Understanding Ozone and Ozone Precursors During the OWLETS-1 Field Campaign through Model Simulations, Air Mass Trajectories, and Aircraft and Surface Observations

The Ozone-Water Land Environmental Transition Study (OWLETS-1) field mission in summer 2017 sought to understand why and how ozone tends to have higher concentrations over the lower Chesapeake Bay watershed than the surrounding land. The overarching goal of this field mission was to address ozone and its behavior in and around the Chesapeake Bay since it is an EPA regulated criteria pollutant. Measurements of O₃ and various species were collected using sensors on-board NASA’s C-23 Sherpa Aircraft and the NASA Langley Mobile Ozone Lidar (LMOL). LMOL and Sherpa observed high ozone mixing ratios over CBBT, though the data exhibit large spatial and temporal variability. The Sherpa collected observations of trace gases in the vicinity of Richmond, VA, upwind of CBBT. The data show enhanced ozone precursors near the surface, which may be attributed to nearby electric generating units. To understand the photochemistry that led to the O₃ profiles observed over CBBT, we constrain the Framework for 0-D Atmospheric Modeling (0-D F0AM) box model to measurements of ozone and its precursors acquired during the Sherpa flights to determine the ozone production regime along the flight track. We also run HYSPLIT back trajectories from CBBT and along the Sherpa flight track to determine possible emissions sources with the High-Resolution Rapid Refresh (HRRR) model as the meteorological input. Results from OWLETS-2, a follow up study to OWLETS-1 in summer 2018 located around Baltimore, MD, will be used to compare the conditions in the lower and the upper Chesapeake Bay. Finally, our new understanding of the environment in the lower region of the Chesapeake Bay will be used to provide insight into air quality issues throughout the region influenced by this watershed.