Dynamics, Variability and Impacts of the Southern Hemisphere Winter Subtropical Jet

The subtropical jet stream in the upper troposphere over Australia is an important feature of Southern Hemisphere climate during winter. However, there is little understanding of the causes of its year-to-year variability and its role for influencing interactions between the tropics and other regions. This thesis used observational datasets to reveal how variability in the tropical oceans and mid-latitude weather systems impact variations of the jet stream. A range of climate model experiments were also designed that highlighted the importance of the subtropical jet stream in shaping the atmospheric circulation response to tropical Pacific and Indian Ocean atmospheric heating.