Air Quality of Baltimore and New York City: A Conspiracy of Meteorology and Chemistry

For cities adjacent to large bodies of water, meteorology and photochemistry conspire to generate distinct air pollution problems – and opportunities for understanding and improving air quality. Convergence over the warmer land can generate changes in wind direction and speed, convection, and even recirculation when linked to subsidence over lakes, bays, or the ocean. Ozone maxima over water, seen in both numerical models and observations, arise from a combination of a shallow boundary layer, fewer clouds and greater radiative flux, as well as different sources and sinks. In this talk I will summarize the history and most recent air quality studies in the Baltimore/Washington area as well as the New York, Connecticut, Long Island Sound area. Rapid removal of the most reactive biogenic hydrocarbons, ship emissions, and the sea breeze lead to complex process resulting in air pollution events including in summer 2018 New York’s highest ozone in a decade. In situ measurements from aircraft and surface sites as well as remote sensing guide numerical simulations that help predict the efficacy of air pollution control policy with greater precision.