Applications of Very High Resolution Atmospheric Modelling for Bushfires

This is a paper presented at the 2013 Bushfire CRC Research Forum.

Bushfire behaviour is well known to be sensitive to the weather. What is less well appreciated is that the behaviour is affected by all scales of atmospheric behaviour, from the large-scale and long-term (drought), through the medium-scale (weather systems such as fronts and wind changes) to the small-scale (short-term fluctuations in humidity and wind strength and direction). Ongoing improvements in numerical weather prediction (NWP) have given us the ability to resolve features as small as a few hundred metres, and provide an unprecedented window into atmospheric structures that may affect a bushfire. Here, we summarise the past two years of research by our group into fine-scale modelling of severe fire weather. In that time, we have modelled and verified the meteorology of events including Black Saturday of 2009, the Eyre Peninsula fire of 2005, the Margaret River fires of 2011, the Blue Mountains fires of 2001, and the Dunalley fire of 2013. We have identified several medium to small-scale meteorological phenomena that have the potential to significantly escalate a fire, and in the case of the Margaret River fire have good evidence that the small-scale meteorology was the major contributor to the fire intensity and spread at a critical point in its history. We will summarise some of these phenomena, and indicate the prospects for predicting them in the future, thereby improving firefighter effectiveness and safety. However, while our focus is on meteorology, we note that other factors, including fuels and topography, also strongly influence fire behaviour.

This paper is an interim review and summary of our research, and aims for breadth at the expense of depth. Readers interested in more detail should refer to the more detailed reports cited herein. This research forms one section of the Fire Impact and Risk Evaluation Decision Support Tool (FireDST) project, and has been funded by the Bushfire CRC and the Australian Bureau of Meteorology. The results of our meteorological modelling have also been a key input into fire modelling, smoke dispersion and risk-assessment research under that project.