An Assessment of Biomass Burning Emissions over Amazonia Using Airborne Measurements

Abstract

Biomass burning activities occur around the globe, throughout the year and are a huge source of atmospheric trace gases and particulate matter. Emissions of aerosol species from biomass burning include organic aerosol, inorganic aerosol and black carbon and the associated effects on weather, climate and human health are poorly understood and quantified. Aerosols have a direct effect on climate by reflecting and absorbing solar radiation, a semi-direct effect of increasing atmospheric stability and reducing convective cloud formation and an indirect effect by acting as cloud condensation nuclei (CCN). The emission of these species from biomass burning needs to be more fully understood in order for climate models to accurately represent and predict future emissions. The vast majority of biomass burning occurs in the tropics and this research presents data collected during the aircraft campaign of the South American Biomass Burning Analysis (SAMBBA), 2012. Biomass burning emissions from a smouldering rainforest fire and flaming cerrado fires were analysed and compared. Fire integrated emission ratios and emission factors for trace gas and particulate species for these two fire types were determined. Trace gas emissions differed substantially between the fire types and were highly dependent on the combustion efficiency of the fire, characterised by the integrated modified combustion efficiency (MCE) and are in agreement with previous studies values. Organic aerosol and black carbon emissions also differ between the fire types, with an order of magnitude more black carbon emitted from the flaming cerrado fires and more than double the amount of organic aerosol per kg fuel burnt emitted from the smouldering rainforest fire. Particulate phase species emitted from both fire types sampled are generally within the range or lower than those reported in previous studies. A possible cause of the lower black carbon emissions compared to literature is due to the different measurement techniques used. Organic aerosol emission was found to be dependent on combustion efficiency, but for black carbon there is no significant dependence. Inorganic aerosols vary between fire types and are more dependent on fuel type and composition. The smouldering rainforest fire sampled was likely initiated due to lightning but results indicated that this fire is representative of smouldering deforestation fires. Recent studies show a shift from deforestation to cerrado fires in Brazil, which could lead to significant increases in CO2 and BC concentrations in the region and have effects on future climate. The results presented in this dissertation provide up to date trace gas and particulate emission ratios and emission factors for fire type specific biomass burning in Brazil which are significant in terms of future climate change and can be used to challenge atmospheric weather and climate models.

Date of Award	1 Jan 1824
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Hugh Coe (Supervisor)