title: The Impact of Aerosol Particle Mixing State on the Hygroscopicity of Sea Spray Aerosol.
abstract: Aerosol particles influence global climate by determining cloud droplet number concentrations, brightness, and lifetime. Primary aerosol particles, such as those produced from breaking waves in the ocean, display large particle-particle variability in chemical composition, morphology, and physical phase state, all of which affect the ability of individual particles to accommodate water and grow into cloud droplets. Despite such diversity in molecular composition, there is a paucity of methods available to assess how particle-particle variability in chemistry translates to corresponding differences in aerosol hygroscopicity. Here, an approach has been developed that allows for characterization of the distribution of aerosol hygroscopicity within a chemically complex population of atmospheric particles. This methodology, when applied to the interpretation of nascent sea spray aerosol, provides a quantitative framework for connecting results obtained using molecular mimics generated in the laboratory with chemically complex ambient aerosol. We show that nascent sea spray aerosol, generated in situ in the Atlantic Ocean, displays a broad distribution of particle hygroscopicities, indicative of a correspondingly broad distribution of particle chemical compositions. Molecular mimics of sea spray aerosol organic material were used in the laboratory to assess the volume fractions and molecular functionality required to suppress sea spray aerosol hygroscopicity to the extent indicated by field observations. We show that proper accounting for the distribution and diversity in particle hygroscopicity and composition are important to the assessment of particle impacts on clouds and global climate.
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Schill
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Collins
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Lee
authors.affiliation: Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors.forename: Holly S
authors.initials: HS
authors.lastname: Morris
authors.affiliation: Department of Chemistry, University of Wisconsin Madison , Madison, Wisconsin 53706, United States.
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Novak
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States; Scripps Institution of Oceanography, La Jolla, California 92037, United States.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Prather
authors.affiliation: Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration , Seattle, Washington 98115, United States.
authors.forename: Patricia K
authors.initials: PK
authors.lastname: Quinn
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States.
authors.forename: Camille M
authors.initials: CM
authors.lastname: Sultana
authors.affiliation: Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Tivanski
authors.affiliation: Department of Chemistry and Biochemistry, University of California San Diego , La Jolla, California 92093, United States.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Zimmermann
authors.affiliation: Department of Civil and Environmental Engineering, University of California Davis , Davis, California 95616, United States.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Cappa
authors.affiliation: Department of Chemistry, University of Wisconsin Madison , Madison, Wisconsin 53706, United States.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Bertram