The upper atmosphere contains a layer of conductive gas that is the D region ionosphere. The D region is affected by various sources that originate both from Earth and the lower atmosphere and also from space. Yet, there are few methods to study this region due to its altitude. This PhD sets out to improve on the existing widely used sub-ionospheric radio remote sensing method. Existing observations typically use a 20ms time resolution such that the narrowband transmissions monitored can be approximated to a single frequency. A new, 1µs time resolution technique is detailed in this thesis that is able to show the frequency response and the fast variability of the transmission propagation. The new technique was applied with transmissions at multiple frequencies yielding experimental results that (1) suggest a new mechanism of ionospheric perturbation by thunderstorm electrostatic field and; (2) provide the first observations of the frequency dependence of wide angle sprite scattering. This technique can be applied to further observations in support of the ASIM and TARANIS space missions to study upper atmospheric lightning. More generally, it can also be applied to the studies of D region processes and other sources of ionospheric perturbations.
|Date of Award||15 Jun 2018|
|Supervisor||Martin Fullekrug (Supervisor) & Robert Watson (Supervisor)|