Иркутск, Россия
In the paper, we examine the spatial structure of eigenharmonics of the poloidal Alfvén resonator recorded by the RBSP-B satellite on 23 October 2012 at 19:12–20:24 UT. We employ the method of phase portraits, which is a set of plots of magnetic/electric field components of oscillations as well as the phase shift between transverse components, to interpret the data. Based on the theoretical description of magnetospheric MHD waves, an analytical solution for eigenharmonics of the poloidal Alfvén resonator is framed. The phase shift of individual harmonics of the observed oscillations is shown to have a quasi-periodic structure, which allows us to confirm that they have resonator modes, and the magnetic field components analytically calculated along the satellite trajectory qualitatively coincide with the satellite data. From comparison of theoretical calculations of the structure of transverse magnetic field components with observational data, we put forward an assumption that the second and fourth harmonics of the poloidal resonator make the main contribution to the observed oscillations.
Alfvén waves, poloidal resonator, ULF waves, satellite observations
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