Impact of the 2016 Southeastern US Wildfires on the Vertical Distribution of Ozone and Aerosol at Huntsville, Alabama

Abstract

We present an integrated analysis of measurements from ozonesonde, ozone (O3) Differential Absorption Lidar (DIAL), ceilometer, surface monitors, and space‐borne observations in conjunction with the regional chemical transport model Weather Research and Forecast Model with Chemistry (WRF‐Chem) to investigate the effect of biomass burning emissions on the vertical distribution of ozone and aerosols during an episode of the 2016 Southeastern United States wildfires. The ceilometer and DIAL measurements capture the vertical extent of the smoke plumes affecting the surface and upper air over Huntsville, AL. The model evaluation results suggest a scaling factor of 3–4 for the wildfire aerosol emissions in order to better match observed aerosol optical depth, fine particulate matter (PM2.5), and DIAL aerosol extinction. We use the scaled emissions together with WRF‐Chem tendency diagnostics to quantify the fire impacts and characterize the processes affecting the vertical ozone budget downstream of the wildfires. During the daytime at Huntsville on November 12 and 13, we estimate that fire emissions contribute 12–32 μg/m3 (44%–70%) to hourly surface PM2.5 and 7–8 ppb/10 h (30%–37%) to the surface ozone increase (ΔO3), respectively. Net chemical ozone production (PO3) is the main contributor to upper‐air ozone, which reaches 17–19 ppb/10 h with an estimated 14%–25% contribution from fire sources. Vertical mixing and advection are the major drivers of changes in surface ozone. Model analysis indicates that advection dominates ΔO3 due to fire emissions below 1 km on November 12, while local photochemistry dominates on November 13. These results quantify the different mechanisms through which fires can influence the vertical ozone budget and point out uncertainties in fire inventories that need to be addressed in light of the increasing role of wildfires on air quality.

Were Wildfires Responsible for the Unusually High Surface Ozone in Colorado During 2021?

“…Wildfire smoke and pyrogenic O 3 can be transported hundreds or even thousands of km in the free troposphere before being entrained into the boundary layer far downwind (Johnson et al., 2021; Lin et al., 2021; McKeen et al., 2002). In‐situ measurements of pyrogenic O 3 in the free troposphere have rarely been made outside of aircraft‐based field campaigns, but O 3 ‐rich smoke plumes have also been detected by ground‐based lidars belonging to the NASA‐sponsored Tropospheric Ozone Lidar Network (TOLNet) (Dreessen et al., 2016; Kuang et al., 2017; Langford et al., 2020, Johnson et al., 2021; Wang et al., 2021) and the relationship between the aerosol backscatter ( β ) and O 3 in the smoke can be used to estimate the amount of pyrogenic O 3 above the lidar (Langford et al., 2020). Here we use the measurements from the Tunable Optical Profiler for Aerosol and oZone (TOPAZ) lidar (Alvarez et al., 2011; Langford et al., 2019), located at the NOAA David Skaggs Research Center (DSRC) to characterize the smoke and O 3 distributions above Boulder.…”

Mobile Observations of Ozone and Aerosols in Alabama: Southeastern US Summer Pollution and Coastal Variability

“…Fire smoke is another important contributor to regional air pollution due to its substantial emissions of particulate matter (PM) and O 3 precursors such as CO and NOx (Jaffe & Wigder, 2012; Johnson et al., 2016, 2021) and often results in surface O 3 exceedance (Dreessen et al., 2016). The O 3 production inside a smoke plume highly varies with its lifetime (Wang et al., 2021). Agricultural fires in the SEUS generate CO emissions equal to about 9% of mobile sources annually (Liu et al., 2016).…”