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.

Т. V Kozelova and В. V. Kozelov At —22:26 UT the auroral surge (patch-like) appears near the 68° and the 32° longitude, which brightened and propagated eastward along the poleward border of the diffuse aurora. At the interval 22:26-22:35 UT the eastward expanding aurora! (EEA) structures appeared in a sequence such that each new patch formed a little to the east o f the previous one. These patches have the same signature as the azimuthally-spaced auroral forms (AAFs) reported by Elphinstone et al. (1995) and the EEAS (the eastward-expanding auroral surges) reported by Tanaka et al. (2015). Such intensified auroral patches were presumably associated with small-scale upward FAC structures in the postmidnight sector and usually observed after onset o f substorm explosive phase ( Wild and Yeoman, 2000). The EEA structures originate an undulation of the poleward border of the diffuse aurora, which observed usually during the omega bands in the post-midnight sector of the auroral zone during the recovery phase o f a substorm ( Liang et al., 2005; Tanaka et al., 2015). Note, that North-South-aligned auroras and pulsating aurora were observed in the diffuse aurora after the passage o f the EEA structures in our event after 22:27:40 UT. Besides, at -22:26 UT in addition to bright EEA structures, the discrete auroral structures appear from the west along the higher latitude (69°), which also northward and eastward expanded as in cases reported by ( Connors and Rostoker, 1993, Opgenoorth et al., 1994, Connors et al., 2003). During this activation A3, the footprints o f the THD were located westward the Apatity and outside the field o f view of Apatity all-sky camera, near equatorial border of the pulsating diffuse auroras. THEMIS D November 14, 2014 20:30 21:00 21:30 22:00 22:30 2. Magnetospheric observations 2.1 Particle fluxes and fields. Fig. 3 shows the magnetic and electric fields evolution at THD at the interval 20:30 - 23:00 UT from top to bottom: i) inclination angle o f the magnetic field relative to the XY plane; ii) Л'2-like fluctuations o f the magnetic field calculated as the deviations o f observed magnetic field from 108-seconds smoothed values, the most appreciable dBz component o f the magnetic field is shown here; iii)-iv) Ex and Ey components o f the electric field. From Fig. 3 one can see, that the times of auroral activity enhancement coincide with the times of large-scale dipolarizations o f the magnetic field, the increased dBz pulsations in the Pi2 range and the enhancement of electric field fluctuations. Before ~21:15 UT, the inclination angle o f the magnetic field decreases in an association with a decline of previous substorm at AMD. After this Figure 3. THD satellite data o f magnetic and electric fields on Nov 14, 2014 (details in text). moment, weak activations Al and A2 were accompanied by the slow large-scale dipolarization in the magnetosphere at 7.6-8.5 Re. More intense activation A3 occurs, when the THD observed the final sharp large-scale dipolarization in the magnetosphere at -7.2 Re, when the THD footprint was located near equatorward edge o f diffuse aurora. 2.2 Wave activation. Fig. 4 presents the THD observations of the particle flux and the waves (from top to bottom): i) FBK wave data for electric and magnetic fields; ii) total magnetic field; iii) electrons registered by ESA and SST detectors (< 30 keV and > 30 keV); iv) three components of plasma flows. Two bottom panels present two magnetograms from LOZ and AND. Fig. 4 shows that all three activations Al -A3 are characterized also by the variations of plasma flow velocity with periods which decrease from -10 min during Al to - 2 min during A3 (Fig. 4). As a whole, it can be seen that the values of azimuthal velocity (vv, >0 - westward) were higher than the plasma velocity in the radial direction (vx, > 0 - Earthward). But during A3, the plasma velocity burst (vn - -80 km/s) in the tailward radial direction ( v „ < 0) was observed near the moment h, when the poleward auroral boundary expanded to the north. The character of the energetic electron injections registered during the activations A l -A3 was different. During the Al and A2, the <100 keV electron injections were observed with the energy-time dispersion. The more energetic (>100 keV) electron injection appears without dispersion during the A3, what can suggest that this injection without dispersion was located near a particle injection source. During the activation A3, when the footprints of THD were located within pulsating diffuse auroral region, the low- energy electron flux (0.1 -3 keV) bursts were observed by the THD. These bursts have the quasi-period - 60-90 s and occur at the moments of small-scale local dipolarizations, simultaneously with the enhanced ELF wave bursts at frequencies below 100 Hz observed by THD. The wave features are more visible in the electric field data. The electrostatic cyclotron harmonic (ECH) waves are observed as discrete intensity enhancements at -10-200 Hz. The electric field wave power tends to increase during the activity A3, when the auroral intensity is large. The discrete intensity ECH enhancements coincided with the DC electric field variation (the details are not shown). 32