Near-field emission profiling of tropical forest and Cerrado fires in Brazil during SAMBBA 2012

• Published in: Atmospheric chemistry and physics Vol. 18; no. 8; pp. 5619 - 5638
• Main Authors: Hodgson, Amy K., Morgan, William T., O'Shea, Sebastian, Bauguitte, Stéphane, Allan, James D., Darbyshire, Eoghan, Flynn, Michael J., Liu, Dantong, Lee, James, Johnson, Ben, Haywood, Jim M., Longo, Karla M., Artaxo, Paulo E., Coe, Hugh
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 24-04-2018; Copernicus Publications
• Subjects: Aerosol concentrations; Aerosols; Airborne sensing; Biomass; Biomass burning; Black carbon; Burning; Climate models; Combustion; Combustion efficiency; Components; Earth; Emission analysis; Emission inventories; Emission measurements; Field emission; Fires; Forest & brush fires; Forest fires; Fuel combustion; Fuel mixtures; Mass spectrometry; Measurement techniques; Modelling; Organic chemistry; Particulate emissions; Photometers; Plumes; Rainforests; Ratios; River basins; Satellites; Scaling; Smoke; Smoke plumes; Smoldering; Soot; Trace gases; Tropical climate; Tropical forests; Wildfires; Brazil; Cerrado Biome
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-18-5619-2018

We profile trace gas and particulate emissions from near-field airborne
measurements of discrete smoke plumes in Brazil during the 2012 biomass
burning season. The South American Biomass Burning Analysis (SAMBBA) Project
conducted during September and October 2012 sampled across two distinct fire
regimes prevalent in the Amazon Basin. Combined measurements from a Compact
Time-of-Flight Aerosol Mass Spectrometer (C-ToF-AMS) and a Single Particle
Soot Photometer (SP2) are reported for the first time in a tropical biomass
burning environment. Emissions from a mostly smouldering tropical forest
wildfire in Rondônia state and numerous smaller flaming Cerrado fires
in Tocantins state are presented. While the Cerrado fires appear to be
representative of typical fire conditions in the existing literature, the
tropical forest wildfire likely represents a more extreme example of biomass
burning with a bias towards mostly smouldering emissions. We determined fire-integrated
modified combustion efficiencies, emission ratios and emission
factors for trace gas and particulate components for these two fire types,
alongside aerosol microphysical properties. Seven times more black carbon was
emitted from the Cerrado fires per unit of fuel combustion (EFBC
of 0.13 ± 0.04 g kg−1) compared to the tropical forest
fire (EFBC of 0.019 ± 0.006 g kg−1), and more
than 6 times the amount of organic aerosol was emitted from the tropical
forest fire per unit of fuel combustion (EFOM of
8.00 ± 2.53 g kg−1, EFOC of
5.00 ± 1.58 g kg−1) compared to the Cerrado fires
(EFOM of 1.31 ± 0.42 g kg−1, EFOC
of 0.82 ± 0.26 g kg−1). Particulate-phase species emitted from the fires sampled are generally lower
than those reported in previous studies and in emission inventories, which is
likely a combination of differences in fire combustion efficiency and fuel
mixture, along with different measurement techniques. Previous modelling
studies focussed on the biomass burning season in tropical South America have
required significant scaling up of emissions to reproduce in situ and
satellite aerosol concentrations over the region. Our results do not indicate
that emission factors used in inventories are biased low, which could be one
potential cause of the reported underestimates in modelling studies. This
study supplements and updates trace gas and particulate emission factors for
fire-type-specific biomass burning in Brazil for use in weather and climate
models. The study illustrates that initial fire conditions can result in
substantial differences in terms of their emitted chemical components, which
can potentially perturb the Earth system.