Impacts of Geomagnetic Disturbances on the Low- and Mid-Latitude lonosphere over Australia
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Date
2024
Authors
Camilleri, Tristan Anthony
Editors
Advisors
Cervera, Manuel
Ward, Bruce
Mackinnon, Andrew
Ward, Bruce
Mackinnon, Andrew
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Abstract
The ionosphere is an ionised region of the Earth’s upper atmosphere which can be used to refract high frequency radio waves, facilitating long-range radio communication and over-the-horizon radar. Space weather events which lead to geomagnetic disturbances can influence and disturb the ionosphere, altering its strength and structure for several days. This alters the ionosphere’s refractive properties, and thus has implications for the performance of high frequency systems. The effects of geomagnetic storms can be characterised by the modelling of parameters such as the strength of the ionospheric equatorial electric field and the vertical plasma drift velocities in the equatorial ionosphere. The response of the ionosphere can also be observed through the changes in the electron number density and height of the peak electron number density over a region of the Earth. A new model was created which uses ground-based magnetometer data from Thailand and the Phillipines to predict the vertical plasma drift velocity in the equatorial ionosphere, which will influence the ionospheric plasma transport mechanisms over northern Australia. This was used concurrently with an existing ionospheric equatorial electric field model and data from the Jindalee Operational Radar Network (JORN) and Australian Bureau of Meteorology high frequency ionospheric sounder networks to analyse the response of the ionosphere over Australia to geomagnetic storms in March 2015, June 2015, October 2016, and September 2017. The new equatorial ionospheric vertical plasma drift velocity model was developed from magnetometer and ionospheric drift velocity measurements from the Jicamarca Radio Observatory, Peru. It was found to produce a significant improvement in accuracy over existing models in the literature. Interplanetary parameters and global magnetic indices were also used to characterise the geomagnetic disturbances. It was found that the ionospheric response over Australia to geomagnetic disturbance is strongly dependent on electrodynamic processes, neutral atmospheric conditions, and the preconditioning of the magnetosphere-ionosphere-thermosphere system.
School/Discipline
School of Physics, Chemistry and Earth Sciences
Dissertation Note
Thesis (MPhil.) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences, 2024
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This thesis is currently under embargo and not available.