Articles | Volume 30, issue 2
Ann. Geophys., 30, 379–387, 2012

Special issue: Cluster 10th anniversary workshop

Ann. Geophys., 30, 379–387, 2012

Regular paper 22 Feb 2012

Regular paper | 22 Feb 2012

Global magnetospheric response to an interplanetary shock: THEMIS observations

H. Zhang1, D. G. Sibeck2, Q.-G. Zong3,4, J. P. McFadden5, D. Larson5, K.-H. Glassmeier6, and V. Angelopoulos7 H. Zhang et al.
  • 1Geophysical Institute, University of Alaska Fairbanks, AK, USA
  • 2NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 3Center for Atmospheric Research, University of Massachusetts, Lowell, USA
  • 4Institute of Space Physics and Applied Technology, Peking University, Beijing, China
  • 5Space Sciences Laboratory, University of California, Berkeley, CA, USA
  • 6Institute for Geopysics and Extraterrestrial Physics, TU Braunschweig, Germany
  • 7IGPP/ESS UCLA, Los Angeles, CA 90095-1567, USA

Abstract. We investigate the global response of the geospace plasma environment to an interplanetary (IP) shock at ~02:24 UT on 28 May 2008 from multiple THEMIS spacecraft observations in the magnetosheath (THEMIS B and C), the mid-afternoon magnetosphere (THEMIS A), and the dusk magnetosphere (THEMIS D and E). The interaction of the transmitted IP shock with the magnetosphere has global effects. Consequently, it can affect geospace plasma significantly. After interacting with the bow shock, the IP shock transmitted a fast shock and a discontinuity which propagated through the magnetosheath toward the Earth at speeds of 301 km s−1 and 137 km s−1, respectively. THEMIS A observations indicate that the IP shock changed the properties of a plasmaspheric plume significantly. The plasmaspheric plume density increased rapidly from 10 to 100 cm−3 in 4 min and the ion distribution changed from an isotropic to a strongly anisotropic distribution. Electromagnetic ion cyclotron (EMIC) waves observed by THEMIS A are most likely excited by the anisotropic ion distributions caused by the IP shock impact. THEMIS A, but not D or E, observed a plasmaspheric plume in the dayside magnetosphere. Multiple spacecraft observations indicate that the dawn-side edge of the plasmaspheric plume was located between THEMIS A and D (or E).