Indirect mapping of the source of the oppositely directed fast plasma flows in the plasma sheet onto the auroral display

摘要

Data from Polar and Geotail spacecraft are combined to investigate therelationship between locations of active auroras and the magnetotail plasmasheet region where reversed fast plasma flows are generatedduring substorms. Using the magnetospheric magnetic field model, it is shownthat at the beginning of the tailward fast flow the ionospheric footprint ofthe spacecraft measuring the flow tends to be located poleward of theauroral bulge. The spacecraft within the earthward flow is mappedequatorward of the poleward edge of the auroral bulge. We conclude that asource of the fast plasma flows is conjugated with the poleward edge of theauroral bulge. Analysis of the behavior of the plasma and the magnetic fieldin the vicinity of the source of the diverging flows allows us to concludethat the source region, interpreted as the magnetic reconnection site,coincides with the region of the cross-tail current reduction, and thetailward propagation of the region is associated with the tailwardpropagation of the current disruption front.