Understanding the Air We Breathe: Atmospheric Composition in Urban and Arctic Environments

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The overarching goal of my research is to improve our understanding of the chemical and physical processes that determine atmospheric composition and drive atmospheric change, knowledge that is essential for informed policy-making. To achieve this goal, my group develops and uses spectroscopic instruments and data analysis tools to measure atmospheric trace gas concentrations, and we collaborate with atmospheric modellers in the interpretation of these measurements. This proposal describes an integrated research program motivated by scientific questions related to the troposphere, a chemically complex region of the atmosphere where gases from natural and anthropogenic sources undergo transport and chemical processing on similar time scales. Changing emissions associated with increasing population, energy use, industrial activity, and agriculture are changing the atmospheric burden of pollutants and greenhouse gases, thus affecting air quality and climate. The Arctic is a major receptor for pollutants emitted at mid-latitudes, but uncertainty exists regarding sources, further complicated by changes in the global distribution of emissions in recent decades. The proposed research has four short-term objectives, which motivate four distinct projects: (1)To characterize the origins of urban pollution events due to local sources and long-range transport, and to quantify the impact of these episodes on tropospheric composition. (2)To determine the impact of intensive agricultural practices on ammonia and urban air quality, with a focus on Paris and Toronto as benchmark case studies. (3)To quantify urban emissions of greenhouse gases and track emission anomalies and changes over multiple timescales. (4)To investigate the determinants of air quality in the Arctic, assessing the relative contributions of anthropogenic pollution and biomass burning from Asia, Europe, North America, and local sources. To achieve these goals, we will measure trace gas concentrations at urban (Toronto), rural (Egbert), and remote Arctic (Eureka) sites, while also contributing the resulting measurements to international observing networks and using them to validate new data products from satellite missions. This program will support ten undergraduates, four graduate students, and one postdoctoral fellow. They will acquire technical skills associated with the deployment, operation, and maintenance of sophisticated instrumentation, and scientific skills associated with the numerical analysis and interpretation of atmospheric measurements. They will also gain communications skills through writing up and presenting their research, and leadership, teamwork, and problem-solving skills by taking responsibility for instruments, fieldwork, and collaborations. This combination of broad training and transferable skills will equip them well for careers in academia, government, and the private sector.