Research has revealed that the extremely hot, dry and windy conditions on Black Saturday combined with structures in the atmosphere called 'horizontal convective rolls' -similar to streamers of wind flowing through the air - which likely affected fire behaviour.
The study is the first of its kind to produce such detailed, high-resolution simulations of weather patterns on the day and provides insights for future fire management and warning systems.
The work was led by Dr Todd Lane and Ms Chermelle Engel from The University of Melbourne with Prof Michael Reeder (Monash University) and Dr Michael Rezny (ARC Centre of Excellence for Climate System Science).
The team examined meteorological conditions across Victoria on 7 February, 2009. The analysis used a very high-resolution weather forecasting model, which represented the airflow over the entire state on 400 metre weather grids, which are about ten times smaller than the grids used in operational weather forecasting. Weather conditions observed on the day were used to validate the model.
"Fire fighters reported extraordinary behaviour from the Black Saturday bushfires. We wanted to understand what weather characteristics produce these extreme conditions to aid future fire control efforts," said Dr Lane from the School of Earth Sciences at The University of Melbourne.
"We found that weather events at a horizontal scale of about 10 kilometres introduced variability in the wind, temperature and humidity conditions. These smaller events combined to produce significant variability in fire danger across much of Victoria."
"Similar wind patterns have been observed previously on hot days, but the convective rolls on Black Saturday were unusual as the high temperatures meant they were stronger and spaced wider apart. The rolls create bands of fast and slow wind around 5-10 kilometres apart, causing variations in fire danger. Fire spread is related to wind spee
|Contact: Nerissa Hannink|
University of Melbourne