Quantification of Gas and Aerosol Characteristics from North American Fires: Emissions, Evolution and Exposure

Open biomass burning (BB) fires in North America, including wildland fires and agricultural burning, have a significant impact on our nation’s air quality, our citizen’s health, and our overall contribution to global climate forcing. Emission, evolution, and transport of gas-phase species, aerosol, and radical precursors from open fires, with a focus on greenhouse gases, absorbing aerosol (black and brown carbon), and health-related compounds (i.e., EPA criteria pollutants including particulate matter, PM), must be understood in order to project the climate and health impacts of policy decisions about wildfire and land use management onto the relevant local, regional and global scales. Specific outstanding issues include a quantitative radical-based characterization of the photochemistry in BB plumes and its impact on O₃ formation and aerosol processing, the impact of nighttime BB emissions and transformations on nighttime air quality and exposure, source (i.e., fuel and combustion conditions) attribution of transported aerosol, and connections between weather and spatial extent of impact.

We propose to deploy the Aerodyne Mobile Laboratory (AML) as part of the NOAA AC4 Program FIREX project to address several knowledge gaps related to the impact of BB on air quality and climate. The AML will participate in two planned studies at the USFS Fire Sciences Laboratory and will be deployed over a wide geographical range to sample BB plumes as part of the field intensive portion of the FIREX project in direct coordination with other ground and aircraft sampling platforms (e.g., the NOAA P3). The AML platform provides a range of sampling strategies, such as rapid deployment to new fires for emissions characterization, fixed site sampling in downwind locations for studying atmospheric evolution of the plumes, stationary sampling as an expanded laboratory space for USFS Fire Sciences Laboratory experiments, and mapping of plume�?�affected urban areas for health�?�related exposure.

We will deploy multiple new measurement techniques during FIREX onboard the AML, including a chemical amplification technique for measuring peroxy radicals (HO₂+RO₂), a thermal-dissociation technique for measuring organic nitrates, a negative iodide chemical ionization mass spectrometer (I- CIMS) equipped with Filter Inlet for Gases and AEROsols collector module (FIGAERO) for measuring gas and particle phase compounds, a soot particle aerosol mass spectrometer (SP-AMS) for characterizing the chemical composition of BrC and BC particles (potentially including nitrogen compounds), and several cavity attenuated phase spectroscopy (CAPS)-based single scatter albedo (SSA) monitors for tracking aerosol optical properties (scattering and extinction). We will leverage the mobile capabilities of the AML platform and our state-of-the-art instrumentation suite to focus on four primary objectives: (1) characterize the radical chemistry that contributes to O₃ and SOA formation and daytime evolution of the BB plume; (2) track the chemical evolution and spatial extent of nocturnal BB plumes; (3) identify source specific gas- and particle-phase chemical markers in BB plumes; and (4) characterize the initial and evolving chemical, physical, and optical properties of BB aerosol, including BC and BrC particles. These four goals are closely aligned with the goals of the NOAA FIREX project and with NOAA’s long-term climate goal of improved scientific understanding of the changing climate system and its impacts. The matrix of measurements and sampling strategies will provide a rich and unique data set for regional and global climate models and epidemiological models, thus benefiting the general public and scientific community.