Recent investigations based on measurements of aerosols in ambient air provide evidence that film drops from bursting bubbles on the ocean surface produce high concentrations of primary, sub-micron, organic-rich aerosols with potentially important implications for cloud properties and climate feedback. If bursting bubbles on the ocean surface are a major primary source for hygroscopic, organic-rich, sub-micron aerosol over the world's oceans, then current models that do not consider these pathways may substantially overestimate both the importance of aerosol nucleation as a source for cloud condensation nuclei (CCN) and the associated indirect climate forcing. However, the long lifetimes of sub-micron aerosols (many days) coupled with the rapid chemical transformation of fresh marine aerosols (seconds), seriously constrain reliable differentiation based on measurements in ambient air of organic contributions from primary (mechanical) versus secondary (condensation) pathways involving marine, anthropogenic, and biogenic precursors.
This project is one component of a larger (already ongoing) investigation of the influence of sea-salt aerosol on atmospheric chemistry and climate. The overall goals of the larger research effort are to evaluate 1) the influences of halogen radicals on tropospheric O3, oxidized S, reactive N, and corresponding oxidative capacity and 2) the relative importance of primary marine aerosol as cloud condensation nuclei (CCN). The principal objective of this SGER project is: To develop a reliable parameterization for the chemical and physical characteristics of primary size-resolved marine aerosol as functions of wind velocity and dissolved organic carbon (DOC) content of the surface ocean that is suitable for application in the Community Climate System Model (CCSM) and other global model systems. Completion of this effort is a critical prerequisite for the CCSM priority of developing reliable aerosol-cloud parameterizations to address the indirect effect of aerosols.
Broader Impacts. This project will provide support for one graduate student and the analysis will be incorporated into his dissertation. Results will also contribute to the development of a reliable predictive capability for the production and indirect radiative effects of tropospheric aerosols and the associated influences on Earth's climate.
