Published in

European Geosciences Union, Annales Geophysicae, 2(33), p. 169-184, 2015

DOI: 10.5194/angeo-33-169-2015

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Dual-spacecraft reconstruction of a three-dimensional magnetic flux rope at the Earth's magnetopause

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Data provided by SHERPA/RoMEO

Abstract

We present the first results of a data analysis method, developed by Sonnerup and Hasegawa (2011), for reconstructing three-dimensional (3-D), magnetohydrostatic structures from data taken as two closely spaced satellites traverse the structures. The method is applied to a mag-netic flux transfer event (FTE), which was encountered on 27 June 2007 by at least three (TH-C, TH-D, and TH-E) of the five THEMIS probes near the subsolar magnetopause. The FTE was sandwiched between two oppositely directed reconnection jets under a southward interplanetary magnetic field condition, consistent with its generation by multiple X-line reconnection. The recovered 3-D field indicates that a magnetic flux rope with a diameter of ∼ 3000 km was em-bedded in the magnetopause. The FTE flux rope had a signif-icant 3-D structure, because the 3-D field reconstructed from the data from TH-C and TH-D (separated by ∼ 390 km) bet-ter predicts magnetic field variations actually measured along the TH-E path than does the 2-D Grad–Shafranov reconstruc-tion using the data from TH-C (which was closer to TH-E than TH-D and was at ∼ 1250 km from TH-E). Such a 3-D nature suggests that the field lines reconnected at the two X-lines on both sides of the flux rope are entangled in a com-plicated way through their interaction with each other. The generation process of the observed 3-D flux rope is discussed on the basis of the reconstruction results and the pitch-angle distribution of electrons observed in and around the FTE. Keywords. Magnetospheric physics (magnetopause cusp and boundary layers) – space plasma physics (magnetic re-connection; instruments and techniques)