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Volume 20, issue 3
Ann. Geophys., 20, 341–347, 2002
https://doi.org/10.5194/angeo-20-341-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue: INTERBALL

Ann. Geophys., 20, 341–347, 2002
https://doi.org/10.5194/angeo-20-341-2002
© Author(s) 2002. This work is distributed under
the Creative Commons Attribution 3.0 License.

  31 Mar 2002

31 Mar 2002

Plasma sheet fast flows and auroral dynamics during substorm: a case study

N. L. Borodkova1, A. G. Yahnin2, K. Liou3, J.-A. Sauvaud4, A. O. Fedorov*,4, V. N. Lutsenko1, M. N. Nozdrachev1, and A. A. Lyubchich2 N. L. Borodkova et al.
  • 1Space Research Institute, Russian Academy of Sciences, Moscow, Russia
  • 2Polar Geophysical Institute, Apatity, Russia
  • 3Applied Physics Laboratory, Johns Hopkins University, Laurel, USA
  • 4Centre d’Etude Spatiale des Rayonnements, Toulouse, France
  • *On leave from the Space Research Institute, Moscow
  • Correspondence to: J.-A. Sauvaud (sauvaud@cesr.cnes.fr)

Abstract. Interball-1 observations of a substorm development in the mid-tail on 16 December 1998 are compared with the auroral dynamics obtained from the Polar UV imager. Using these data, the relationship between plasma flow directions in the tail and the location of the auroral activation is examined. Main attention is given to tailward and earth-ward plasma flows, interpreted as signatures of a Near Earth Neutral Line (NENL). It is unambiguously shown that in the mid-plasma sheet the flows were directed tailward when the auroral bulge developed equatorward of the spacecraft ionospheric footprint. On the contrary, when active auroras moved poleward of the Interball-1 projection, earthward fast flow bursts were observed. This confirms the concept that the NENL (or flow reversal region) is the source of auroras forming the poleward edge of the auroral bulge. The observed earthward flow bursts have all typical signatures of Bursty Bulk Flows (BBFs), described by Angelopolous et al. (1992). These BBFs are related to substorm activations starting at the poleward edge of the expanded auroral bulge. We interpret the BBFs as a result of reconnection pulses occurring tail-ward of Interball-1. In addition, some non-typically observed phenomena were detected in the plasma sheet during this substorm: (i) tailward/earthward flows were superimposed on a very strong duskward flow, and (ii) wavy structures of both magnetic field and plasma density were registered. The latter observation is probably linked to the filamentary structure of the current sheet.

Key words. Magnetospheric physics (auroral phenomena; plasma sheet; storms and substorms)

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