Abstract
Massive 'bursts' in condensation nuclei (CN) concentration were recorded at a remote site on the west Irish coast during campaigns in summer 1996 and spring/summer 1997. Number concentrations of 3-7 nm diameter CN were observed to rise daily from 10 exp 2 to 10 exp 3 up to approximately 10 exp 5/cu cm for 1-3 hours. Possible chemical mechanisms for the burst phenomenon are investigated. Two approaches are adopted. First, by assuming a 20:80 sulfate:water molar composition and calculating the number distribution using data from condensation particle counters, the total mass of CN formed during a burst is evaluated. This is compared with that mass of sulfate produced by OH-initiated dimethyl sulfide (DMS) oxidation. The procedure is termed 'mass balance'. Second, a variety of chemical species are coplotted with tidal height. DMS oxidation is not believed to play a major role in CN formation at this site. None of the suite of observed nonmethane hydrocarbons or DMS showed a tidal relation. No mechanism has to date been convincingly identified for the burst phenomenon. (Author)