Characteristic number size distribution of aerosol during Asian dust period in Korea

The size-separated number concentrations of aerosols ranging from 0.3 to 25 mum were observed in Seoul and Anmyon Island in the west coast of Korea du ring Asian dust period in Spring 1998. During the heavy dust period, the nu mber size distributions of aerosols observed in both places were characteri zed by decreases in small size < 0.5 mum and increase in large size between 1.35 and 10 mum, For particles in this range, there was a good correlation between number concentrations observed in both two places. The number of c oarse particles > 10 mum showed a distinct diurnal variation without a sign ificant change in amplitude, which was more pronounced in Seoul. It suggest s that coarse particles were more affected by local sources. Trajectories b ack in time showed that the air collected in Korea during dust period origi nated from desert regions in the central part of China. From these results, it was evident that increased particles in the range of 1.35-10 mum during dust source period represented mineral components, which originated possib ly from the dust source regions. (C) 2001 Elsevier Science Ltd. All rights reserved.