Articles | Volume 29, issue 9
Ann. Geophys., 29, 1683–1697, 2011

Special issue: Cluster 10th anniversary workshop

Ann. Geophys., 29, 1683–1697, 2011

  29 Sep 2011

29 Sep 2011

Magnetopause reconnection across wide local time

M. W. Dunlop1,10,12, Q.-H. Zhang2, Y. V. Bogdanova3, K. J. Trattner4, Z. Pu5, H. Hasegawa6, J. Berchem7, M. G. G. T. Taylor8, M. Volwerk9, J. P. Eastwood10, B. Lavraud11, C. Shen12, J.-K. Shi12, J. Wang5, D. Constantinescu13, A. N. Fazakerley3, H. Frey14, D. Sibeck15, P. Escoubet8, J. A. Wild16, Z. X. Liu12, and C. Carr10 M. W. Dunlop et al.
  • 1SSTD, RAL, Chilton, DIDCOT, Oxfordshire, OX11 0QX, UK
  • 2SOA Key Laboratory for Polar Science, Polar Research Institute of China, Shanghai 200136, China
  • 3MSSL, University College London, Dorking, Surrey, RH5 6NT, UK
  • 4Lockheed Martin, Palo Alto, CA, USA
  • 5School of Earth and Space Sciences, Peking University, Beijing 100871, China
  • 6Institute of Space and Astronautical Science, JAXA, Japan
  • 7IGPP – UCLA, 3877 Slichter Hall, Los Angeles, CA 90095-1567, USA
  • 8ESA/ESTEC, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands
  • 9Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
  • 10The Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
  • 11IRAP – CNRS, 9 Ave. du Colonel Roche, 31028 Toulouse Cedex 4, France
  • 12CSSAR, Chinese Academy of Sciences, Beijing 100190, China
  • 13Institut für Geophysik und Meteorologie, TU-BS, 38106 Braunschweig, Germany
  • 14Space Sciences Lab., University of California, 7 Gauss Way, Berkeley, CA 94720-7450, USA
  • 15Code 674, NASA/GSFC, Greenbelt, MD 20771, USA
  • 16Space Plasma Environment and Radio Science group, Lancaster University, LA1 4WA, UK

Abstract. During April to July 2007 a combination of 10 spacecraft provided simultaneous monitoring of the dayside magnetopause across a wide range of local times. The array of four Cluster spacecraft, separated at large distances (10 000 km), were traversing the dawn-side magnetopause at high and low latitudes; the five THEMIS spacecraft were often in a 4 + 1 grouped configuration, traversing the low latitude, dusk-side magnetosphere, and the Double star, TC-1 spacecraft was in an equatorial orbit between the local times of the THEMIS and Cluster orbits. We show here a number of near simultaneous conjunctions of all 10 spacecraft at the magnetopause. One conjunction identifies an extended magnetic reconnection X-line, tilted in the low latitude, sub-solar region, which exists together with active anti-parallel reconnection sites extending to locations on the dawn-side flank. Oppositely moving FTE's are observed on all spacecraft, consistent with the initially strong IMF By conditions and the comparative locations of the spacecraft both dusk-ward and dawn-ward of noon. Comparison with other conjunctions of magnetopause crossings, which are also distributed over wide local times, supports the result that reconnection activity may occur at many sites simultaneously across the sub-solar and flank magnetopause, but linked to the large scale (extended) configuration of the merging line; broadly depending on IMF orientation. The occurrence of MR therefore inherently follows a "component" driven scenario irrespective of the guide field conditions. Some conjunctions allow the global magnetopause response to IMF changes to be observed and the distribution of spacecraft can directly confirm its shape, motion and deformation at local noon, dawn and dusk-side, simultaneously.