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The Relationship between Aerosol Optical Properties and Gases at the Table Mountain Monitoring Station during the 2020 Colorado Wildfire Season

L. Schmeisser1,2, B. Andrews1,2, P.J. Sheridan2, G. Petron1,2 and J. Kofler1,2

1Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309; 3039471589, E-mail: Lauren.schmeisser@noaa.gov
2NOAA Global Monitoring Laboratory (GML), Boulder, CO 80305

The summer and fall of 2020 brought the most extreme wildfire year Colorado has ever experienced. The number of wildfires and area burned exceeded records from all previous years. Continuous in-situ surface measurements of several aerosol optical properties and three combustion trace gas markers (carbon monoxide [CO], methane [CH4], and carbon dioxide [CO2]) at the Table Mountain facility north of Boulder offer insight into the influence of these wildfires on downstream air quality. The aerosol properties and trace gas concentrations are well above climatological levels at the site during times when the station is influenced by wildfire smoke. We combine back trajectories with an analysis of aerosol optical properties, including scattering coefficient, absorption coefficient, scattering and absorption Ångström exponents and single scattering albedo, to relate smoke source to in-situ observations. We further analyze the relationships between aerosol properties and CO mixing ratios to determine whether these relationships enable us to categorize smoke plume characteristics. The results further our understanding of the variety of smoke events (e.g., long-range transport, fresh from local plumes, etc.) that influenced Colorado’s Front Range air quality and the associated aerosol and gas signatures during the 2020 wildfire season. Furthermore, the results show a need for more targeted aerosol and gas measurements during smoke events, thus providing strong motivation for the planned Global Monitoring Laboratory mobile facility to be deployed in summer 2022.

Figure 1

Figure 1. Relationship between aerosol absorption coefficient and CO concentration colored by absorption Angstrom exponent.