Comparisons of Future Changes in Oceanic Tropical Cyclones

The short historical record of tropical cyclones (TCs) combined with the rarity of occurrences in any given location makes it challenging to evaluate past TC impacts and predict future changes. Analysis of Australian cyclones is limited by both the short observational record and the fact that several changes have occurred in observing practices. Despite the short record, significant changes have already been observed. The number of strong TCs has increased, the latitude of storm lifetime peak intensity has migrated southward, and TC rainfall totals and intensities have increased. If this southward shift continues, cities in marginal regions could experience TCs more often than in the past, with extratropical transitioning storms also extending their impacts to higher latitudes. Statistical modeling gets around the rarity of occurrence. Still, these models are commonly based on past storm tracks and, therefore, largely ignore recent and near-term future changes in storm tracks.

The NCAR CESM Decadal Prediction Large Ensemble Project (DPLE) and Large Ensemble (LENS) datasets are alternative ways to explore how TC activity has changed in the recent climate and how they are predicted to change in the future. In this study, we investigate how TC characteristics have changed in recent decades and are expected to change along the Australian coastlines as well as in the New Zealand area. We will compare the three regions – East and West Coast of Australia and New Zealand – to better understand the differences and similarities in these regions. This study specifically examines the storm intensity, precipitation rates/storm rainfall total, and impacts on coastal and inland communities.