Lidar and Aircraft Profiling of Ozone above the Central San Joaquin Valley during the California Baseline Ozone Transport Study (CABOTS)

The California Baseline Ozone Transport Study (CABOTS) was conducted in the late spring and summer of 2016 to investigate the influence of long-range transport and stratospheric intrusions on surface ozone (O₃) concentrations in California with emphasis on the San Joaquin Valley (SJV), one of two “extreme” ozone non-attainment areas in the U.S. One of the major objectives of CABOTS was the characterization of the vertical distribution of O₃ and aerosols above the SJV to aid in the identification of elevated transport layers and the assessment of their surface impacts. To this end, the NOAA Earth System Research Laboratory (ESRL) deployed the Tunable Optical Profiler for Aerosols and oZone (TOPAZ) mobile lidar to the Visalia Municipal Airport (VMA, 36.315°N, -119.392°E) in the central SJV between 27 May and 7 August 2016. Here we summarize the TOPAZ ozone and particulate matter backscatter measurements made during late spring (27 May to 18 June) and mid-summer (18 July to 7 August) intensive operating periods and compare the observed distributions to co-located in-situ surface measurements and nearby regulatory monitors, and to airborne measurements from the University of California at Davis/Scientific Aviation Mooney and NASA Alpha Jet Atmospheric eXperiment (AJAX) research aircraft. Our analysis shows excellent agreement between the lidar and in-situ measurements, lending confidence to the use of these data sets for more detailed analyses.