Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

V. Filipenko et al. 31 October 20»:j I ,R0 ж ■««. ■ :«X) ti S at*-? V ' i W/| b r l 1 .... ........I l J : : L jr S o t - } ) Ш Ш wW * M h p w i Щ № V '■■ khh 'h j ,V : .03 JJ.3C 1ЦЛД* Г-i^-i 13.1=0 l»aO M.flC Fig. 2 Panels a and b: detrended TEC data with a high-pass filter (1 mHz cut-off frequency) along radio paths between S07 and S09 and KIR. TEC variations are measured in TEC units. Panel с: X- component (in nT) geomagnetic pulsations at KIR. ! AIK t юг :ll O ctotw r SUWI ft h i Л A l l t i d i\ i L h J 1, U! И Г f W P 5Г|- v | II I | V * 1 j Ш Ш Ш "I / Y V. ¥ ; if ^ ! % M I it oo iii.» п.го ti-20 j 140 j i so <гос Fig. 3 Upper panel: Superposed magnetic variations (X-component) with 30-s cadence at longitudinally separated stations KIR (red) - LOZ (red); Bottom panel: Superposed TEC variations with 30 s cadence along longitudinally separated radio paths from S7 (black) and S9 (red) to GPS receiver at KIR. perturbation. Variations in TEC along the signal propagation through the ionosphere. For the order the characteristic thickness of F-layer. ionospheric plasma are ANT —0.6 (S07/KIR), ~2.0 (S14/KIR), and -1 .0 (S09/KIR), and magnetic pulsations -4 0 0 nT at KIR. TEC quasi-periodic pulsations are observed over a wide latitudinal range. The typical frequency o f TEC pulsations at different latitudes is nearly the same, —2.4 mHz. The cosmic radio noise absorption, measured by the multi-beam IRIS riometer at KIL, does not demonstrate the periodicity evident in magnetometer and TEC data. Cross-spectral analysis confirms the good correspondence of both TEC and В variations. During the 1130-1300 UT time interval the coherency between TEC (S-09/KIR path) and X- component magnetic fluctuations at f~2.5 mHz is rather high, y~0.8. The ratio between the spectral densities o f TEC ANT and magnetic Д В variations at this frequency is ANj/AB ~ 2x 1 0 3 TECU/nT. This ratio is in accord with typical amplitude of TEC oscillations, -1 TECU, and magnetic pulsations, -4 0 0 nT. The superposition o f TEC data from different satellites shows a good coherency between these fluctuations. We tried to estimate the azimuthal propagation characteristics o f TEC variations using different radio paths for the same GPS station. Fig. 3 shows the superposed TEC fluctuations from S7 and S9 satellites for KIR. The same figure shows the superposed magnetic variations at stations KIR-LOZ, longitudinally separated by ДЛ~11.9°. Cross-correlation analysis reveals between KIR-LOZ a time shift Дт-20 s. For the wave frequency f ~3 mHz, this time shift corresponds to the azimuthal wave number m - 1.8. However, a similar analysis did not reveal a time shift for the TEC variations A t - 0 s. Probably, this result is related to the low cadence o f TEC data (30 s). Therefore, comparison of longitudinally separated TEC data provides only the upper limit on a m-value: for Дт<30 s m<2J. Theoretical estimates The determination o f an apparent impedance o f global Pc5 waves, using the combined SuperDARN and magnetometer data, demonstrated that these waves are predominantly composed o f Alfven waves [Pilipenko et al., 2012]. Therefore, it is necessary to consider possible mechanisms o f Alfven wave impact on the ionosphere-magnetosphere plasma. Nearly 90% of TEC is provided by the ionospheric plasma at altitudes less than 103 km. The temporal variations in the TEC evaluated along the line between a source (S) and receiver (R) is given by d ,N T = d tN d z . Variations o f local plasma density N are described by the continuity equation dN — = - V W - N V V + Q - L (1) where Q and L are the electron production and loss rates respectively and V is the plasma velocity from the ULF path introduce time/phase delays for high frequency radio wave o f magnitude estimate we suppose that N T - N A z , where Аг is Possible mechanisms Wave modulation. Among possible MHD waves in a cold plasma, the AlfVen mode does not perturb the plasma density. The plasma oscillations in a fast mode are of the same relative amplitude as oscillations o f the magnetic field, that is AN/NZAB/B. Thus, it seems that toroidal Pc5 waves cannot directly modulate the ma-netospheric plasma density. ° F 78