Satellite-based comparison of fire intensity and smoke plumes from prescribed fires and wildfires in south-eastern Australia

Abstract

Smoke pollution from wildfires can adversely affect human health, and there is uncertainty about the amount of smoke pollution caused by prescribed v. wildfires, a problem demanding a landscape perspective given that air quality monitoring is sparse outside of urban airsheds. The primary objective was to assess differences in fire intensity and smoke plume area between prescribed fires and wildfires around Melbourne and Sydney, Australia. We matched thermal anomaly satellite data to databases of fires in forests surrounding both cities. For each matched fire we determined hotspot count and quantified their intensity using the fire radiative power (FRP) measurement. Smoke plumes were mapped using MODIS true colour images. Wildfires had more extreme fire intensity values than did prescribed burns and the mean size of wildfire plumes was six times greater than of prescribed fire plumes for both cities. Statistical modelling showed that the horizontal area covered by smoke plumes could be predicted by hotspot count and sum of FRP, with differences between cities and fire type. Smoke plumes from both fire types reached both urban areas, and particulate pollution was higher on days affected by smoke plumes. Our results suggested that prescribed fires produced smaller smoke plume areas than did wildfires in two different flammable landscapes. Smoke plume and FRP data, combined with air pollution data from static monitors, can be used to improve smoke management for human health.