Physics of auroral phenomena : proceedings of the 34th Annual seminar, Apatity, 01 - 04 March, 2011 / [ed.: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 231 с. : ил.

N.A. Barkhatov et al. 15 14 13 Q) " 11 a) 12 С 0) и 10 • 8 в 1 5 0 2 0 0 time, minutes b ) time, minutes Fig. 1. a - geomagnetic storm main phase recorded at the station Kevo 18.04.2001, b - «wavelet skeleton» form or so-called local maxima graph for Fig. la The results of the post-processing for wavelet transforms have the following interpretation. Skeleton of the first type «|» is very rapid process of change fluctuations state are shows. At the high-latitude stations under auroral oval this type of skeleton moving boundary between the polar cap and the auroral oval are registered. At sub-auroral stations such skeleton the boundary between auroral oval and sub-auroral region are corresponds. Skeleton of the second type «/» is process of fluctuations energy dissipation with transition from high-frequency pulsations to low- frequency range are corresponds. It may indicate a decrease in the level of energy introduced into the oscillating system from an external source. Skeleton of the third type «\» is process of pumping the fluctuations energy to the transition from a range of low-frequency pulsations to the range of high frequency are corresponds. It may indicate an increase in the level of energy introduced into the oscillating system from an external source. Nonexistence the skeleton in the given time interval a steady state fluctuations are not released in amplitude and frequency in the investigated range of the scale coefficients (frequency range) can be interpreted. Features of geomagnetic storms based on wavelet analysis of skeletons Postprocessing of wavelet transforms to the analysis of magnetograms from stations IMAGE network with the aim of identifying different strength of the magnetospheric disturbances are applied. According to the results of parallel analysis of the dynamics of skeletons magnetograms classification of geomagnetic disturbances in the period range Pc4-5 registered at the stations along the northern part of the geomagnetic meridian is made. At the same time characteristic features of geomagnetic disturbances arising from the growth of different strength magnetospheric storms is revealed. It is noticed that the main features of skeletons corresponding to the geomagnetic disturbances of varying intensity in the main phase of storms has manifested. For the first group of space-time properties of disturbances, corresponding to weak and moderate storms (Dst > -100 nT) during the three hours before and during the initial phase, disturbances at low-latitude subauroral stations of network are characterized. On the main phases of storms observed extension of registration region with other skeletons (the other frequency dynamics) to the south from high-latitude stations. Characterized by a clear separation groups of skeletons in the north (the zone of the polar cap and auroral oval) and southern (sub-auroral zone). This phenomena simultaneously with an increase the diffuse auroral region is registered with respect PGI RAS model ( . For the second group of space-time properties of disturbances, corresponding to strong storms (Dst> -200 nT), different dynamics at subauroral latitudes before the initial phases are characterized. For the initial and main phases disturbances with the same dynamics are amplified simultaneously with auroral oval expansion with respect PGI RAS model. At the same time visibly display at least three groups of skeletons (the polar cap, oval, sub-auroral zone). Disturbances at high-latitude stations do not have a stable dynamic of frequency pattern in the geomagnetic storm evolution process. For the third group of space-time properties of disturbances corresponding to extreme storms (Dst <-200 nT), increased amplitudes of disturbances at the high-latitude stations even before the initial phases is characterized. The initial phase characterized by the appearance of disturbances with the same dynamics in subauroral regions. At this time the deformation of the polar cap and its shift to the night side in progress [Galperin and Feldsiein, 1996]. On the main phases of storms on the low-latitude stations of network observed the appearance of disturbances with different frequency dynamics (skeletons) followed by an extension of the auroral oval and/or diffuse auroral region. 40