Phase Transitions of Aqueous Atmospheric Nitrate, Sulfate, and Ammonium Particles

Harvard University, Cambridge MA

Investigators

Abstract

This project extends upon previous aerosol phase behavior studies by this investigator on particle classes exerting a significant anthropogenic cooling contribution to global direct radiative forcing, and is aimed at understanding tropospheric aerosol phase behavior assessed quantitatively through combined laboratory and modeling approaches. Mixed salt crystallization experiments will be conducted to determine crystallization relative humidity on relevant model tropospheric particles, followed by optical constant measurements on solutions with the same composition. These data will then be incorporated into a global chemical transport model capable of resolving radiative forcing and chemistry. Results will have a broad scientific impact on society through improved optical constants and predictive understanding of particle phase, by reducing uncertainties in existing satellite inversion algorithms used in the global assessment of atmospheric particles, and generally increasing current understanding of how anthropogenic particles contribute to radiative forcing. Such issues are of high policy relevance with respect to the global community in terms of energy planning, production and use, the regional and long-range transport of particulate pollution, and the impact on global climate. The project supports graduate student and postdoctoral researcher involvement, and includes integration of research results into undergraduate education and outreach.