Modelling tropical cyclone wave population of the Great Barrier Reef

Abstract

Wave information is generated for the population of tropical cyclones that affects the Great Barrier Reef region. Several models are combined to create a wave database at 150,000 locations at a resolution of 1,500 m throughout this large and remote region. An autoregressive time series model, based on historical data, generated time series of position and central pressure for a very large ensemble of synthetic tropical cyclones. An empirical model was used to create the wind field throughout the wave generating area. The wind field had three components: The primary cyclone vortex, a secondary vortex used to model the low-pressure trough in which a cyclone is often embedded, and the external synoptic scale wind field created between the cyclone and the mid latitude high-pressure systems. WAMGBR, a wave generation model especially adapted for conditions in the Great Barrier Reef, was used to simulate a very large ensemble of storms on a nested grid system in transformed spherical coordinates. The results of the study are significant wave heights, peak periods, and mean directions for return periods between 20 and 1,000 years.