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.A. Dremukhina et al. observed in the near-noon sector of polar latitudes, change sign to the opposite. This indicates a reorganization of FAC systems, associated with them. On the bottom panel of Fig. 3 auroral oval locations at UT=16:00 and UT=16:50 (that is, before and after the first pressure front) from the OVATION model are shown too. Black circles show the positions of observatories of the IMAGE and the North-American chain. The time UT=16:50 corresponds to the time between the first and second spans of the SWARM A on the top panel of Fig. 3. The auroral oval shows a noticeable expansion both towards the high and low latitudes at all MLT sectors. 21.06.2015 15:31 - 15:53 UT 21.06.2015 17:05 - 17:27 UT 21.06.2015 18:38 - 19:00 UT < - 100 nT 16:50 UT Figure 3. Magnetic field vectors from the SWARM A data (top panel) and positions of the auroral oval from the OVATION model [ http://sd-www.jhuapl.edu/Aurora/ovation] on June 21, 2015. The size of publication does not allow placing the all available data from satellites spans. Therefore, here we give magnetograms of SWARM A, demonstrating the response to the arrival of the most powerful, the first and third, shock fronts to the Earth. Fig. 4 shows trajectories o f SWARM A, С satellites (blue and red lines) on June 21-22, 2015 (top panel); variations of the east-west component d By of the geomagnetic field before and after arrivals o f shock fronts at 16:45 UT on June 21 and at 18:38 UT on June 22 (middle panel); spectrograms of the DMSP satellites in close time spans (bottom panel). Green line shows trajectories of the DMSP satellites. Since the trajectories of the satellites are presented in geographic coordinates, MLT of an entry and departure of the SWARM is shown on the top panel of Fig. 3. From the measured variations of the magnetic field one can estimate the FAC intensity (in ID approximation). Estimates give the following values, respectively: J« ~ 0.3 цА/m2, J|| ~ 1.5 цА /т2and J|| ~ 2.1 цА /т2. The shown magnetic disturbances are recorded in the near-noon sector o f polar latitudes Ф > 75°, corresponding to the location of the NBZ (or zone 3) of field-aligned currents. Their dynamics shows that an intensity o f associated FAC increases after an arrival of each impacts. Spectrograms DMSP also show an increase in the flux of electrons with energies of 0.1-3 keV and ions with energies of 1.0-10 keV in the daytime sector o f polar latitudes after each shock. Thus, it can be assumed that the intensification o f FAC in the near-noon sector leads to the development of specific polar-latitude negative bay-like magnetic disturbances observed on the ground. Conclusions It is shown that the development o f perturbations in the high-latitude ionosphere in response to the arrival o f the shock front of the solar wind dynamic pressure Psw depends on the prehistory in the solar wind conditions. After few days of quiet solar wind, the intensive front did not lead to the development of significant disturbances. However, the like shock front, following after the two previous ones, led to the development of daytime and night substorms as well as to the beginning o f the intensive storm. Magnetic disturbances, obtained after treatment of SWARM satellites data, showed that each of the three Psw jumps led to the development of field-aligned currents with a density of ~ 1.5 pA/m2 in the near-noon sector at geomagnetic Ф - 17 Мурманская государственная областная универсальная научная библиотека