Changes in ozone and precursors during two aged wildfire smoke events in the Colorado Front Range in summer 2015

Abstract

Abstract. The relative importance of wildfire smoke for air quality over the western US is expected to increase as the climate warms and anthropogenic emissions decline. We report on in situ measurements of ozone (O 3 ), a suite of volatile organic compounds (VOCs), and reactive oxidized nitrogen species collected during summer 2015 at the Boulder Atmospheric Observatory (BAO) in Erie, CO. Aged wildfire smoke impacted BAO during two distinct time periods during summer 2015: 6-10 July and 16-30 August. The smoke was transported from the Pacific Northwest and Canada across much of the continental US. Carbon monoxide and particulate matter increased during the smoke-impacted periods, along with peroxyacyl nitrates and several VOCs that have atmospheric lifetimes longer than the transport timescale of the smoke. During the August smokeimpacted period, nitrogen dioxide was also elevated during the morning and evening compared to the smoke-free periods. There were nine empirically defined high-O 3 days during our study period at BAO, and two of these days were smoke impacted. We examined the relationship between O 3 and temperature at BAO and found that for a given temperature, O 3 mixing ratios were greater (∼ 10 ppbv) during the smoke-impacted periods. Enhancements in O 3 during the August smoke-impacted period were also observed at two long-term monitoring sites in Colorado: Rocky Mountain National Park and the Arapahoe National Wildlife Refuge near Walden, CO. Our data provide a new case study of how aged wildfire smoke can influence atmospheric composition at an urban site, and how smoke can contribute to increased O 3 abundances across an urban-rural gradient.

In situ measurements of trace gases, PM, and aerosol optical properties during the 2017 NW US wildfire smoke event

“…3906 V. Selimovic et al: Regional wildfire smoke: trace gases, PM, and aerosol optical properties fraction of the global BB in the western US is responsible for a significant portion of US air quality impacts (Park et al, 2007;Liu et al, 2017;Wilkins et al, 2018;Zhou et al, 2018) and contributes to increasing health concerns. Wildfire smoke has been shown to have adverse respiratory and cardiovascular health effects, is associated with mortality and morbidity, and exhibits lung toxicity and mutagenicity (Le et al, 2014;Liu et al, 2015;Reid et al, 2016;Adetona et al, 2016;Kim et al, 2018). In some cases, long-range transport of biomass burning emissions can cause air quality standards to be exceeded hundreds or thousands of kilometers downwind of the fire source (Jaffe et al, 2013;.…”

Seasonality, sources and sinks of C1–C5 alkyl nitrates in the Colorado Front Range

“…Because this event fails to meet the model assumptions, the subsequent calculation results in a decreasing photochemical age through the day. These examples from late August 2015 coincide with smoke intrusion into the Front Range from wildfires in the Washington and Idaho (Lindaas et al, 2017) -although we note that most other summer 2015 days designated as smoke-impacted do not show this anomalous 2-PrONO 2 /propane trend.…”

The IAGOS NO<sub>x</sub> Instrument – Design, Operation and First Results from Deployment aboard Passenger Aircraft

“…S3). These fire emissions contributed also largely to poor air quality in the mid-US at that time 15 (Creamean et al, 2016;Lindaas et al, 2017). Further analyses are beyond the scope of this paper, whereas this showcase study already indicates the possibilities for air quality studies using the full amount of IAGOS observations.…”