Physics of auroral phenomena : proceedings of the 39th annual seminar, Apatity, 29 February-4 March, 2016 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2016. - 167 с. : ил., табл.

V. Pilipenko et al. (X-component) at KIR. Visual inspection of Fig. 2 shows that magnetic (X-component) and TEC variations are approximately out-of-phase. At the same time, the riometer data do not demonstrate the periodicity evident in magnetometer data (bottom panel in Fig. 2). Spectral analysis confirmed the occurrence of the same periodicity with /~ 2.4 mHz in variations o f the geomagnetic field, TEC (GPS07, GPS09), and EISCAT Ne [Pilipenko et al., 2014b]. Cross-spectral analysis also showed a good correspondence between TEC and В variations. During the 11.30-13.00 UT time interval the spectral coherency of TEC fluctuations at GPS09/KIRU and magnetic pulsations at KIR around the frequency 2.5 mHz was high, y(/)~0.8. The ratio between the spectral densities of TEC and A'-component magnetic variations at this frequency was ANT(f)/AB(f) ~ 2 10'3TECu/nT. Magnetic pulsations (X-component, KIR) and EISCAT electric field Ex had coherency y~0.8. The cross-correlation between TEC variations from GPS09/KIRU and EISCAT field Ex had a high coherency y(/)~0.86. The ratio between spectral amplitudes at this frequency was АЛгт(/)/£'х(/)~4 10'3 TECu/(mV/m). An important parameter of ULF wave structure is its scale in the latitudinal (radial) and longitudinal (azimuthal) directions. The longitudinal propagation characteristics are characterized by the azimuthal wave number m, which can be determined from a cross-correlation time shift Ax between two detrended time series with periodic variations with period T at sites separated in longitude by AA, as follows m=(At/7)(360°/AA). The cross-correlation function R ( Ax) for magnetic and TEC variations has been estimated using the magnetic stations KIR-LOZ at latitude -67.8°, longitudinally separated in geographic coordinates by AA~15.4°, and the longitudinally separated pierce points along receiver/satellite paths TROM/GPS9 and VARS/GPS28 at geographic latitude -69.7° and separated in longitude by AA=27.2°. For the wave frequency/-2 .5 mHz the azimuthal wave number m ~ 0.9 for magnetic data, m ~ 0.5 for TEC data. Thus, though both magnetic and TEC data show a Pc5 wave propagation in the same direction, the m-values from ionospheric TEC data are somewhat lower than those from ground geomagnetic data. 31 October 2003 500 8 * 10 " 1 400 J 2 300 •gj M Ш^ Jj 200 3*10“ 100 8.60 p 5.68 оu 6 4.75 sn a V Q 3.83 2.91 80 ё 6 8 *«n v ® 59 51 11.00 11.10 11.20 11.30 11.40 11.50 12 00 UT Figure 3. Time variations of the EISCAT electron density during 2003, Oct. 31, 11.00-12.00 UT: (upper panel) altitude-time plot; (middle panel) Ne variations altitude-integrated over altitude range 103 - 152 km (in TECu) and superposed TEC variations from GPS9/KIRU; (bottom panel) Ne variations altitude-integrated over altitude ranee 152 - 415 km (in TECu) and superposed vTEC variations GPS9/KIRU. To find out which altitudes contributes most to the TEC variations, we have integrated ionospheric Ne(z) data from EISCAT over two different altitude range: the bottom ionosphere from 103 km to 152 km; and the F-layer from 152 km to 415 km. Comparison between height-time diagram of Ve(r) variations, and altitude-integrated ionospheric densities <Ne> (in TECu) are compared with actual TEC variations for two time intervals- 11 00-12 00 UT (Fig. 3). Comparison of these fluctuations with periodic variations of TEC shows that main contribution is provided by lower ionosphere, up to -150 km (that is the E-layer and lower F-layer). 42