Atmospheric aerosols: Chemistry and dynamics under natural and polluted conditions

Understanding atmospheric aerosols is important in addressing issues of local air quality, regional acidification, and global climate. However, the diversity of both the ambient atmosphere, and the aerosol particles themselves makes their study particularly challenging. Computational modeling of atmospheric aerosols provides an important tool that can aid in both revealing the fundamental properties of aerosols and in forecasting the success of regulation oriented policies. In this work the natural marine atmosphere is studied. Models are developed that help to reveal the important physical and chemical processes that govern the marine atmosphere. Insights include the sensitivity of the gas-phase oxidation of natural marine sulfur species to chemical and meteorological variables. Marine aerosol processes are also studied. Particular emphasis is placed on describing the non-linear processes that may lead to new particle formation over the ocean. The effects of pollution from international shipping on the marine atmosphere are also explored and found to be significant in much of the Northern Hemisphere. When heavily polluted conditions are encountered, different types of aerosol models are more useful. In the final section of this work, a fundamental assumption in urban air quality models is challenged by developing an efficient method for describing the dynamic evolution of aerosol particles exposed to semi-volatile species. This method allows both the accuracy of a fundamental mass transfer approach with the speed of a bulk equilibrium model.