Articles | Volume 25, issue 7
Ann. Geophys., 25, 1669–1690, 2007
Ann. Geophys., 25, 1669–1690, 2007

  30 Jul 2007

30 Jul 2007

Motion of flux transfer events: a test of the Cooling model

R. C. Fear1, S. E. Milan1, A. N. Fazakerley2, C. J. Owen2, T. Asikainen3, M. G. G. T. Taylor4, E. A. Lucek5, H. Rème6, I. Dandouras6, and P. W. Daly7 R. C. Fear et al.
  • 1Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK
  • 2Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
  • 3Department of Physical Sciences, University of Oulu, P.O. Box 3000, 90014, Finland
  • 4Research and Scientific Support Department, European Space Agency, 2201AZ Noordwijk, The Netherlands
  • 5Blackett Laboratory, Imperial College, Prince Consort Road, London, SW7 2BZ, UK
  • 6CESR/CNRS, 9 Avenue du Colonel Roche, B.P. 4346, 31028 Toulouse Cedex 4, France
  • 7Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany

Abstract. The simple model of reconnected field line motion developed by Cooling et al. (2001) has been used in several recent case studies to explain the motion of flux transfer events across the magnetopause. We examine 213 FTEs observed by all four Cluster spacecraft under a variety of IMF conditions between November 2002 and June 2003, when the spacecraft tetrahedron separation was ~5000 km. Observed velocities were calculated from multi-spacecraft timing analysis, and compared with the velocities predicted by the Cooling model in order to check the validity of the model. After excluding three categories of FTEs (events with poorly defined velocities, a significant velocity component out of the magnetopause surface, or a scale size of less than 5000 km), we were left with a sample of 118 events. 78% of these events were consistent in both direction of motion and speed with one of the two model de Hoffmann-Teller (dHT) velocities calculated from the Cooling model (to within 30° and a factor of two in the speed). We also examined the plasma signatures of several magnetosheath FTEs; the electron signatures confirm the hemisphere of connection indicated by the model in most cases. This indicates that although the model is a simple one, it is a useful tool for identifying the source regions of FTEs.