Discrete Spectral Structure of Low-Latitude and Equatorial Pi2 Pulsation
1992 Volume 44 Issue 3 Pages 253-259
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1992 Volume 44 Issue 3 Pages 253-259
A Pi2 event observed simultaneously at three low-latitude and equatorial stations is analyzed using a new maximum likelihood method, and found to be mathematically composed of multiple exponentially damped sinusoids, of which frequencies are almost identical at the three stations. This is a piece of evidence to support the existence of the global mode cavity resonance. A numerical eigen-mode analysis of the decoupled poloidal wave equation with the outer boundary of the cavity located at the plasmapause can not sufficiently explain the observed discrete frequencies of the Pi2 event, so that the global cavity with the outer boundary outside the plasmapause is inevitably invoked.
