The overarching goal of the project is to determine how emissions from oil and gas extraction change O3 production at the local, continental and global scale. The work will address the following questions: 1. What are characteristic O3 production rates and efficiencies in air masses influenced by emissions from oil and gas production? 2. To what extent have emissions from oil and gas production impacted the extent of NOx versus NMVOC limited O3 production? 3. Through which chemical pathways do emissions from oil and gas production propagate most efficiently to global O3 production? 4. How do emissions from this sector affect radiative forcing through perturbations to tropospheric O3, methane, and remote aerosol formation? In summer 2015 and spring 2016, the project will quantify O3 production rates, sensitivity to emissions and aspects of reactive nitrogen partitioning at the NOAA BAO tower in northeastern Colorado. During the two measurement intensives, a suite of instrumentation will characterize the surface photochemical environment and determine what controls local O3 production. Specifically, measurements of OH reactivity will be made along with NO, NO2 and J(NO2) in order to calculate O3 production rates, which will be compared to direct measurements of O3 production with a new instrument.