SuperDARN Observations of High Latitude Electrodynamics in the Terrestrial Ionosphere

<div>Coupling of the solar wind and interplanetary magnetic field to the terrestrial</div><div>system results in a dynamic magnetosphere-ionosphere interaction, full of complexity</div><div>yet to be unravelled. In this thesis, high latitude electrodynamics will</div><div>be examined in relation to solar wind - magnetosphere - ionosphere coupling,</div><div>primarily by observations from the Super Dual Auroral Radar Network (Super-</div><div>DARN). SuperDARN is made up of, at time of writing, over 35 high frequency</div><div>coherent scatter radars, which provide near global coverage of the geomagnetic</div><div>poles. Originally conceived to measure ionospheric convection, the SuperDARN</div><div>dataset can be assimilated into minute resolution electrostatic potential solutions,</div><div>known as ionospheric convection maps, which are the primary diagnostic tool in</div><div>this thesis. The quality of the derived equipotential maps is dependent on a variety</div><div>of processing stages, including the determination of the low latitude limit</div><div>of the convection pattern. Firstly, a new method for determining the position of</div><div>this boundary is presented, based on an examination of the relationship between</div><div>the scale sizes of the convection and field aligned current (FAC) regions. A linear</div><div>relationship is demonstrated, which can be used, incorporating independent FAC</div><div>measurements, to estimate a scatter independent measure of the low latitude</div><div>limit of the convection region. Finally, the effects of the impact of solar wind</div><div>pressure pulses on the terrestrial ionosphere will be examined. If the pressure</div><div>pulse compresses the magnetosphere but does not trigger a geomagnetic storm,</div><div>this is known as a positive sudden impulse. Enhancements in dayside driving of</div><div>the ionosphere following the onset of a positive sudden impulse will be presented</div><div>both in the form of a detailed case study, and statistically using a superposed</div><div>epoch analysis. For the first time, simultaneous measurements of ionospheric</div><div>convection and FACs will be utilised to observe the effects of this phenomenon.</div>