The national Tropical Cyclone Hazard Assessment (TCHA) defines the severe wind hazard posed to Australia based on the frequency and intensity of tropical cyclones making landfall around the Australian coastline. Contact us at hazards@ga.gov.au if you need further information. URL: https://www.ga.gov.au/about/projects/safety/tcha <b>Value: </b>The TCHA provides vital information to emergency managers, town planners and infrastructure owners to plan and reduce the threat of tropical cyclone hazard on the Australian coast, and for the insurance industry to understand the tropical cyclone risk as an input to pricing insurance premiums. The TCHA is a key data source to calculate local cyclone impact models for the development of evidence-based disaster management plans, evacuation plans or inform infrastructure planning or mitigation strategies. High risk areas can be identified and prioritised for further analysis, or to extract scenarios to explore risk mitigation and community safety at a local and regional level. The TCHA includes a catalogue of synthetic tropical cyclone events (including tracks and wind fields), hazard profiles for selected locations across Australia, and maps of annual recurrence interval (ARI) wind speeds due to tropical cyclones. Geoscience Australia provides essential evidence based information to government and emergency managers around Australia to improve our communities' ability to prepare for, mitigate against and respond to natural disasters. <b>Scope: </b>Continental scale.

The 2018 Tropical Cyclone Hazard Assessment (TCHA18) provides an evaluation of the likelihood and intensity (“how big and how often”) of the occurrence of tropical cyclone winds across the Australian region, covering mainland Australia, islands and adjacent waters. It is a probabilistic evaluation of the expected maximum gust wind speeds with a range of annual exceedance probabilities (or conversely, average recurrence intervals). The assessment is derived using a statistical-parametric model developed by Geoscience Australia called the Tropical Cyclone Risk Model (TCRM). Maximum 0.2-second duration, 10-metre above ground wind speeds are calculated for Standard Australia's AS/NZS 1170.2 (2011) terrain category 2 (0.02 m roughness length) surface conditions, over a 0.02 degree grid across Australia. Maps of average recurrence interval (ARI) wind speeds of 100- and 500-year ARI are provided in a separate product suite.

Geoscience Australia has produced a National Tropical Cyclone Hazard Assessment (TCHA18). The 1%/0.2% Annual Exceedance Probability Maps provides 0.2-second duration, 10-metre above ground level gust wind speeds across Australia arising from tropical cyclone events over a 2-km grid, for 1% and 0.2% annual exceedance probability (100- and 500-year annual recurrence interval respectively). Surface conditions are assumed to correspond to terrain category 2 conditions as defined in AS/NZS 1170.2 (2011).

The TCHA18 Data collection covers the model output generated by the Tropical Cyclone Risk Model as part of the assessment. This includes average recurrence interval wind speeds, stochastic track catalogues, wind fields and intermediary data. It also includes an evaluation track catalogue, used to evaluate the performance of the model with respect to historical landfall rates, frequency and track density.

The TCHA18 Stochastic Event Catalogue contains artificially generated tropical cyclone tracks and wind fields representing 10000 years of tropical cyclone activity. The catalogue stores the track of each event in annual collections (i.e. one simulated year per file). The wind field of each event is stored in a separate file, containing the maximum wind speed, the components (eastward and northward wind) corresponding to the maximum wind speed, and the minimum sea level pressure from the event. All events are recorded in a relational database file, which contains records of the distance of closest passage, maximum wind speeds and the direction of the maximum wind speed for over 400 locations in Australia. The database also contains records of the average recurrence interval wind speeds at those stations. The database is intended to simplify the process of identifying individual events in the catalogue for more detailed modelling to support scenario planning for emergency management, for example.

The TCRM Stochastic Event Catalogue contains artificially generated tropical cyclone tracks and wind fields representing 10000 years of tropical cyclone activity. The catalogue is stored by year, with a track file and wind field file. The wind field file contains the maximum wind speed from all events occuring in the corresponding track file (i.e. it represents annual maximum wind speeds).