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Differentiating natural and anthropogenic cloud condensation nuclei in the California coastal zone


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Aerosol samples were collected and cloud condensation nuclei (CCN) concentrations at five supersaturations were measured along and off the central California coast within the cloud-topped, marine boundary layer from aircraft flights during August 2007. Receptor modelling has been applied to estimate the natural versus anthropogenic source contribution of cloud condensation nuclei in this region, a region of climatically important marine stratocumulus. The results suggest that anthropogenic CCN accounted for about 50% of the CCN active at 0.3% supersaturation in this region during the measurement period.