(593i) Organic Ccn Activity of in-Situ Samples Obtained from the Mase 2005 Campaign

Ambient water-soluble organics are long known to affect the ability of ambient aerosol to act as Cloud Condensation Nuclei (CCN). Yet to date, relatively few techniques are available to comprehensively constrain their aggregate thermodynamic properties, which in turn are required for quantifying their contribution to the aerosol indirect effect. In this study, we provide such data, by measuring the CCN activity of the soluble mass found in stratocumulus cloud water and interstitial carbonaceous aerosol collected aboard the CIRPAS Twin Otter during the Marine Stratus Experiment (July, 2005). In addition to CCN activity, surfactant properties of the collected samples are characterized with a KSV Inc, pendant drop method tensiometer. Kohler theory analysis of the measurements suggest that the water-soluble organics in all the samples are not strong surfactants, fairly soluble and with a low molar volume, similar to ammonium sulfate.