Classifying low elevation parcels of high ozone above the surface layer : Residual, Stratospheric, or Long range transport?

High concentrations of ozone at low elevations in the Earth's atmosphere can result from several emission and transport phenomena. Identifying the atmospheric origin of air parcels with elevated ozone concentrations is important for understanding regional and global air quality. During the 2014 NASA Student Airborne Research Program (SARP), airborne data was collected around the Los Angeles Basin in Southern California from the NASA DC-8 flying laboratory. Aerosol size distribution measurements were collected with a Droplet Measurement Technologies Ultra-High Sensitivity Aerosol Spectrometer DMT-UHSAS, while trace gas measurements were made via PTG (Photochemical Trace Gas) and Whole Air Sampling. To classify air parcels with high ozone concentrations, a vertical profile analysis was implemented to compare the height of the Planetary Boundary Layer (PBL) and tropopause height to the altitude of high ozone parcels. Other analyses included aerosol particle concentration, tracers for incomplete combustion [CO]/[CO2], and relative humidity (RH). In this study, the high ozone parcels of interest were a result of long-range transport, and back trajectories using HYSPLIT indicate that the air was transported from Asia.