92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 5:15 PM
Aerosol and CCN Concentration in the Megacity of Seoul During 2004–2010
Room 244 (New Orleans Convention Center )
Jong Hwan Kim, Yonsei University, Seoul, South Korea; and W. J. Kim and S. S. Yum

Submicron aerosol number concentration (NCN) and the size distributions were measured in a continuous manner at Yonsei University located near the center of Seoul, South Korea, during 2004-2010. Cloud condensation nuclei number concentration at 0.6% supersaturation (NCCN) was also measured during 2006-2010. The number of days with reliable measurement data was 787, 891 and 589 days, respectively. The NCN, geometric mean diameter of aerosols (Dg) and NCCN are in the range of 18094±7149 cm-3, 49±10 nm, and 5272±3143 cm-3. The average NCCN is comparable to the one measured at an island about 200 km to the west of Seoul, which is a downwind region of Shandong Peninsula where Chinese industries are heavily located. Both NCN and NCCN had strong tendency to reach their daily minimum value between 3 and 5 AM throughout any time of the year. The values of NCCN/NCN and Dg tended to reach their daily maximum during these hours. NCN and Dg showed strong positive and negative correlation (r2 > 0.80), respectively, with the traffic amount at the major road about 500 m away from the instrument room. However, NCCN showed much weaker correlation (r2<0.30). In terms of seasonal variation, the highest NCN, NCCN and NCCN/NCN were all found during winter and the lowest NCCN, NCN and NCCN/NCN during autumn. Between April and July, particle formation and growth events occurred in more than 10% of the total measurement days and the most frequent month was May with about 25%. On the other hand, the event was found less than 5% of the measurement days between December and January.

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