My research interests are global atmospheric composition and chemistry, and interactions of these with the biosphere and climate system. This includes the study of both particles and gases in the troposphere, their sources, sinks, transformations, long range transport and environmental impacts. I work at the intersection of modeling and observational analysis, with a strong emphasis on the integration of the two. This involves using observations of the atmosphere from all scales: from ground stations, aircraft campaigns and satellite sensors with global models of chemistry and climate.