Sources of High Ozone in the Sequoia National Park during the 2016 California Baseline Ozone Transport Study (CABOTS)

The Sequoia and Kings Canyon National Parks and the surrounding Sierra Nevada are routinely exposed to high ozone (O₃) concentrations exceeding the U.S. National Ambient Air Quality Standards (NAAQS) during the summer months. These high concentrations can adversely affect both the visiting public and the signature vegetation of these unique forests. Understanding the sources of this ozone was one of the motivations for the California Baseline Ozone Transport Study (CABOTS) conducted in the late spring and summer of 2016. As part of this study, the NOAA/ESRL mobile ozone and aerosol lidar (TOPAZ) was deployed to the Visalia, CA Municipal Airport in the central San Joaquin Valley (SJV) for two 3-week intensive operating periods: (May 29 – June 18) and (July 18-August 7). In this talk, I will describe our efforts to estimate the relative contributions of ozone transported across the Pacific from Asia and domestically produced ozone carried into the mountains by upslope flows using the vertical ozone profiles measured by the lidar and surface measurements from the U.S. National Park Service monitors at Ash Mountain (515 m asl) and Lower Kaweah (1926 m asl).