Sources of Free Tropospheric Ozone Enhancements in CA

Sources of Free Tropospheric Ozone Enhancements in CA

Matthew Davey, Lyndon State College

Numerous free tropospheric layers with high ozone were observed during Student Airborne Research Program (SARP) 2013, SARP 2012 and California Nexus campaign (CALNEX) 2010 flights. Potential sources of these enhancements include aged regional emissions from the boundary layer, long range transport emissions (LRT) from Asia, and/or stratosphere to troposphere exchange (STE) of ozone enriched air. Events were classified by examining mixing ratios of benzene, CO, CFC-113, CH₃CL, ethyne, H-1211, HNO₃, methane, and PANs. Out of 19 enhanced plumes of ozone selected, five (26.3%) were classified as a STE event, two (10.5%) as a LRT event and twelve (63.2%) as a boundary layer event. This random sampling of free tropospheric air in the Spring and Summer over California is indicative of past research done modeling free tropospheric ozone in the area. Further research on the potential transport of this elevated, enhanced ozone to the surface could assist efforts in air quality control in the LA Basin. Modeled meteorological parameters associated with this transport would produce greater lead times in air quality forecasts.