AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
New Particle Formation in an Urban Atmosphere: Seasonal Dependence and Influence of Air Mass Origin
ANNA WONASCHUETZ, Julia Burkart, Richard Haindl, Julia Palmetshofer, Georg Reischl, Gerhard Steiner, Robert Wagner, Regina Hitzenberger, University of Vienna
Abstract Number: 330 Working Group: Urban Aerosols
Abstract Ultrafine particles in urban areas are a major concern regarding air quality and public health. Local direct emissions of small particles and new particle formation events are sources of fine and ultrafine particles, but meteorological conditions and the properties of the background aerosol moderate both production and fate of freshly produced particles. In this study, a comprehensive dataset of aerosol number size distributions spanning several years is combined with modeled air mass origin (HYSPLIT back-trajectories), weather and solar radiation data, and elemental and organic carbon analyses in order to investigate the conditions under which new particle formation events can take place in an urban environment, as well as their seasonal dependence. A second aim is to establish the extent to which air mass origin affects the properties of the urban aerosol. The shape and development of the size distributions indicate the impact of local sources. Human activity patterns are reflected in the concentrations of black and brown carbon, which serve as tracers for fossil fuel combustion and biomass burning. Pollen on filter samples indicate strong biogenic influences. First results suggest that in summer, higher sub-micrometer aerosol volume concentrations were associated with back-trajectories from the east, lower concentrations with westerly back-trajectories. New particle formation events were often, but not always, linked to diurnal peaks in solar irradiation. In winter, new particle formation events were absent, due to both higher background aerosol concentrations and lower solar irradiation. The contribution of fine and ultrafine particles to total number concentrations in winter was dominated by local anthropogenic sources.