10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Modification of the Versatile Aerosol Concentration Enrichment Factor System (VACES) for Cloud Condensation Nuclei Concentrator Purposes
CARMEN DAMETO DE ESPAÑA, Anna Wonaschuetz, Gerhard Steiner, Harald Schuh, Constantinos Sioutas, Regina Hitzenberger, University of Vienna
Abstract Number: 489 Working Group: Clouds and Climate
Abstract The activation of atmospheric aerosol particles into cloud droplets is fundamental for cloud formation. Cloud condensation nuclei (CCN), a subset of the atmospheric aerosol, constitute one of the largest uncertainties in estimating global climate change. The ability of atmospheric aerosol particles to act as CCN depends on many factors, including particle size, chemical composition, and meteorological conditions. To enlarge the knowledge on CCN, it is essential to understand the factors leading to CCN activation. For this purpose, a versatile aerosol concentrator enrichment factor system (VACES; Kim et al., 2001a; Kim et al., 2001b) has been modified to select CCN at different supersaturations. VACES allows for sampling of CCN particles without altering their chemical and physical properties. The redesigned VACES enriches CCN particle concentrations by first passing the intake flow to the saturator and then to the condenser. The activated particles are concentrated by an inertial virtual impactor, and then returned to their original size by diffusion drying. For the calibration, the saturator temperature was fixed at 50°C and the condenser temperature range was varied from 0°C to 40°C to obtain the activation curves for the different particle sizes. Knowing the activation dimeter, it was possible to calculate the supersaturation. Calibration results have also shown that CCN concentrations can be enriched by a factor of approx. 16. This correlates to the theoretical results. The theoretical enrichment factor is represented by the inlet main flow divided by the outlet minor flow which are 100 lpm and 5 lpm respectively.
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