The Red Butte Canyon Ozone Network: leveraging existing infrastructure to probe background concentrations, canyon flows and stratospheric oxidant exchange

The Salt Lake Valley (SLV) experiences frequent prolonged pollution episodes impacting the health of the ~1 million residents of the valley. These health effects include an array of respiratory and pulmonary problems, chiefly among susceptible populations and those participating in outdoor activities (Devin et al., 1997; Parmet et al., 2003). The unique topography of the SLV results in two distinct air quality seasons, with elevated fine particulate matter (PM2.5) in the winter, and significantly elevated ozone (O3) levels in the summer. These pollution episodes commonly exceed the Environmental Protection Agencies (EPA) National Ambient Air Quality Standards (NAAQS) and as a result the SLV has been declared a nonattainment area for both PM2.5 and O3 standards. Recent studies have identified O3 as the critical oxidant driving the formation of wintertime PM2.5 (Baasandorj et al., 2017, Womack et al., submitted). Thus, O3 serves as a key pollutant during both the summer and winter months. Despite the importance of O3 as both a pollutant and an oxidant, many questions remain regarding its formation, transport and roles in secondary chemical reactions. In particular, transport of O3 through the mountain canyons surrounding the SLV is poorly understood. This project would deploy a transect of reliable and accurate O3 monitoring stations throughout the Red Butte Canyon the is adjacent to the University of Utah. The Red Butte Canyon is a United States Forest Service designated Research Natural Area and already has significant monitoring resources deployed in it that this project will leverage. This network will produce a dataset with several applications ranging from: (a) probing the role of canyon flows in the transport of O3 during stratospheric injections in the summer (b) examining the exchange of O3 from the free troposphere with stagnant air in persistent cold air pools in the winter (c) the potential for using the site to assist in understanding and monitoring background O3 concentrations, and (d) examining the impact of anthropogenic activities on O3 formation,. A better understanding of these outstanding questions is central in the implementation of successful O3 mitigation policies.