Slow magnetosonic oscillations with m 1 in a dipole magnetosphere with rotating plasma

Abstract

[1] A mechanism of excitation of azimuthal small-scale (m 1) slow magnetosonic (SMS) oscillations by the external currents in the near-equatorial region of the terrestrial magnetosphere is proposed. A theoretical study of the structure and spectrum of such oscillations is performed in the model of the magnetosphere with the dipole magnetic field and rotating plasma. In the direction along field lines of the geomagnetic field the oscillations are waves standing between the magnetically conjugated points. The amplitude of the magnetospheric SMS oscillations with m 1 decreases from the equatorial plane to the ionosphere at scales much lower then the field line length. So one is not able to observe the SMS-oscillation field in the vicinity of the ionosphere and on the surface of the Earth. In the direction across the magnetic shells, the standing SMS waves have a structure typical for resonant oscillations. Latitudinal distributions of eigenfrequencies of several first harmonics of SMS oscillations with the polarization similar to the polarization of poloidal and toroidal Alfven waves in the plane perpendicular to the field lines are drawn. INDEX