Formaldehyde and nitrogen dioxide in smoke plumes from Australia's Black Saturday fires

The ‘Black Saturday’ fires were a series of devastating bushfires that burned across Victoria, Australia, during February 2009. The smoke plume from Saturday the 7th February, the worst day of the fires, separated from subsequent emissions and persisted for several weeks, providing the opportunity to track the changing composition of the smoke plume as it aged. In this study we have used satellite data from the Ozone Monitoring Instrument (OMI) and the Atmospheric InfraRed Sounder (AIRS) to characterise the emissions of formaldehyde and nitrogen dioxide from the fires. Emission ratios with respect to carbon monoxide are determined for formaldehyde (0.017 ± 0.004 mol.mol-1) and nitrogen dioxide (0.004 ± 0.001 mol.mol-1). Additionally OMI UV Aerosol Index is used to track the smoke plume and infer how the concentration of these gases changes as the smoke ages. Our study suggests that formaldehyde concentrations within the smoke plume increase during the first day before declining to background levels within 2 days after emission. Nitrogen dioxide concentrations show a monotonic decrease reaching background levels about 1 day after emission.