A Detailed Look at Oil and Gas Impacts on Air Quality in the Colorado Northern Front Range (Invited Presentation)

The Colorado Northern Front Range Metropolitan Area (NFRMA), encompassing the Denver metropolitan area, has been designated as a Federal Non-Attainment Area since 2007 for violation of the National Ambient Air Quality Standard for 8-hr ozone of 75 ppbv, with violations primarily occurring in the summer months. Air quality in the NFRMA is impacted by emissions from a wide variety of very diverse sources. These include the transportation sector, power generation, agriculture and livestock operations, and natural emissions from vegetation. The NFRMA further has experienced rapid expansion of oil and gas extraction in recent years due to advances in hydraulic fracturing technology. The Denver-Julesburg Basin (DJB), northeast of Denver, is one of the most intensively drilled fields in the United States. Large uncertainties exist in the quantification of this emission source and its impacts on the air quality of the region. The Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ) was designed to quantify the factors controlling surface ozone in the NFRMA and determine whether current and planned emission controls are sufficient to reduce ozone levels below standards. The experiment was conducted simultaneously with the 2014 NASA DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) intensive campaign, and employed a coordinated set of ground-based, aircraft-based and satellite measurements. During FRAPPÉ, fifteen flights were performed between July 26 and August 17, 2014, on board the NCAR/NSF C-130 research aircraft, which was equipped with a comprehensive gas phase photochemistry and aerosol payload. The C-130 flights covered much of the State of Colorado. Numerous ground sites and mobile labs deploying in-situ and remote sensing technology were taking measurements simultaneously, and the fully equipped NASA P3, B-200, and Falcon aircraft flight operations were concentrated on the NFRMA itself. Together this rich data set allows characterizing the different emission sources and their impact on local air quality, the contribution of inflow of pollution, and the role of terrain-induced, complex mountain-valley circulation patterns, which can recirculate polluted air, exacerbate high ozone events and contribute to pollution transport into pristine mountain areas West of the NFRMA. This talk will present findings from the FRAPPÉ and DISCOVER-AQ Science Team as they relate to oil and gas activities including data analysis as well as modeling studies with the regional chemical transport model WRF-Chem and others. We will discuss first results on the characterization of the emissions from oil and natural gas activities and comparisons to existing emission inventories, assessments of their contribution to OH reactivity and ozone production, and analysis of the transport and chemical evolution of oil and gas emissions into urban and pristine areas.