Tropical cyclone tracks in CMIP5 models : statistical assessment and future projections

Tropical cyclones (TCs) can have devastating social and economic impacts on coastal communities situated all around the globe. The impact of anthropogenic induced climate change on TC activity has attracted widespread scientific interest over the past decade, resulting in the development of a variety of approaches for TC projection in climate models. However, many uncertainties remain, including those associated with the TC detection algorithm and climate model inter-dependencies that impact projection results. This thesis seeks to address these uncertainties, as well as filling several knowledge gaps in the literature such as limited TC projection studies in the Southern Hemisphere and a global need for regional-scale TC track density projections. The independent TC detection and tracking algorithm utilised in this thesis is first evaluated to determine if it can simulate a realistic TC track climatology in reanalysis data. By way of cluster analysis, model-detected and observed TC tracks are compared and objective criteria for a consistent “TC track” definition are established. Regional-scale TC track projections are then examined in each TC basin around the globe. The exact methodology of cluster analysis in each basin is slightly modified to accommodate basin-scale differences in track climatology but generally follows a cluster assessment of TC tracks in observations, historical climate simulations and future climate projections using results from the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Regional impacts of the El Niño Southern Oscillation (ENSO) on TC tracks are also examined in current- and future-climates. Projection results are found to be supportive of existing studies, especially in the North Pacific and the Southern Hemisphere. Isolation of TC tracks into clusters indicated that the regional dominance of ENSO is well simulated by the CMIP5 models. Several regional changes in TC activity are noted and attributed to projected changes in the large-scale environment, and changes in ENSO-specific conditions.Doctor of Philosoph