Abstract
Measurements of aerosol number concentrations were made to characterize the optical properties of ambient aerosol in Korea during the period from April 1996 to June 1999. In order to validate the measured data quality the optical particle counter(OPC) was thoroughly calibrated, using polystyrene latex aerosols which are especially convenient for the calibration of OPCs. Representative aerosol size distribution in size range of 0.3-25.0 ${\mu}m$ over Korea was divided by two modes, accumulation(particle diameter < 1 ${\mu}m$) and coarse mode(particle diameter > 1 ${\mu}m$). In the urban atmosphere, aerosol size distribution has peaks at the particle size of 0.4, 2, and about 6 ${\mu}m$. Surface area and volume concentration in Seoul were 300 ${\mu}m^2/cm^3$ and 110 ${\mu}m^2/cm^3$ at the particle size of ${\mu}m$, respectively. At Kosan, representative site of island and Taegwallyong as mountainous area, aerosol concentration was lower than that of Seoul as urban area. The aerosol size distributions in those remote area were not influenced by anthropogenic sources. During the Asian dust episode, 14 to 17 April 1998, the aerosol size distributions were abruptly increased in surface area and volume concentrations of coarse mode aerosols which have the particle diameter of 2-3 ${\mu}m$. The surface area and volume concentrations, 540 ${\mu}m^2/cm^3$ and 210 ${\mu}m^2/cm^3$ during the Asian dust episode correspond to two times higher than those of normal state. Thus result during the Asian dust episode should be applied to determine the characteristic size distribution of the dust particles.