Abstract ID: 282

Cloud condensation nuclei from biogenic and anthropogenic sources over the Amazon Basin

We measured the concentrations and properties of cloud condensation nuclei (CCN) over the central Amazon Basin near Manaus during February and March 2008. The measurements were conducted as part of the AMAZE-08 (Amazonian Aerosol Characterization Experiment) campaign. CCN were determined as a function of particle size and supersaturation by first selecting a narrow size fraction using a differential mobility analyzer and then analyzing the selected particles over a range of supersaturations for their CCN activity using a DMT CCN counter. The CCN concentrations were quite low (a few hundreds) during unpolluted conditions, but increased significantly during some pollution events that may have originated from long-range transport or from nearby Manaus. The solubility of the aerosols, represented by average hygroscopicity parameters (kappa) in the range of 0.1-0.2, was lower than what has been commonly observed in polluted environments. The hygroscopicity of the particles decreased with increasing organic mass fraction (and decreasing inorganic ion content). The results from the AMAZE-08 campaign will be compared to previous measurements over Amazonia and to results from other regions.

Session:  Feedbacks to Climate - Emissions of natural and biomass burning particulates from vegetation and their effects on ecosystems and climate.

Presentation Type:  Oral