Characteristics of particle formation events in the coastal region of Korea in 2005

Measurements of particle number size distribution with diameters ranging from 10 to 487 nm, meteorological parameters and two pollutant gases (ozone (O3) and sulfur dioxide (SO2)) were made to investigate characteristics of new particle formation and growth events at the western coastal region of South Korea in 2005. Among 291 days of Scanning Mobility Particle Sizer (SMPS) measurements, 56 days (about 19.2%) were identified as particle formation events. In particular, 48 days were classified into significant nucleation events. During the cold season, the events are most frequently occurred. Particle growth rates during the cold season were in the range of 1.0–15.7 nm h−1 with the mean of 5.9 nm h−1. Most of the nucleation events were observed at the conditions of high UV-B irradiance (>50 mW m−2) and low relative humidity (<60%). The SO2 concentration on nucleation event days was higher than that of non-event days, whereas the O3 concentration between event and non-event days did not show any significant difference. The nucleation events were also found to be associated with a sea breeze blown from northwest or southwest direction, indicating that the air masses may be originated from the Asian continent and accompanied with cold air outbreak behind cold fronts.