WRF and SFIRE simulations of the Layman fuel reduction burn

Abstract

The Layman fire commenced as a routine fuel reduction burn in southwest Western Australia in October 2010. Late morning on the day following ignition, the fire was more active than fire management officers had expected under the prevailing conditions of wind, temperature and relative humidity in the local eucalypt forest fuels. A convective smoke plume developed over the fire, extending to a height of approximately 4000 m. Traditional measures for assessing fire behaviour gave no indication of the extent of the crown fire that occurred. This paper describes simulations of the fire using the coupled fire-atmosphere model WRF and SFIRE. The simulations show that fire-atmosphere feedback produces a northeast to northwest wind shift and surface convergence occur over the fire just after the fire’s buoyant plume grows through the overnight nocturnal layer into the residual mixed layer of the planetary boundary layer (PBL) from the previous day. The simulation results show that the timing of the wind shift and vertical growth of the fire plume closely matched the observed development of the convective smoke plume above the fire.