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1 IKI - Space Research Institute of the Russian Academy of Sciences 2 Polar Geophysical Institute 3 Applied Physics Laboratory 4 CESR - Centre d-étude spatiale des rayonnements

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.





Autor: N. L. Borodkova - A. G. Yahnin - K. Liou - J.-A. Sauvaud - A. O. Fedorov - V. N. Lutsenko - M. N. Nozdrachev - A. A. Lyubchich -

Fuente: https://hal.archives-ouvertes.fr/



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