Twenty-six balloon-borne ozonesondes were launched near the north shore of central Long Island in the summers of 2018 and 2019 as part of the Long Island Sound Tropospheric Ozone Study (LISTOS). While surface concentrations of ozone are routinely monitored, ozone aloft is infrequently measured, but critical for a full understanding of ozone production and transport. Special attention is given to the lower troposphere from the surface to about 2 km altitude. The observed vertical ozone profiles are presented and analyzed with additional data sources and modeling tools, including LiDAR wind profiles from the New York State Mesonet, back trajectories based on 3 km resolution High-Resolution Rapid Refresh (HRRR) model data, and surface data, aircraft observations, sonde, and ozone LiDAR measurements from other LISTOS participants. The cases analyzed in detail illustrate events with high observed ozone, often with pronounced vertical structure in the profile. Specifically, easily discernable layers are identified with ozone excursions of up to 40 ppbv over short vertical distances. The analysis indicates that meteorological processes can combine to generate the observed vertical profiles. Hot, sunny days with high pressure systems are accompanied by high precursor emissions due to increased power demands, plentiful radiation for photochemistry, and stagnation of synoptic winds. These in turn allow shearing due to meso- and smaller scale flows like low level jets and sea-breeze/shore-breeze circulation to become dominant and produce the complex vertical layered structure observed. The five cases presented illustrate these processes.
