Observations of new particle formation events in the South-Eastern Baltic Sea

New particle formation and growth were observed at a coastal site (Preila station, Lithuania) during 1997 and 2000–2002. The total amount of data analysed covers 291 one-day periods, 45 (15%) of which were long-term, new particle formation days. Short-term nucleation events (from a few minutes to one hour) and long-term events (from one to eight hours) were identified. The mean particle growth rate, condensation sink and condensable vapour source rate during nucleation events were 3.9 nm h−1, 1.45 × 10−3 cm−3 s−1 and 7.5 × 104 cm−3 s−1 respectively. The average formation rate J10 was 0.4 cm−3 s−1. The nucleation events were accompanied mainly by air masses transported from the north (43%) and north-west (19%). Meteorological parameters and trace gas (O3, SO2, NO2) concentrations were also analysed. It was found that nucleation events are related to high levels of solar radiation.