Regional Influence of Aerosol Emissions from Wildfires
New metric developed for describing aerosol properties of wildfires and simulating their impact on climate and air quality.
Researchers found a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and climate over the Pacific Northwest. Using real-time measurements from a fixed ground site, researchers found that the enhancement ratios (ERs) describing regional biomass burning organic aerosol concentrations, as well as their chemical compositions, were influenced by a mass combustion efficiency (MCE) at the time of emission impacting the aerosol’s oxidation state.
Wildfires are a large and variable component of biomass burning emissions, such as agricultural and residential wood burning, that influence Earth’s climate. They contribute to atmospheric aerosol concentrations and affect regional air quality, global climate, and human health. Better understanding of the components, properties, and impacts of wildfire emissions are needed to include them in global climate models and may provide insights for mitigating their climate and air quality impacts.
In this study, researchers at the Department of Energy’s Pacific Northwest National Laboratory and collaborators studied the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States. They used real-time measurements from a fixed ground site and an instrument-loaded aircraft in Central Oregon at the Mount Bachelor Observatory. They found that the regional characteristics of biomass burning aerosols depended strongly on the modified combustion efficiency (MCE), an index of a fire’s combustion processes. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (∼1 h old) and emissions sampled after atmospheric transport (6-45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.
Pacific Northwest National Laboratory
The work was funded by the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research as part of the Atmospheric Radiation Measurement (ARM) and Atmospheric System Research programs. They used data from the ARM Climate Research Facility, a DOE Office of Science user facility. Other researchers were funded by the National Science Foundation.
Collier, S., S. Zhou, T. B. Onasch, D. A. Jaffe, L. Kleinman, A. J. Sedlacek, III, N. L. Briggs, J. Hee, E. Fortner, J. E. Shilling, D. Worsnop, R. J. Yokelson, C. Parworth, X. Ge, J. Xu, Z. Butterfield, D. Chand, M. K. Dubey, M. S. Pekour, S. Springston, and Q. Zhang. 2016. “Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign,” Environmental Science and Technology 50(16), 8613-22. DOI: 10.1021/acs.est.6b01617.