Geomagnetic disturbances and pulsations as a high latitude response to considerable alternating IMF variationsduring the magnetic storm recovery phase (May 30, 2003)статья
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Аннотация:Singularities of high-latitude geomagnetic disturbances during the magnetic storm recovery phase (Dstmin = –144 nT) were studied based on the observations on the Scandinavian profile of magnetometers (IMAGE). Certain atypical effects that occur under the conditions of large positive IMF Bz values (about +20–25 nT) and large negative IMF By values (to –20 nT) were revealed. Thus, an intense (about 400 nT) negative bay in the field X component (the polar electrojet, PE) was observed in the dayside sector at geomagnetic latitudes higher than 70°. As the IMF By reverses its sign from negative to positive, the bay in the magnetic field X component was replaced by the bay in the field Y component. The possible distribution of the field-aligned currents in the NBZ system was analyzed based on the CHAMP satellite data. The results were compared with the position of the auroral oval (the OVATION model) and the ion and electron flux observations on the DMSP satellite. Analysis of the particle spectra indicated that these spectra correspond to the auroral oval dayside sector crossings by the satellite, i.e., to the dayside projection of the plasma ring surrounding the Earth. Arguments are presented for the assumption that the discussed dayside electrojet (PE) is localized near the polar edge of the dayside auroral oval in a closed magnetosphere. The singularities of the spectral and spatial dynamics of intense Pc5 geomagnetic pulsations were studied in this time interval. It was established that the spectrum of high-latitude (higher than ~70°) pulsations does not coincide with the spectrum of fluctuations in the solar wind and IMF. It was shown that Pc5 geomagnetic pulsations can be considered among resonance oscillations at latitudes lower than 70° and apparently reflect fluctuations in turbulent sheets adjacent to the magnetopause (the lowlatitude boundary layer, a cusp throat) or in a turbulent magnetosheath at higher latitudes.