FIREX Science Questions

The following list of specific science questions can be addressed using a combination of the large-scale NOAA WP-3D field campaign and the smaller-scale field and laboratory experiments.

  1. What are the emissions of gases, aerosols, aerosol precursors and greenhouse gases from North American fires?
    • How well do inventories represent BB emissions?
    • How do the relative amounts of smoldering and flaming impact smoke chemistry and injection altitude?
    • What is the composition and volatility of the previously unidentified fraction of the emissions?
    • What are the emissions of greenhouse gases methane and N2O?
    • What are the emissions of air toxics?
    • Can we relate emissions to weather? For example, do fires emit more trace gases and aerosols and relatively more or less black carbon in low humidity conditions?

    Approach: After development in the laboratory, new instruments will be used in the fire science laboratory to identify previously unidentified compounds and understand their importance. Emission factors determined in the lab will be compared to near-field measurements during the preparatory and intensive field studies using the mobile laboratory for smoldering and the NOAA WP-3D and Twin Otter aircraft for flaming plus smoldering emissions.

  2. What is the chemical transformation of those emissions?
    • What are the formation mechanisms for secondary species (ozone, SOA and sulfate) and what environmental or chemical conditions control their relative importance?
    • How does the chemical transformation change with meteorological conditions?
    • How do nighttime chemical transformations involving NO3, N3O5 and O3 influence the composition and evolution of smoke plumes?
    • How important is nighttime chemistry for production of secondary organic aeorosl and brown carbon aerosol in smoke?
    • What are the mechanisms that lead to PAN formation in fire plumes during daytime and nighttime?
    • What is the diurnal cycle of free radical and oxidant production in fire plumes, and how important are reactions with different oxidants at various times of day?
    • How important is the formation of organic aerosol from aqueous-phase processes?

    Approach: Fire emissions will be aged in the CIRES atmospheric simulation chamber with specific focus on the identified SVOCs and VOCs. The NOAA WP-3 aircraft will be used to track the chemical evolution in the field.

  3. What is the local air quality and visibility impact of North American fires?
    • How does local meteorology impact fire evolution?
    • How well do local models predict the BB impact on air quality and visibility?
    • How important is nighttime smoke for populated areas and what are the health impacts?

    Approach: The NOAA WP-3D aircraft will be used to map out the extent of the fire plume and the mobile laboratory will be used in populated areas to measure concentrations of fire emissions. The results will be compared to local and regional models, and ground and mobile–lab observations will be used to assess population exposures to fires.

  4. What are the regional and long-term impacts of North American fires?
    • How strongly are the composition and distribution of pollutants over North America influenced by BB?
    • How far afield can BB emissions from common, but smaller fires impact air quality?
    • What are the future changes in BB impacts as a result of climate change and changes to fire management practices?

    Approach: The Storm Peak station is often influenced by long-range transport of BB emission. We will determine the air pollutant contribution from fire emissions during the burning season. With the NOAA WP-3D we will probe aged smoke plumes within the reach of the aircraft throughout North America.

  5. What are the climate-relevant properties of BB aerosols?
    • What are the extinction, absorption and CCN properties of BB aerosol as a function of smoke age on hours to days time scale?
    • What role does brown carbon and coatings on black carbon particles play in the optical properties of smoke?
    • How should BB aerosols be assessed via remote (i.e. satellite) observations?
    • What fraction of the organic aerosol is primary versus secondary at various time scales?
    • How well do regional and global models predict the BB influence on climate?

    Approach: Aerosol extinction, absorption and cloud nucleating properties will be measured from the aircraft for different fire types. Correlating the variability in aerosol with inert tracers of BB such as acetonitrile will describe the fraction of aerosol that is primary versus secondary.