Quantifying the contribution of thermally driven recirculation to a high‐ozone event along the Colorado Front Range using lidar. Issue 17 (15th September 2016)

• Record Type: Journal Article
• Authors: Sullivan, John T.; McGee, Thomas J.; Langford, Andrew O.; Alvarez, Raul J.; Senff, Christoph J.; Reddy, Patrick J.; Thompson, Anne M.; Twigg, Laurence W.; Sumnicht, Grant K.; Lee, Pius; Weinheimer, Andrew; Knote, Christoph; Long, Russell W.; Hoff, Raymond M.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 17(2016)
• Page Start: 10, 377
• Page End: 10, 390
• Publication Date: 2016-09-15
• Subjects: ozone -- air quality -- remote sensing -- lidar -- air quality modeling -- TOLNet; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2016JD025229
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: A high‐ozone (O3 ) pollution episode was observed on 22 July 2014 during the concurrent "Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality" (DISCOVER‐AQ) and "Front Range Air Pollution and Photochemistry Experiment" (FRAPPE) campaigns in northern Colorado. Surface O3 monitors at three regulatory sites exceeded the Environmental Protection Agency (EPA) 2008 National Ambient Air Quality Standard (NAAQS) daily maximum 8 h average (MDA8) of 75 ppbv. To further characterize the polluted air mass and assess transport throughout the event, measurements are presented from O3 and wind profilers, O3 ‐sondes, aircraft, and surface‐monitoring sites. Observations indicate that thermally driven upslope flow was established throughout the Colorado Front Range during the pollution episode. As the thermally driven flow persisted throughout the day, O3 concentrations increased and affected high‐elevation Rocky Mountain sites. These observations, coupled with modeling analyses, demonstrate a westerly return flow of polluted air aloft, indicating that the mountain‐plains solenoid circulation was established and impacted surface conditions within the Front Range. Key Points: Thermally driven mountain‐plains circulation and polluted return flow aloft exacerbated poor air quality in Colorado's Front Range Ozone and wind observations are utilized to provide a high‐resolution characterization of the air quality episode Simulations further suggest the downward transport of ozone to sites within the Front Range