Physics of auroral phenomena : proceedings of the 38th annual seminar, Apatity, 2-6 march, 2015 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Издательство Кольского научного центра РАН, 2015. - 189 с. : ил., табл.

Field-aligned current dynamics during two substorms 3. Summary 1. From the data on the 2000 April 6 two selected events, we calculated the maps for FAC density distribution in the polar ionosphere of the Northern Hemisphere. In each event, sufficient signatures of expansion phase were observed. In one of them, we describe the EP type termed "summer," and the one termed "winter" in the other event. 2. We propose a scenario for the global EP, where this substorm phase evolves simultaneously in the summer and winter hemispheres, but in different MLT sectors of the nightside Rl offered: the winter (summer) type EP is observed in the Rl postmidnight (premidnight) sector. These two sectors are within the ~ (18-06) MLT interval, and their centers are separated by ~ 6 MLT. 3. We substantiated the conclusion that the M-I feedback instability in the Rl premidnight sector of the summer hemisphere serves as an initiator and an organizer of the global EP. 4. In the winter hemisphere, a collapse (a decrease in the downward FAC intensity) of the Rl premidnight sector FAC system evolves simultaneously with the EP of the postmidnight sector. We describe the physics of this collapse within the model for the electric circuit of the common current system in the global EP M-I system. 5. We described the phenomena of spontaneous reconfiguration of the FAC density and intensity distribution in Rl and other Iijima and Potemra Regions. The reconfiguration is observed as a variation in the FAC density and intensity distributions in I-P Regions. These variations produce an expansion/compression of the downward FAC sector due to a compression/expansion of the upward FAC in the adjacent sector of the same Region. These phenomena are described in terms of azimuthal "twisting" of the FAC density spatial distribution in each I-P Region (clockwise or counter-clockwise). 6. We propose a conceptual model for twisting phenomena based on the supplemented model from Lui and Kamide [2003]. In general, we suggest an empirical scenario for the global EP involving principally new elements, as compared with the known substorm scenarios. We introduced the new elements based on combining the data on two hemispheres, winter and summer, within a uniform model for the electric circuit of the M-I current system. Unlike such an approach, the known empirical substorm scenarios are primarily made on the database for the Northern Hemisphere. In this case, the strong asymmetry of two hemispheres - the key element of the proposed EP scenario - is not taken into account. Acknowledgements. We thank the ISTP SB RAS MIT group members for stimulating discussions. The AE index was obtained from the World Data Center for Geomagnetism, Kyoto. 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