Abstract
Aerosol particle dynamics were observed in the summertime marine boundary layer 10 km offshore of the northeast American coast. Particle dynamics were observed using a scanning mobility particle sizer for observation of the number-based size distribution, and a quadrupole aerosol mass spectrometer (Q-AMS) for quantification of the mass-based size distributions and bulk particle mass loadings of nonrefractory components. Analysis was supported by meteorological data, extensive trace gas data, and aerosol Berner impactor data. No new particle formation with clearly identifiable growth of ultrafine particles was identified. One event exhibited a clear banana-shaped evolution of the number-based size distribution. However, the conditions were nonstationary in various aspects. In some phases of the event, particle growth mechanisms could not be confirmed despite an increase of the geometric mean of the number-based size distribution. Air mass changes and dilution of boundary layer air are possible causes for the observed dynamics. The observation of particle number-based size distributions did not provide sufficient proof for the occurrence of a growth event. Continental organics were the predominant species driving particle dynamics. The contribution of industrial sulfate also was important. The mass size distributions of the Q-AMS and the impactor agreed reasonably well for the species analyzed. Overall, we conclude that a detailed analysis of aerosol plume dynamics and temporal evolution, including both meteorology and chemistry, reveals much more detail about the aerosol evolution that could be deduced from the number size distribution alone.