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.

Ionosphere response to the intense ULF waves as observed by GPS/TEC and EISCAT instruments 3. Oct. 31,2003 ULF event During the recovery phase of large magnetic storm on Oct. 31, 2003 very intense (up to a few hundred nT) global quasi-monochromatic Pc5 waves were observed [Kleimenova, Kozyreva, 2005]. During the periods 11.00-12.00 UT and 12.00-13.00 UT with elevated Pc5 activity, TEC fluctuations have been compared with ground geomagnetic variations at station KIR (geographic latitude 67.8°) and ionospheric parameters determined by EISCAT radar. The TEC data show gradual variations around 30-40 TECu with superposed small- scale fluctuations. To highlight these fluctuations the TEC data have been detrended with a cut-off frequency of 1 mHz. Quasi-periodic TEC pulsations have been revealed over a wide latitudinal range. Figure 1. Pierce points at 250 km altitude of radio paths from GPS satellites GPS7, GPS9, and GPS28 to ground receivers KIRU (violet line), VARS (orange line), and TROM (green line) in Scandinavia during Oct. 31, 2003, 11.00-11.30 UT. Magnetometers are denoted with triangles, GPS receivers are denoted with squares, riometer KIL is marked with asterisk, and EISCAT is shown by dark circle. Figure 2. Multi-instrument observations of Pc5 waves during Oct. 31, 1100-1330 UT. From lop to bottom: X-component (in nT) of geomagnetic pulsations at KIR; detrended (with a 1 mHz cut-off frequency) TEC fluctuations (in TECu) along radio paths GPS07/KIRU (dotted line) and GPS09/KIRU (solid line); EISCAT Ne fluctuations at h=110 km; and cosmic noise absorption from KIL riometer. 11.00 11.30 12.00 12.30 13.00 13.30 UT The comparison for the period 11.00-13.30 UT of TEC fluctuations along paths GPS7/KIRU, GPS9/KIRU with magnetic variations at KIR and EISCAT-derived ionospheric density Ne in the lower ionosphere, shows the occurrence of persistent periodicity in all these parameters (Fig. 2). The peak-to-peak amplitudes of oscillations of the TEC are A N j ~0.6 TECU (GPS07/KIR), and -1 .0 TECU (GPS09/KIRU), and magnetic pulsations ДВ-400 nT 31 October 2003, 11.00-11.30 UT H 200 X 100 Tс 0 u 5 -100 S> -200 1 -300 0.6 ja 0.4 ы 0.2 g 0 0 E- -0.2 -0.4 - 0.6 2.5x10" t E 2 . 0 x 10 " i 1.5x10" J 1,0x10" 5.0x10'“ g 0 4 0.3 0.2 0.1 0.0 31 O c to b e r 2 0 0 3 41