Affiliation:
1. Institute of Solar Terrestrial Physics SB RAS
2. Institute of Solar-Terrestrial Physics SB RAS
Abstract
We continue to study the physical processes occurring during the August 17, 2001 magnetospheric storm by analyzing the dynamics of the intensity of field-aligned currents (FACs) in Iijima—Potemra Region 1 in the polar ionospheres of two hemispheres, using the modernized magnetogram inversion technique. The results obtained on the dynamics of the FAC asymmetry of two types (dawn–dusk and interhemispheric), as well as the previously obtained regularities in the behavior of Hall currents and polar cap boundaries depending on the large azimuthal component of the interplanetary magnetic field (IMF), observed during the storm, and the seasonal behavior of the conductivity are consistent with the open magnetosphere model and with satellite observations of auroras in two hemispheres. We have shown that the weakening of the asymmetry of two types in the FAC distribution during substorms in the storm under study occurs almost completely in the winter hemisphere and is much weaker in the summer one. We associate this phenomenon with the predominance of the effect of long-term exposure to the azimuthal IMF component in the sunlit polar ionosphere of the summer hemisphere over the substorm symmetrization effect of the night magnetosphere. A symmetrization effect of the polar cap and FACs, created by the solar wind pressure pulse at the end of the storm, is observed. We propose a qualitative explanation of this effect.
Publisher
Infra-M Academic Publishing House
Reference49 articles.
1. Бороев P.H., Гельберг М.Г. Зависимость долготной локализации центра суббури на геосинхронных орбитах от Ву-компоненты ММП // Геомагнетизм и аэрономия. 2001. Т. 41, № 5. С. 588–594., Atkinson G., Hutchison D. Effect of the day night ionospheric conductivity gradient on polar cap convective flow. J. Geophys. Res.: Space Phys. 1978, vol. 83, no. A2, pp. 725–729. DOI: 10.1029/JA083iA02p00725.
2. Величко В.А., Бороев P.H., Гельберг М.Г. Азимутальная асимметрия областей втекающих и вытекающих из ионосферы продольных токов в токовом клине суббури // Геомагнетизм и аэрономия. 2002. Т. 42, № 5. С. 619–623., Benkevich L. Effects of ionospheric conductance in high latitude phenomena: PhD Thesis, University of Saskatchewan: Saskatoon, Canada, 2006, 210 p.
3. Ляцкий В.Б. Токовые системы магнитосферно-ионосферных возмущений. Ленинград: Наука, 1978. 199 c., Benkevich L., Lyatsky W., Cogger L.L. Field-aligned currents between conjugate hemispheres. J. Geophys. Res.: Space Phys. 2000, vol. 105, no. A12, pp. 27727–27737. DOI: 10.1029/2000ja900095.
4. Ляцкий В.Б., Мальцев Ю.П. Магнитосферно-ионо-сферное взаимодействие. М.: Наука, 1983. 192 с., Boroev P.H., Gelberg M.G. Dependence of the longitudinal localization of the substorm center in geosynchronous orbits on the IMF Vy component. Geomagnetism and Aeronomy. 2001, vol. 41, no. 5, pp.588–594. (In Russian).
5. Мишин В.М. Спокойные геомагнитные вариации и токи в магнитосфере. Новосибирск: Наука, 1976. 203 с., Cowley S.W.H. Magnetospheric asymmetries associated with the y-component of the IMF. Planet. Space Sci. 1981, vol. 29, no. 1, pp. 79–96. DOI: 10.1016/0032-0633(81)90141-0.