Research:
Atmospheric Chemistry — A chemical perspective on the effects of human activity on the Earth's atmosphere and on exchanges between the atmosphere and biosphere
Professor Cohen's research focuses on developing and applying new experimental and modeling strategies for understanding the chemical composition of the Earth's atmosphere now and in the past and for predicting future changes. Current research focuses on the role of nitrogen oxides and on the isotopes of water. Laboratory, ground-based, airborne and space-based measurements are combined with modeling to understand the atmospheric residence time of nitrogen oxides, their impact on oxidants on regional and global scales, their interactions with the biosphere and their consequences for aerosol properties. Laboratory and field studies of water isotopes are used to understand cloud properties and to diagnose the regional and global behavior of the hydrologic cycle. Development of instrumentation that permits detection of previously unobserved chemicals or those chemicals whose distribution is poorly quantified continues to be at the core of this research program.