Using analytical chemistry to improve our understanding of the atmosphere
The influence of aerosol particles on clouds remains one of the largest uncertainties in accurately predicting the Earth’s energy balance in a changing climate system. Aerosol particles can affect the climate directly by scattering or absorbing solar radiation or indirectly by acting as cloud condensation nuclei (CCN) onto which water vapor condenses to form cloud droplets - both of which vary depending on the size and chemical composition of the particles. Surface-active compounds (surfactants) may influence the ability of a particle to act as a CCN by reducing its surface tension. Our work is on identifying the specific sources of surfactants in aerosol particles, measuring their chemical compositions, and determining their role in the atmosphere.
Influence of surfactants in marine aerosol production
One source of organic mass in atmospheric aerosol particles, which may also contain surfactants, is bubble bursting at the ocean surface caused by breaking waves. We are interested in: (1) how surfactants control and influence bubble-bursting at the ocean surface; (2) the sources, composition, and concentrations of surfactants in seawater and their regional and seasonal variations; and (3) how bubble scavenging and bursting affects surfactant properties in the resulting aerosol particles.
Composition and concentration of surfactants in aerosol particles
We sample atmospheric aerosol particles in the field and those produced from model ocean systems. We use multiple techniques to measure: (1) the composition and concentration of surfactants in fresh, primary marine aerosol particles (both generated and atmospheric); and (2) the fraction of the surfactants that partition from the seawater to the aerosol particles, comparing the composition and types in each.
Effect of surfactants on cloud droplet formation, growth, and lifetime
The chemical composition of aerosol particles can affect their ability to activate into cloud droplets through their hygroscopicity and surface tension. We are interested in: (1) the influence of surfactants on the water uptake and lifetime of individual aerosol particles; and (2) understanding the influence of surfactants on both hygroscopicity and surface tension within single particles.
Field Work and Project Involvement
North Atlantic Marine Aerosol Cruise 2016 (data)
International Collaboration in Chemistry: Measuring the Effects of Surfactants on Cloud Microphysics
Western Atlantic Climate Study 2012 (WACS)
Mt. Soledad Cloud and Boundary Layer Study 2012 (Soledad)
Eastern Pacific Emitted Aerosol Cloud Experiment 2011 (EPEACE)
Nexus between Climate Change and Air Quality in California 2010 (CalNex)
Biosphere Effects on AeRosols and Photochemistry Experiment 2007 and 2009 (BEARPEX)
International Chemistry Experiment in the Arctic Lower Troposphere 2008 (ICEALOT)