Abstract

In 27 October 2012 the ULF wave in Pc4 range being Alfv'en wave was observed with Van Allen Probe A. In the event the parallel Poynting flux of the wave was directed towards the Northern ionosphere. Assuming that this may be caused by the asymmetry of ionospheric conductivity between the Northern and Southern hemispheres, its effect on the standing structure of the Alfv'en wave was investigated in this paper. For this purpose the analytical model with straight magnetic field lines was used. As a result the method for estimation of the Northern and Southern ionospheric conductivity was developed. It allows us to reconstruct the parallel structure of Alfv'en waves under various conditions of the ionospheric conductivity. With the method developed, the ionospheric conductivity for the October 27, 2012 event was evaluated and compared with ionosphere model IRI-2016.