Articles | Volume 29, issue 9
Ann. Geophys., 29, 1549–1569, 2011

Special issue: Cluster 10th anniversary workshop

Ann. Geophys., 29, 1549–1569, 2011

  08 Sep 2011

08 Sep 2011

Interplanetary magnetic field rotations followed from L1 to the ground: the response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

M. Volwerk1, J. Berchem2, Y. V. Bogdanova3, O. D. Constantinescu4, M. W. Dunlop5, J. P. Eastwood6, P. Escoubet7, A. N. Fazakerley3, H. Frey8, H. Hasegawa9, B. Lavraud10,11, E. V. Panov1, C. Shen12, J. K. Shi12, M. G. G. T. Taylor7, J. Wang13, J. A. Wild14, Q. H. Zhang15, O. Amm16, and J. M. Weygand2 M. Volwerk et al.
  • 1Space Research Insitute, Austrian Academy of Sciences, 8042 Graz, Austria
  • 2IGPP UCLA, Los Angeles, CA, USA
  • 3Mullard Space Science Laboratory, University College London, Dorking, UK
  • 4Institut für Geophysik und extraterrestrische Physik, Technische Universität, 38106 Braunschweig, Germany
  • 5Department of Space Sciences, Rutherford Appleton Laboratory, Didcot, UK
  • 6Blackett Laboratory, Imperial College London, London, UK
  • 7ESTEC, Noordwijk, The Netherlands
  • 8SSL, University of California, Berkeley, CA, USA
  • 9Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan
  • 10Centre d'\'Etude Spatiale des Rayonnements, Université de Toulouse, Toulouse, France
  • 11Centre National de la Recherche Scientifique, UMR 5187, Toulouse, France
  • 12CSSAR, Chinese Academy of Sciences, Beijing, China
  • 13Peking Universtity, Beijing, China
  • 14Department of Physics, Lancaster University, Lancaster, UK
  • 15SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai, China
  • 16Arctic Research Unit, Finnish Meteorological Institute, Helsinki, Finland

Abstract. A study of the interaction of solar wind magnetic field rotations with the Earth's magnetosphere is performed. For this event there is, for the first time, a full coverage over the dayside magnetosphere with multiple (multi)spacecraft missions from dawn to dusk, combined with ground magnetometers, radar and an auroral camera, this gives a unique coverage of the response of the Earth's magnetosphere. After a long period of southward IMF Bz and high dynamic pressure of the solar wind, the Earth's magnetosphere is eroded and compressed and reacts quickly to the turning of the magnetic field. We use data from the solar wind monitors ACE and Wind and from magnetospheric missions Cluster, THEMIS, DoubleStar and Geotail to investigate the behaviour of the magnetic rotations as they move through the bow shock and magnetosheath. The response of the magnetosphere is investigated through ground magnetometers and auroral keograms. It is found that the solar wind magnetic field drapes over the magnetopause, while still co-moving with the plasma flow at the flanks. The magnetopause reacts quickly to IMF Bz changes, setting up field aligned currents, poleward moving aurorae and strong ionospheric convection. Timing of the structures between the solar wind, magnetosheath and the ground shows that the advection time of the structures, using the solar wind velocity, correlates well with the timing differences between the spacecraft. The reaction time of the magnetopause and the ionospheric current systems to changes in the magnetosheath Bz seem to be almost immediate, allowing for the advection of the structure measured by the spacecraft closest to the magnetopause.