Evaluation of the Tropical Cyclone Risk Model at Geoscience Australia Using AWS Observations

Severe wind from tropical cyclones (TC) can cause significant damage to property and infrastructure, and accurately predicting these impacts is essential for ensuring community safety. At Geoscience Australia (GA), the Tropical Cyclone Risk Model (TCRM) is a statistical-parametric tool designed to estimate the severe wind hazards posed by TCs.

To assess the performance of TCRM, all TCs impacting Australia from 1998 to 2023 were simulated using various wind profile settings. Since TCRM currently lacks adjustments for local landscape effects on wind speed (e.g., topographic enhancements or variations due to vegetation or built environments), GA’s wind multiplier was applied to convert TCRM’s regional wind to local wind for each TC. Additionally, a new multiplier, derived from the Parallelized Large-Eddy Simulation Model (PALM), was used to calculate local wind. The local winds from these two multipliers were then compared and validated against 1-minute Automatic Weather Station (AWS) observations from the Bureau of Meteorology (BoM).

The results indicate that the Willoughby wind profile outperforms other wind profiles, with a mean sea level pressure error of just 0.2 hPa compared to AWS observations over the mainland. Although the local wind from both multipliers aligns closely across 82 AWS stations (a mean peak wind gust error of -1 m/s for the GA multiplier and 0.2 m/s for the new multiplier), significant discrepancies may occur in regions with steep mountain ranges, urban areas with high-rise buildings, and other areas with complex topography.