NBIC-ACS Stage 2 Forest Fire Danger Index - baseline scenario, 5%, 2% and 1% annual exceedance probabilities

The McArthur Forest Fire Danger Index (FFDI) is a fire weather potential index that describes how current weather conditions and recent precipitation patterns could support a fire in forested areas. FFDI calculations are based on McArthur, A.G. (1967) and dependent on air temperature, relative humidity, wind speed. The metric was developed with the worst bushfire event at the time – Victoria 1939 – corresponding to a value of 100. Here we provide predicted upper-bound FFDI values across the Australian landscape, defined for a set of Annual Exceedance Probabilities. We calculate FFDI based on the latest Bureau of Meteorology historical weather reanalysis BARRA-R2, reporting modelled hourly weather conditions from 1979 to current at a spatial resolution of approximately 11 kilometres. More than 400,000 data points at every location are then processed using the National Bushfire Intelligence Capability (NBIC) Extreme Values Analysis to predict extreme daily maximums and their likelihood. FFDI was historically used to define bushfire hazard, including the official Fire Danger Rating issued by operational agencies. While its use in this context is no longer recommended, FFDI remains a widely recognised fire weather metric that is commonly understood and informs jurisdictional policies and building standards. All these characteristics result in datasets that are a significant advancement in defining extreme fire weather, surpassing previous approaches and offering a robust foundation for informed decision-making in managing and mitigating Australia’s growing bushfire risks in a changing climate.\nLineage: The McArthur Forest Fire Danger Index (FFDI) data - baseline scenario is calculated using the historical weather reanalysis BARRA-R2 by Bureau of Meteorology (https://dx.doi.org/10.25914/90rq-d839). Variables used are near surface air temperature, precipitation, near surface relative humidity and near surface wind speed.\nThose inputs are combined using the equations developed by Noble et al (1980) [1] based on the work by McArthur (1967) [2]. McArthur Drought Factor is calculated using the modified formulation published in Finkele et al (2006) [3].\n\nFFDI is calculated for more than 43 years of hourly weather data, and then processed using extreme values analysis to model the expected FFDI values at annual exceedance probabilities.\n\n[1] Noble, I.R., Gill, A.M. and Bary, G.A.V., 1980. McArthur's fire‐danger meters expressed as equations. Australian journal of ecology, 5(2), pp.201-203. https://doi.org/10.1111/j.1442-9993.1980.tb01243.x\n[2] McArthur, A.G., 1967. Fire behaviour in eucalypt forests: Forestry and Timber Bureau Leaflet 107. Forestry and Timber Bureau: Canberra, Australia.\n[3] Finkele, K., Mills, G.A., Beard, G. and Jones, D.A., 2006. National gridded drought factors and comparison of two soil moisture deficit formulations used in prediction of Forest Fire Danger Index in Australia. Australian Meteorological Magazine, 55(3), pp.183-197.\n\nImportant Disclaimer:\nCSIRO advises that the information contained in this dataset comprises general statements and information based on scientific research. The user is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it.