Special Seminar: An Undercurrent of Change in the Pacific: Climate Dynamics with Ecosystem Impacts
Dr. Kristopher Karnauskas received his B.S. and Ph.D. in Atmospheric and Oceanic Science from the Universities of Wisconsin-Madison and Maryland-College Park, respectively, and carried out a postdoctoral fellowship within the Ocean and Climate Physics group at the Lamont-Doherty Earth Observatory of Columbia University. Kris is currently an Associate Scientist at the Woods Hole Oceanographic Institution on Cape Cod, MA. Kris' research aims to understand the dynamics of the tropical ocean and atmosphere as a coupled system, its interaction with ecosystems and with higher latitude regions, how and why the climate system has changed in the past, and how climate will continue to change in the future–both naturally and as driven by human activities. Kris has taught courses on climate in the MIT-WHOI Joint Program and at Boston College.
Analytical Chemistry Seminar: Prof. Tim Bertram
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Chemistry at Atmospheric Aqueous Interfaces: In situ Constraints on Halogen Activation at the Air-Sea and Air-Particle Interface
Prof. Tim Bertram
Reactions occurring at atmospheric, aqueous interfaces can serve to catalyze reaction pathways that are energetically unfavorable in the gas phase. The reactive uptake of N2O5, a primary nocturnal nitrogen oxide (NOx) reservoir, serves as both an efficient NOx removal mechanism and regionally significant halogen activation process through the production of photo-labile ClNO2. Both the reaction rate and ClNO2 product yield are a complex function of the chemical composition of the reactive surface. To date, analysis of the impact of N2O5 chemistry on oxidant loadings in the marine boundary layer has been limited to reactions occurring on aerosol particles, with little attention paid to reactions occurring at the air-sea interface. Here, we report the first direct measurements of the air-sea flux of N2O5 and ClNO2 made via eddy covariance in the polluted marine boundary layer. The results are combined with in situ determinations of the N2O5 loss rates to aerosol particles and interpreted within a time-dependent coupled atmosphere- ocean model.