UC San Diego

Aerosol particles impact global climate in large part by acting as cloud condensation nuclei (CCN) and seeding cloud formation events in the atmosphere, which alters the Earth’s albedo. The cloud formation ability of aerosol particles is determined by their water uptake tendencies, which is defined by their chemicophysical properties. Detailed composition information, such as the distribution of chemical components within the particles know as mixing state, is therefore essential for assessing the impact of aerosols on climate. To date, such information remains elusive for small (< 50 nm) particles due to a paucity of high throughput analytical measurement techniques.

In this dissertation I describe advances in the development and application of novel methodologies for probing aerosol mixing state and composition via direct hygroscopicity measurements of highly-representative, laboratory-generated sea-spray aerosol.

First, I developed a generalizable basis set analysis to establish direct measurements of aerosol hygroscopicity as a high-throughput and robust technique to extract mixing state information for small particles. Second, I constrained the basis set analysis with measurements of pure chemical mimics in a laboratory setting to probe the sensitivity and recovery efficiency of chemically diverse models, and then applied the analysis to complex laboratory and ambient field data to quantify the diversity in composition, according to hygroscopicity. Third, I utilized traditional SR-CCN measurements to validate a proposed mechanism by which soluble organics in the ocean are enhanced in resulting sea-spray aerosols (SSA).