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Ann. Geophys., 24, 679-687, 2006
www.ann-geophys.net/24/679/2006/
© European Geosciences Union 2006
Indirect mapping of the source of the oppositely directed fast plasma flows in the plasma sheet onto the auroral display
A. G. Yahnin1, I. V. Despirak1, A. A. Lubchich1, B. V. Kozelov1, N. P. Dmitrieva2, M. A. Shukhtina2, and H. K. Biernat3
1Polar Geophysical Institute, Kola Science Center of the Russian Academy of Sciences, Apatity, Russia
2Institute of Physics, Sankt-Petersburg State University, Sankt-Petersburg, Russia
3Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Abstract. Data from Polar and Geotail spacecraft are combined to investigate the
relationship between locations of active auroras and the magnetotail plasma
sheet region where reversed fast plasma flows are generated
during substorms. Using the magnetospheric magnetic field model, it is shown
that at the beginning of the tailward fast flow the ionospheric footprint of
the spacecraft measuring the flow tends to be located poleward of the
auroral bulge. The spacecraft within the earthward flow is mapped
equatorward of the poleward edge of the auroral bulge. We conclude that a
source of the fast plasma flows is conjugated with the poleward edge of the
auroral bulge. Analysis of the behavior of the plasma and the magnetic field
in the vicinity of the source of the diverging flows allows us to conclude
that the source region, interpreted as the magnetic reconnection site,
coincides with the region of the cross-tail current reduction, and the
tailward propagation of the region is associated with the tailward
propagation of the current disruption front.
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