Articles | Volume 22, issue 6
Ann. Geophys., 22, 2097–2105, 2004
Ann. Geophys., 22, 2097–2105, 2004

  14 Jun 2004

14 Jun 2004

Pi2-pulsations observed in energetic electron precipitation and magnetic field in association with a substorm surge

A. Åsnes1, J. Stadsnes1, J. Bjordal1, N. Østgaard3,2, D. L. Detrick4, T. J. Rosenberg4, and S. E. Haaland5,6 A. Åsnes et al.
  • 1Department of Physics, University of Bergen, Allegt. 55, 5007 Bergen, Norway
  • 2NASA/Goddard Space Flight Center, Greenbelt, MD 20771,USA
  • 3University of California, Berkeley, CA94720-7450, USA
  • 4University of Maryland, College Park, MD 20 742–24 331, USA
  • 5International Space Science Institute, Switzerland
  • 6Max-Planck Institut für extraterrestrische Physik (MPE), Garching , Germany

Abstract. For a substorm 24 July 1998 PIXIE observes the onset and expansion during a perigee pass of the Polar satellite. This gives an opportunity to follow the evolution of the onset and expansion phase, almost on a global scale with relatively high temporal resolution. The substorm is presented with multiple observations throughout the magnetosphere. Following the onset of the substorm we observe a localised region of modulated energetic electron fluxes following the passage of the westward travelling surge in the pre-midnight region. We count at least six clear pulses with a period of approximately one minute. Concurrent magnetic ground measurements show similar characteristics, almost simultaneously with the pulses in precipitation. We propose several possible mechanism for the pulsations, amongst them the theory of modulated wave particle interaction first proposed by coroniti70.