Using carbon monoxide (CO) as a relatively conserved tracer this project investigates temporal and spatial variations on a global scale of an important atmospheric oxidant, the hydroxyl radical (OH). These two species are closely coupled since the reaction of CO with OH is the most important loss process for atmospheric CO. The first element of the project involves monitoring isotopically labeled 14CO abundance at a tropical, clean air sampling site in each hemisphere, in conjunction with similar measurements at mid- and high-latitude sites in each hemisphere through collaborations with other groups, with data analyzed and interpreted in terms of advanced 3-D general circulation model simulations with the objective of improving our understanding of the oxidative capacity of the atmosphere. The second element of the study entails using stable isotope ratios of carbon and oxygen and mixing ratios of CO measured in air samples extracted from firn and ice cores to determine the southern hemisphere CO source strength from biomass burning in pre-industrial times. Broader impacts are addressed by providing a significant advance in our understanding of the oxidizing capacity of the atmosphere, and the education of young atmospheric scientists in an environment of international collaboration. Data from this study will provide powerful constraints on the atmospheric CO budget, and provide new information on global OH behavior - each having implications for climate change and global policy. The project education plan includes research opportunities for graduate students and undergraduates - including women through the Women in Science and Engineering (WISE) program.
