Japan Geoscience Union Meeting 2016

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International Session (Oral)

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

[P-EM06] Magnetospheric Multi-Scale (MMS) mission -- A new age of magnetospheric physics

Tue. May 24, 2016 10:45 AM - 12:15 PM 103 (1F)

Convener:*Seiji Zenitani(National Astronomical Observatory of Japan), Naritoshi Kitamura(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Yoshifumi Saito(Solar System Science Division, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), Paul Cassak(West Virginia University), Li-Jen Chen(NASA Goddard Space Flight Center), Craig Pollock(NASA Goddard Space Flight Center), Chair:Craig James Pollock, Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University)

11:00 AM - 11:15 AM

[PEM06-08] Structure of the magnetopause during quasi-continuous spatially-extended magnetic reconnection: Geotail and MMS conjunction on 2015-10-02

★Invited papers

*Hiroshi Hasegawa1, Naritoshi Kitamura1, Yoshifumi Saito1, Iku Shinohara1, Shoichiro Yokota1, Tsugunobu Nagai2, Seiji Zenitani3, The MMS team (1.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 2.Tokyo Institute of Technology, 3.National Astronomical Observatory of Japan)

Keywords:magnetic reconnection, magnetopause, ion diffusion region

We present observations on 2 October 2015 when Geotail, near the Earth’s equatorial plane, and Magnetospheric Multiscale (MMS), at mid-southern latitudes, simultaneously traversed the Earth’s postnoon magnetopause and detected southward magnetic reconnection jets under southward interplanetary magnetic field (IMF) conditions. Such fortuitous observations allow us to estimate the length of the reconnection site, and to reveal spatial evolution of the jets along the magnetopause. Our observations show that the primary reconnection X-line under modest solar wind Alfven Mach number condition can be extended over a wide range of local time and remain active for hours. During a due southward IMF interval when anti-parallel reconnection was occurring, MMS encountered a localized ion-scale current sheet within the jet far downstream (>300 ion inertial lengths) of the primary reconnection site. The current sheet contained super-Alfvenic perpendicular electron flow, perpendicular electric current of order 500 nA/m2, electron flow reversal, and both Hall current and Hall magnetic field signatures. The observations are consistent with the occurrence of secondary reconnection within the jets of quasi-continuous spatially-extended reconnection. It appears that the primary site of magnetopause reconnection under favorable conditions is two-dimensional, but the resulting reconnection jets and secondary reconnection are three-dimensional.