An investigation of the nature of Pc5 pulsations using SuperDARN and magnetometer data.

Abstract

Pc5 pulsations are global magnetohydrodynamic events in the magnetosphere. We employed an Automated Pulsation Finder program to identify significant Pc5 pulsation events in SuperDARN data. Those events for which a resonance of similar frequency band was observed in more than one HF radar were selected. The three events presented here are such that a similar resonance was observed in Goose Bay, Saskatoon and Pykkvibaer HF radars, located in the northern polar region. One event was isolated in which the resonance was observed at the conjugate hemisphere at Sanae, Antarctica. Those events have a good data from magnetometer chains within the field of view of HF radars are chosen for analysis. These two instruments complement each other. We combined these two instruments to investigate the nature of the pulsation, determining its qualitative polarization characteristics. Observations of a resonance that extend over a large fraction of the polar region are rarely reported. A complex demodulation technique was employed to determine the amplitude and phase relationship between field components observed by the radars and magnetometer chains, this in turn, affords resolution of other characteristics of pulsations such as wave number and phase velocity. We present results in a graphical form and discuss them in the context of MHD theory of magnetic pulsations, speculating on their generation mechanism.