Size distribution of particles emitted from grass fires in the Northern Territory, Australia.

Abstract

This study investigated particle size distributions from the burning of several grass species, under controlled laboratory conditions, and also in the field, conducted during the dry season in the Northern Territory, Australia. The laboratory study simulated conditions such as burning phases and burning rate, and particle diameter differed depending on the burning conditions. Under fast burning conditions, smaller particles were produced with a diameter in the range of 30-60nm, whilst larger particles, with a diameter between 60-210nm, were produced during slow burning. The airborne field measurements of biomass particles found that under the boundary layer most of the early dry season (EDS) particles came from fresh smokes with a CMD of 83 ± 13nm, and most of the late dry season (LDS) particles came from aged smokes with a CMD of 127 ± 6nm. Vertical profiles of CMD showed that smaller particles were found higher within the atmosphere. These measurements provide insight into the scientific understanding of the properties of biomass burning particles in the Northern Territory, Australia.