AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Cloud Condensation Nuclei Measurements at a High Elevation Site: Composition and Hygroscopicity
BETH FRIEDMAN, Alla Zelenyuk, Josef Beranek, Gourihar Kulkarni, Mikhail Pekour, Anna Gannet Hallar, Ian McCubbin, Joel A. Thornton, Daniel Cziczo, University of Washington
Abstract Number: 712 Working Group: Aerosols, Clouds, and Climate
Abstract Field measurements of cloud condensation nuclei (CCN) were conducted in March 2011 at Storm Peak Laboratory (elevation 3220 m a.s.l.) in Steamboat Springs, CO. Measurements of CCN number concentrations and droplet size distributions at supersaturations of 0.08%, 0.1%, 0.2%, 0.4%, and 0.7% were conducted in parallel with Scanning Mobility Particle Sizer (SMPS) measurements of size distributions and number concentrations of ambient particles. SMPS number concentrations of the overall ambient aerosol population were used to calculate the fraction of particles activating as droplets at the supersaturations studied. Single Particle Laser Ablation Time-of-Flight mass spectrometer (SPLAT II) was used to characterize number concentration, size, internal composition, and densities of individual particles present in the ambient air. κ-Köhler theory, particle size measurements, number concentrations of CCN and CN, and single particle composition measurements were utilized to predict CCN concentrations and assess particle hygroscopicity and the importance of particle mixing state in CCN activation and prediction. Case studies with detailed compositional information, as well as free tropospheric CCN concentrations, will also be presented.