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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 7
Ann. Geophys., 16, 775–786, 1998
https://doi.org/10.1007/s00585-998-0775-5
© European Geosciences Union 1998
Ann. Geophys., 16, 775–786, 1998
https://doi.org/10.1007/s00585-998-0775-5
© European Geosciences Union 1998

  31 Jul 1998

31 Jul 1998

Observations of substorm fine structure

L. L. Lazutin1, R. Rasinkangas2, T. V. Kozelova1, A. Korth3, H. Singer4, G. Reeves5, W. Riedler6, K. Torkar6, and B. B. Gvozdevsky1 L. L. Lazutin et al.
  • 1Polar Geophysical Institute, Russian Academy of Sciences, Apatity, Murmansk Region, 184200, Russia
  • 2University of Oulu, Department of Physical Sciences, FIN-90570 Oulu, Finland
  • 3Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany
  • 4Space Environment Center, NOAA, 325 Broadway, Boulder, CO 80303-3328, USA
  • 5Los Alamos National Laboratory, Los Alamos, NM 87545, USA
  • 6Institute of Space Research of the Austrian Academy of Sciences, A-8010 Graz, Austria

Abstract. Particle and magnetic field measurements on the CRRES satellite were used, together with geosynchronous satellites and ground-based observations, to investigate the fine structure of a magnetospheric substorm on February 9, 1991. Using the variations in the electron fluxes, the substorm activity was divided into several intensifications lasting about 3–15 minutes each. The two main features of the data were: (1) the intensifications showed internal fine structure in the time scale of about 2 minutes or less. We call these shorter periods activations. Energetic electrons and protons at the closest geosynchronous spacecraft (1990 095) were found to have comparable activation structure. (2) The energetic (>69 keV) proton injections were delayed with respect to electron injections, and actually coincided in time with the end of the intensifications and partial returns to locally more stretched field line configuration. We propose that the energetic protons could be able to control the dynamics of the system locally be quenching the ongoing intensification and possibly preparing the final large-scale poleward movement of the activity. It was also shown that these protons originated from the same intensification as the preceeding electrons. Therefore, the substorm instability responsible for the intensifications could introduce a negative feedback loop into the system, creating the observed fine structure with the intensification time scales.

Key words. Magnetospheric Physics (Storms and substorms).

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