Fine structure of Pi2-type geomagnetic pulsations

Influence of anomalous particle diffusion on the current system formation and coherence of Pi2 geomagnetic pulsation local ionospheric sources

“…We use an analysis of the events of Pi2 geomagnetic pulsation generation at 1830-1900 UT on July 9, 1998 (Petlenko et al, 2011a). We represent the Pi2 field variation dynamics as distributions of the Z vertical component filtered by selective equal band optimal filters with FIR of equal lengths and filtering periods of 120, 130, 140, and 150 s. We use only this representa tion, since the Z component distribution features ade quately reflect specific features of the vector distribu tion represented by the X andY field components.…”

“…We represent the Pi2 field variation dynamics as distributions of the Z vertical component filtered by selective equal band optimal filters with FIR of equal lengths and filtering periods of 120, 130, 140, and 150 s. We use only this representa tion, since the Z component distribution features ade quately reflect specific features of the vector distribu tion represented by the X andY field components. We constructed the distributions using the data from 47 BEAR stations, the coordinates of which are pre sented in (Petlenko et al, 2011a), with the 10 s data dis cretization interval on the grid including 100 × 81 equally separated nodes.…”

“…1 are explained by the possible branching of the field aligned currents of their 3D current system (Petlenko et al, 2011a), which is characterized by: (a) the stabi lization of the stationary source positions during the Pi2 half period and their possible random ~100 km displacements; (b) rapid nonstationary field "recon structions" during short (~1/3 half period) periods; (c) the presence of synchronization instants, when the stationary source intensity stops redistributing during the Pi2 half period and pulsed variations (upsets) in the phase of their oscillations are registered. Instants 1857:20 and 1858:40 UT are characterized by intensi fication of the sources in the western zone of the Pi2 generation region.…”

“…An analysis of the Pi2 field, performed based on the data from the BEAR denser network of magnetome ters (Petlenko et al, 2011a), made it possible to detect the high latitude Pi2 field fine structure and to explain the observed delays by the fact that the Pi2 local iono spheric source intensity is redistributed over not more than the pulse half period. These sources are consid ered as Hall currents localized in the ionosphere, the positions of which remain almost stable during a Pi2 train.…”