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.

L.I. Gromova and S. V. Gromov Discussion Fig. 3 demonstrates IMF Bz and By components, the horizontal vectors of the geomagnetic field and the AMPERE data for the event of June 23, 2015. The horizontal vectors of the geomagnetic field presented in Fig. 3 (and below in Fig. 4) were constructed on the base of difference magnetograms (see Fig. 2). The AMPERE data shows reduced magnetic field residual data showing the horizontal plane vector data of magnetic perturbation and the radial current density. The ground magnetic vectors demonstrate the counter-clockwise magnetic vortex above high-latitude IMAGE stations (Fig. 3a). This vortex could be regarded as a proxy of an intensification o f upward field-aligned currents. The AMPERE model demonstrates very intensive upward FACs (Fig. 3b) expanded poleward. We suppose due to the southern IMF Bz was more intensive than IMF By, the intensification of the FACs o f region 1 in the polar latitudes produced by the ionospheric current system controlled by Bz see Fig. 2a). These currents (named DP2 current system) increase under IMF By > 0 in the postnoon sector of the Northern hemisphere [Troshichev et al., 1982]. Thus the intensification of FACs of the Region 1 [Iijima and Potemra, 1976] could be a source o f a high-latitude bay-like magnetic disturbances, such as the examined dayside negative magnetic bay shown in Fig. la. June 23, 2015 Figure 3. a) IMF Bz and By components and the horizontal vectors of the geomagnetic field; b) The AMPERE data: reduced magnetic field residual data showing the horizontal plane vector data of magnetic perturbation (upper)', the radial current density (bottom). Upward currents are shown in red and downward currents in blue, yellow circle shows the position of the high latitude IMAGE stations. Fig. 4 presents the ground magnetic vectors and DMSP F13 precipitating particle data for the events of May 24, 2000. The ground magnetic vectors don’t demonstrate any pronounced magnetic vortex above high-latitude IMAGE stations (Fig. 4a). It is apparent from the DMSP F13 spectrograms of the precipitating particles that there was no particle (ions and electrons) enhancement in the same area as the examined dayside polar magnetic bays were observed (Fig. 4b). We suppose that FACs are weak and do not provide increasing of the geomagnetic activity in the high- latitudes. When the IMF By predominates over the IMF Bz, the high-latitude DPY current system controlled by the IMF By sign intensified, penetrating deep into the polar cap [ Vennerstrom et al., 2002] and produced sequence of dayside polar magnetic bays. On May 24, 2000 (Fig. 2b) the sequence of positive and negative bays occurred under the positive or negative IMF By be probably caused by the eastward or westward polar electrojets respectively [Feldstein et al., 2006]. We suppose that due to the IMF By was more intensive than IMF Bz, DPY current system controlled by the IMF By sign (eastward and westward electrojets) produced such sequence of dayside polar magnetic bays. 21