Transport Dynamics Associated with Surface Ozone Concentrations in Joshua Tree National Park

Joshua Tree National Park, located in Southern California, has some of the worst air pollution within the national park system. This study investigated the transport dynamics associated with elevated ozone concentrations in the park. Measurements were conducted during the months of June and July, when ozone concentrations tend to be highest. Three portable ozone monitors were deployed to remote locations to supplement data from the three long-term monitoring stations within Joshua Tree. Raw data for each of these locations were converted into 8-hour averages to identify violations of the National Ambient Air Quality Standard (NAAQS) for ozone. To understand the transport dynamics that bring high ozone concentrations into Joshua Tree, back-trajectory calculations were performed with the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model from the Air Resources Laboratory of the National Oceanic and Atmospheric Administration. For most measurement locations within the park, ozone was generally transported in from the west. A significant amount of ozone was also transported into the park from the south.