Major fraction of arctic and polar cloud condensation nuclei (CCN), upon which cloud droplets form, are of secondary origin, i.e., they are formed from gas phase via homogeneous nucleation and subsequent cluster growth by condensation of low volatile vapours. The low volatile vapours required in the process are formed in gas phase oxidation of both biogenic volatile compounds and anthropogenic air pollutants. Understanding the pathways from biological processes and human activities to secondary aerosol and CCN formation is crucial in understanding especially the rapidly changing Arctic system.
Unfortunately, the aerosol and CCN formation pathways and exact connections between the biosphere and clouds in the arctic are only vaguely understood. The detailed nucleation and growth mechanisms including the nature of condensing vapours, their chemical formation mechanisms and molecular steps of cluster formation have remained largely unresolved.
In our recent studies performed in Antarctica, Greenland and Svalbard we have been able to shed light on these processes. In this talk we discuss the secondary aerosol formation in general with the focus in the fresh data from both poles and the role of sulfuric acid, ammonia, iodic acid and highly oxidized organic molecules (HOM) as well as the effect of air ions in polar secondary aerosol nucleation and growth.
Lectures Archive: http://vimeo.com/bgcatm/videos/