Spectral and Polarization Characteristics of Pc 3-5 Magnetic Pulsations Observed at the Syowa Station-Iceland Conjugate Pair (d. ULF Waves in the Magnetosphere) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and Magnetosphere in the Polar Regions : Part I)

Abstract

From the magnetic pulsation data recorded at the Syowa Station-Iceland conjugate pair, it is found that there are at least two pulsation bands in the Pc 3-5 frequency range in the daytime. 0ne pulsation band occurs in the 20-40 mHz range, while the other band occurs in the 4-8 mHz range, often independently of the 20-40 mHz band. The f-t spectral patterns of these pulsations are quite similar at the coniugate points, with the wave phase characteristics of odd-mode standing oscillations of local magnetic field lines. It is also found that the orientation angles of the polarization ellipses in the H-D plane switch across the magnetic local noon. These results suggest that the 20-40 mHz band and the 4-8 mHz band are standing oscillations of resonant field lines excited by external driving forces such as the Kelvin-Helmholtz instability on the magnetopause and/or the MHD waves generated near the bow shock