings of the magnetotail current sheet observed by the Geotail spacecraft at (-26, 9, 0) Re in GSM on 11 October 2014. The event occurred when the magnetosphere was moderately driven by the solar wind and southward interplanetary magnetic field, i.e., during a period of so-called steady magnetospheric convection. Reconnection jets with an earthward velocity 〜700 km/s, comparable to the lobe Alfven speed, were observed almost continuously in the plasma sheet for an interval 0900-1100 UT. In order to reveal the orientation and structure of the observed current sheet, whose crossings occurred with a period of 2-3 minutes, we applied the Grad-Shafranov reconstruction technique [Hau and Sonnerup, 1999; Hu and Sonnerup, 2002] assuming 2-D structures. The results indicate that kink-type waves were propagating approximately earthward in the plasma sheet, with a wavelength of 〜15 Re and amplitude of order 1 Re. To the best of our knowledge, this is the first identification of sunward-propagating MHD-scale kink-mode waves in the magnetotail. The generation mechanism of the observed oscillations is discussed based on the nature of the reconstructed current sheet structures, ion velocity distributions observed in the current sheet, and results from other single-spacecraft methods such as minimum variance analysis and minimum Faraday residue method [Terasawa et al., 1996; Khrabrov and Sonnerup, 1998].

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