This seminar talks about how atmospheric nanoparticles (aerosols) adversely affect human health, perturb Earth’s climate and degrade 
visibility.
Organic aerosol globally comprises a significant fraction (20-90%) of the submicron particle mass. Three-dimensional chemical transport models often significantly under-predict the concentration and oxidative state of organic aerosol, suggesting that today’s understanding of organic aerosol is incomplete.
Dr. Hildebrandt will present results from laboratory experiments and ambient measurements which shed light on organic aerosol formation, the interaction of different organic aerosol types, and their chemical transformation (aging).
Firstly, aerosol production experiments using a state-of-the-art environmental chamber showed that aerosol mass yields from anthropogenic organic aerosol precursors are much higher than previously reported. Secondly, her team developed a new experimental method to understand the interaction of organic aerosol from different sources. The results are consistent with pseudo-ideal mixing of anthropogenic and biogenic organic aerosol components at equilibrium.
Finally, her team’s measurements at a remote coastal site suggest that the photochemical age of organic aerosol may be just as important as the aerosol source in understanding its concentrations and characteristics. All of these findings have been used to more accurately represent organic aerosol in chemical transport models. Results from the updated model agree well with observations of organic aerosol concentrations and approximate oxidative states in highly polluted as well as pristine environments.