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Ann. Geophys., 26, 709-724, 2008
www.ann-geophys.net/26/709/2008/
© European Geosciences Union 2008

Structure of the near-Earth plasma sheet during tailward flows

A. Runov^1,*, I. Voronkov², Y. Asano³, W. Baumjohann¹, M. Fujimoto⁴, R. Nakamura¹, T. Takada¹, M. Volwerk^1,5, Z. Vörös^1,6, M. Meurant², A. Fazakerley⁷, H. Rème⁸, and A. Balogh^9
1Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
²University of Calgary, Calgary, Canada
³Tokyo Institute of Technology, Tokyo, Japan
⁴Institute of Space and Astronautical Sciences, JAXA, Kanagawa, Japan
⁵Max Plank Institute for Extraterrestrial Physics, Garching, Germany
⁶Institute of Atmospheric Physics, Prague, Czech Republic
⁷Mullard Space Science Laboratory, UCL, London, UK
⁸Centre d'Etude Spatiale des Rayonnements, Toulouse, France
⁹Imperial College, London, UK
^*now at: Institute of Geophysics and Planetary Physics, UCLA, Los Angeles, CA, USA

Abstract. A detailed analysis of successive tailward flow bursts in the near-Earth magnetotail (X~−19 R_E) plasma sheet is performed on the basis of in-situ multi-point observations by the Cluster spacecraft on 15 September 2001. The tailward flows were detected during a northward IMF interval, 2.5 h after a substorm expansion. Each flow burst (V_x<300 km/s) was associated with local auroral activation. Enhancements of the parallel and anti-parallel ~1 keV electron flux were detected during the flows. The spacecraft configuration enables to monitor the neutral sheet (B_x≈0) and the level of B_x≈10–15 nT simultaneously, giving a possibility to distinguish between closed plasmoid-like structures and open NFTE-like surges. The data analysis shows NFTE-like structures and localized current filaments embedded into the tailward plasma flow. 3-D shapes of the structures were reconstructed using the four-point magnetic filed measurements and the particle data.

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