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

The Grass Fire Danger Index (GFDI) is a fire weather potential index that describes how current weather conditions and recent precipitation patterns could support a fire in grassy areas. GFDI calculations are based on McArthur, A.G. (1966, 1973) and dependent on air temperature, relative humidity, wind speed and grass curing. The metric was developed with the worst event considered corresponding to a value of 100. Here we provide predicted upper-bound GFDI values across the Australian landscape, defined for a set of Annual Exceedance Probabilities. We calculate GFDI 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. Grass curing values are derived from the 99th percentile of the values modelled from 2000 to 2019 by the Bureau of Meteorology MODIS MapVictoria grass curing dataset. 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. GFDI is used in operational contexts, including land use planning and Australian standards for building in bushfire prone areas, and it is a widely recognised fire weather metric. 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 Grass Fire Danger Index (GFDI) 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, near surface relative humidity and near surface wind speed.\nGrass Curing is calculated using the 99th percentile of the Bureau of Meteorology MODIS 8-day grass curing time series that are modelled from MODIS data using the method described in Wright et all (2015)[1]. The choice of percentile value used reflects the intention to capture “reasonable worst-case” conditions.\n\nThose inputs are combined using the equations developed by Noble et al (1980) [2] based on the work by McArthur (1966) [3] and McArthur (1973) [4]. GFDI is calculated for more than 43 years of hourly weather data, and then processed using extreme values analysis to model the expected GFDI values at annual exceedance probabilities.\n\n[1] Wright, D., Nichols, D., Slijepcevic, A., Kidnie, S., Chen, A., & Bessell, R. (2015). Improved assessment of grassland fuels in multiple jurisdictions across Australia. In Bushfire and Natural Hazards CRC & AFAC conference. Adelaide: Bushfire and Natural Hazards CRC.]\n[2] 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[3] McArthur, A.G., 1967. Fire behaviour in eucalypt forests: Forestry and Timber Bureau Leaflet 107. Forestry and Timber Bureau: Canberra, Australia.\n[4] McArthur, A.G. (1973) Grassland Fire Danger Meter Mark IV. Commonwealth Department of National Development Forestry and Timber Bureau, Canberra, ACT. (published as a circular slide rule). \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.