University of Maryland and NOAA/ARL Collaboration over the Years: Learning how Weather, Climate and Chemistry Conspire to Create Air Pollution.

Understanding the origins and formulating solutions to problems such as photochemical smog, greenhouse gas emissions, haze, and environmental justice requires a team effort because weather drives day-to-day variability but and chemistry drives the composition. Both are subject to the forces of climate change. Over the past four decades, ARL and UMD have worked together to use the best tools available for theory and experiments. We will review the measurement campaigns for short-lived air pollutants and climate forcers, as well as numerical simulations for transport and chemistry. Findings range from the transition from VOC to NOx-limited ozone production, why there is more ozone over the Chesapeake Bay than over surrounding land, how the Bay breeze can cause local smog episodes, how the Urban Heat Island relates to lost tree cover and exacerbates pollution, and the interaction of aerosols and UV radiation. New projects include determining the origins of methane from clusters of back trajectories, evaluating emissions inventories with atmospheric measurements, and the long range transport of forest fire smoke to our area.