Mobile Laboratory Measurements of Ozone, NO2, and Submicron PM Downwind of NYC during the 2018 LISTOS Field Intensive

The Long Island Sound Tropospheric Ozone Study (LISTOS) project 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 the surface O₃, NO₂, and aerosol number and mass concentration. Sharp O₃ concentration gradients, with ∆O₃ ∆y^-1 over 10 ppb km^-1, were measured both at the shoreline and on the highway on days characterized by high regional O₃ concentrations. These large O₃ gradients at the shoreline and on the highway were likely due in part to the sea breeze circulation and VOC-NO_x-O₃ photochemistry, respectively. On the highway under regionally high O₃ concentrations, strong anticorrelation (r²=0.84, p<0.05) between O₃ and NO₂ indicated that the O₃ production regime was NOx-saturated, and the positive relationship (r²=0.90, p<0.05) between O_x (O₃+NO₂) and NO₂ suggested a NOx-independent regional contribution to the O₃ level (about 90 ppb). Moreover, the days influenced by the long-range transport of biomass burning plumes showed a relatively low O₃ concentration (generally below 70 ppb) and an enhanced aerosol concentration (generally over 15 µg m^-3). Overall, the on-road measurements made during LISTOS help to better understand the interaction between the emitted pollution and the meteorological conditions on Long Island, thereby having potential policy implications.