ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-31-555-2013 Analysis of the substructure within a complex magnetic cloud on 3–4 September 2008 Andreeova K. 1 Kilpua E. K. J. 1 Hietala H. https://orcid.org/0000-0002-3039-1255 1 3 Koskinen H. E. J. 1 2 Isavnin A. https://orcid.org/0000-0002-7178-627X 1 Vainio R. 1 Department of Physics, P.O. Box 64, University of Helsinki, Finland Finnish Meteorological Institute, Helsinki, Finland currently at: Imperial College, London, UK 21 03 2013 31 3 555 562 Copyright: © 2013 K. Andreeova et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/31/555/2013/angeo-31-555-2013.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/31/555/2013/angeo-31-555-2013.pdf

In this paper we have analyzed a substructure found within a leading part of a north–south-oriented magnetic cloud (MC) observed on 3–4 September 2008 in the near-Earth solar wind by multiple spacecraft (ACE, Wind, THEMIS B and C). The MC was preceded by a stream interface (SI) and followed by a high-speed stream (HSS). The identified substructure featured a strong depletion of suprathermal halo electrons and showed distinct magnetic field and plasma signatures. It occurred where suprathermal electron flow within a cloud changed from bidirectional to unidirectional, indicating change in the field line connectivity to the Sun. We found that the substructure maintained roughly its integrity from the first Lagrangian point to the vicinity of the Earth's bow shock in the front edge of the MC, but revealed small changes in the structure which could be explained either by temporal evolution or spatial configuration of the spacecraft.

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