Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

Daysidepolar substorm behavior: Case study seen the significant change in the high-latitude ionosphere convection structure. Before and after the discussed dayside substorm, there was the two-vortex convection distribution. When the IMF Bz became large positive, and the IMF By becamc large negative, the convection vortices weakened. However, some small additional vortices appeared near noon and demonstrated a complicated spatial structure of the correspondent field aligned currents (FACs) enhancements. W.4C-0M2 UT f? S': $ : l b № I . •tbK'Mo »3Atoft/2017 ЯКЮ-9MS »Л Figure 4. SUPERDARN radar data (before, during and after the “dayside polar substorm”). The auroral oval location according to the OVATION model [http://www.jhuapl.edu/Aurora/ovation] is presented in Fig. 5. This map shows that the high-latitude IMAGE station at Svalbard (NAL and LYR) which recorded the strongest amplitude of the “dayside polar substorm” (Fig. 2) were located in vicinity of the poleward boundary of the auroral oval. NORTH CAP End Time 22 Jan 2012 - 11:00 DMSP Satellite : F16 No UVI Data for this period. 180 Normalized B2i - 62 Flu* - 5S3 MWb Equivalent Kp «. 3.0 Global в - E— Flux - 23.0 MW Figure 5. The auroral oval location according to Figure 6. Schema of the electrojets space-time the OVATION model. distribution during a substorm with A L - -800 nT (after Feldstein et al., 2006). Discussion We suppose that the source of the considered “dayside polar substorm” recorded during the initial phase of the magnetic storm on January 2012 could be the intensification of high-latitude field aligned currents (FACs) which were seen in the AMPERE and SUPERDARN data. These FACs could be interpreted as the polar-latitude NBZ current system developing [Iijima et al., 1984]. However, we have to note the NBZ system has been mapped into the polar cap, but the considered daytime magnetic bay was observed near the poleward boundary of aurora oval, probably, inside the closed magnetosphere. 25