Properties and Distributions of Aerosol Particles Transported from Asia to the West Coast of the United States During ITCT 2002

During the Intercontinental Transport and Chemical Transformations experiment in April and May, 2002, airborne measurements were made of particle microphysical and chemical properties and of trace gases. Layers of air containing enhanced number and mass concentrations of particles transported from Asia were encountered near the West Coast of the United States on several flights. During the most concentrated events, the aerosol layers were found at different altitudes than were those containing enhanced concentrations of CO, NOy, and organic tracers of biomass and anthropogenic emissions. This vertical separation suggests different sources and/or different transport processes for the two layer types. Particles within the aerosol-rich bands were significantly enhanced in fine and coarse particle mass relative to surrounding air. The sources and chemical characteristics of the different layers will be evaluated using trajectory studies and measurements of trace gas composition and single particle composition determined from laser ionization/time-of-flight mass spectrometry.