Mobile laboratory measurements of high surface ozone levels and spatial heterogeneity during LISTOS 2018: Evidence for sea breeze influence

The Long Island Sound Tropospheric Ozone Study (LISTOS) was organized to investigate ozone formation and transport in the New York City metropolitan area and locations downwind. During LISTOS, the University at Albany Atmospheric Sciences Research Center (ASRC) mobile laboratory was used for measuring surface O-3, NO2, and aerosol number and mass concentration. Sharp O-3 concentration gradients, with Delta O-3 Delta y(-1) over 15 ppb km(-1), were measured both at and near the land-water interface and on the highway on days characterized by high regional O-3 concentrations. These large O-3 gradients at or near the land-water interface, and in air masses relatively low in NO2, are shown to be influenced in part by the transport of highly oxidized air masses via sea breeze circulation and convergence with gradient flow. On the highway under regionally high O-3 concentrations, strong anticorrelation (R-2 = 0.78, p < 0.05) between O-3 and NO2 and an absolute slope less than 1 suggested that O-x concentrations (O-3 + NO2) increased with increasing NO2. Overall, the on-road measurements made during LISTOS help to better characterize the interaction between the emitted pollution and the meteorological conditions on Long Island, thereby having potential policy implications.