The Role of the Boundary Layer and the Associated Physical Processes During Hot Days and Heatwaves in Southeastern Australia

This thesis explores what happens in the atmospheric boundary layer (from the surface to approximately 3 km) and how these processes contribute to heatwaves in southeastern Australia from an observational and modelling perspective. It is found that a northwesterly nocturnal jet transports warm air into the hot day region and the initially high nighttime temperatures resulting from subsidence associated with an upper-level high pressure system determine a hot day. Single hot days can turn into heatwaves when the upper-level high pressure system moves slowly over the region.