Revealing the Formation and Control of NYC Downwind Coastal High Ozone via New TEMPO Observations

Extreme ozone events along Long Island's south shore—a key downwind region of New York City—remain poorly understood due to limited spatial observations. We show that the new geostationary TEMPO satellite enables hourly tracking of urban plume transport, dispersion, and ozone formation across complex coastal environments. Using TEMPO data, we (a) traced precursor emission transport and processing, (b) reconstructed high ground-level ozone using hourly ozone production rates, and (c) evaluated targeted emission control strategies. The reconstructed ozone patterns matched surface observations well. Ozone production analysis revealed nearly equal contributions from formaldehyde and NO₂, with spatial variability reflecting changing chemical sensitivity regimes. The sensitivity of O₃ to precursor reduction test suggested that VOC-focused controls are more effective than NO_x under current conditions. These results provide a mechanistic framework for diagnosing and managing coastal ozone pollution and demonstrate the transformative value of geostationary satellite observations for regional air quality management.