Continuous Pulsation Dynamics in the High-Latitude Magnetosphere-Ionosphere System

The thesis investigates Ultra Low Frequency waves in the band 0.1 Hz to 5 Hz in the terrestrial magnetosphere-ionosphere system. Utilising mid-high latitude ground-based induction coil magnetometers, continuous (Pc1-2) and irregular (Pi1-c) pulsations are explored through the application of digital spectral analysis. An assessment of two spectral analysis techniques is conducted. From which it is concluded that, for routine ground-based analysis of Pc1-2 pulsations, treating the horizontal components of magnetic field variation as a single complex signal is computationally beneficial with minimal loss of useful information. Polarisation parameters and values of cross spectral phase are derived using a weighted histogram technique and are subsequently used to distinguish discrete pulsations and infer their location through simple triangulation. The results of a statistical study of ~1200 discrete Pc1-2 events over the full year of 2007, during the declining phase of solar cycle 23, are presented. This study, for the first time, reports the ground-based polarisation properties of Pc1-2 waves as a function of latitude. The derived diurnal frequency behaviour supports the suggestion that the Ionospheric Alfvén Resonator may play a part in the filtration of ground-based Pc1 observations. Pc1-2 behaviour over the course of 26 geomagnetic storms is also presented, with support being found for the association of pulsation enhancement with plasmaspheric plume formation in the recovery phase. A case study, combining coherent and incoherent radar, in situ particle measurements and ground based magnetometry, has focused on high latitude Pi-c activity during a period of enhanced dayside reconnection. This study has provided support for the association of Electromagnetic Ion cyclotron waves with the SuperDARN spectral width enhancements observed in the flanks of the ionospheric cusp.