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.

Geomagnetic and ionosphere TEC response to the abrupt increase o fsolar wind density In the evening sector (Scandinavia), vTEC variations have been constructed for different radiopaths between available GPS satellites and KIRU receiver. At a background of gradual increase of vTEC, a superposed positive pulse of vTEC is observed with amplitude up to AN t ~ 1 TECu (Fig. 4). The ЛТЕС/ТЕС in the dusk sector is less than the 10%. Onset of TEC growth coincides with PI at station KIR, but no PI signatures can be seen in TEC. The impulsive TEC enhancements coincide with the geomagnetic MI at KIR. The observed ionospheric response may be caused by plasma compression, additional ionization due to the electron precipitation, or ionospheric plasma redistribution owing to the wave electric field. The vertical structure of the ionospheric disturbance can be determined with incoherent radar. 5. EISCAT radar response to SC. Incoherent radar EISCAT in Tromso provides a vertical profile up to 200 km of main ionospheric parameters with cadence 1 min. The EISCAT-measured electron density Ne evidently shows an impulsive response to SC (Fig. 5). At the same time, no clear signatures in ionospheric E-field coherent with magnetic disturbance are observed. EISCAT reveals an irregular increases of Ti and Tc at altitudes >150 km. Most evident response in electron density Ne can be seen at altitudes 110-170 km (Fig. 5). A growth ofNe in the E-layer (120 km) starts simultaneously with riometer increase and PI. The increase of Ne from 10 10 m '3 to 1.7 10um "3 reaches maximum simultaneously with MI peak, but decays during the period ~2 min that is longer that the duration of MI ~ 1min. 6. Discussion and conclusions. The analysis of SC event recorded simultaneously by various instruments on the ground and in space has shown a surprisingly large variety o f associated effects. Only latitudinally localized transient Pc5 pulsations at the dawn and dusk flanks have been observed, which correspond to the independent response of resonant field lines in the morning and evening sectors [Samsonov et al., 2011]. The lack of oscillatory response at Ф~ 66 ° is probably caused by the plasmapause, because in its vicinity the radial gradient of Alfven period Тл(Ф) becomes smooth. Therefore, a mode conversion into Alfven oscillations of geomagnetic shell is weak in this region. Clear resonant transient Psc5 oscillations are independently generated on the morning and evening flanks, no signatures of theoretically predicted cavity mode excitation is found. In this study, for the first time (to the best of our knowledge) a TEC response to SC was found. A responsible mechanism of TEC modulation may be related to field-aligned plasma transport by Alfven pulse, which provides an additional plasma flow in the bottom ionosphere. During the SC event under examination, the path-integrated electron density TEC, response to MI only has been detected. The modulation of the ionospheric plasma density may be caused by the interaction of an incident MHD pulse with the ionosphere - atmosphere - ground system. Shear Alfven wave does not produce plasma/magnetic field compression, so any compressional effects arise upon interaction of this mode with the anisotropic inhomogeneous ionosphere. A precipitation of energetic electrons and ionization of the lower ionosphere during SC recorded by riometers can influence bottom E-layer and D-layer which contribution into TEC is small. Nearly simultaneous response in riometer, TEC, and EISCAT Ne may be interpreted as a stimulated by SC precipitation of electrons with a wide energy range, from soft (<keV) to energetic (tens of keV). Acknow ledgements. This research is supported by grants from RFBR № 16-35-60049 mol a_dk (VB) and No 15- 45-05108 (SS), grant No 16-17-00121 from RSF (VP), and the grant No 246725 from the Norwegian Research Council (DL). The geomagnetic activity and solar wind data were obtained from OMNIWeb facility ( omniweb.gsfc.nasa.gov ). The authors acknowledge the open data policies of CARISMA ( gsc.nrcan.gc.ca/geomag ). References - Araki T. A physical model of the geomagnetic sudden commencement, in: Solar Wind Sources of Magnetospheric Ultra-Low- FrequencyWaves, Geophys. Monogr. Ser., 81, ed. by M. J. Engebretson, K. Takahashi, and M. Scholer, AGU, Washington, D. C., 183. 1994. - Belakhovsky V., V. Pilipenko, D. Murr, E. Fedorov, and A. Kozlovsky. Modulation of the ionosphere by Pc5 waves observed simultaneously by GPS/TEC and EISCAT // Earth Planets Space. 68 : 102. doi: 10.1186/s40623-016-0480-7. 2016. - Fujita S., T. Tanaka, T. Kikuchi, K. Fujimoto, K. Hosokawa, and M. 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