Size distribution of atmospheric aerosols in seoul

Urban aerosol particle size distributions over the size range 0.01–1.0 μm have been determined by using an electrical aerosol analyzer at the Hanyang University in Seoul from May through to October 1984. The results indicate that the total average number distribution in the size range of 0.1–1.0 μm can be represented as the Junge distribution with dN/d(logD_p) = 28.9 D_p^?3.1. The total average surface distribution is characterized by a monomodal curve with its maximum in the vicinity of 0.13 μm, while the maximum of the total average volume distribution appears to be shifted to a larger size than that of the surface distribution showing an almost flat line for D_p 0.5 μm, which implies that a secondary maximum may exist for D_p 1.0 μm.The time development of the number size distributions for the total size range shows the minimum number in the early morning before 4 a.m. followed by a rapid increase by the morning rush hour. This development in the 0.1–1.0 μm range is characterized by the maximum numbers in the morning and evening rush hours when dense traffic and a low mixing depth coexist with high relative humidity. The photochemical production of small particles in the 0.01–0.1 μm range is verified from monthly variation of number concentration and duration of sunshine.In general the monthly development of the surface and volume distributions shows the highest values to be in spring with the lowest in summer.