Aerosol Size Distributions and Optical Properties during Severe Asian Dust Episodes Measured over South Korea in Spring of 2009-2010

Abstract

Measurements of PM 10 mass concentration, aerosol light scattering and absorption coefficients as well as aerosol size distribution were made to characterize the aerosol physical and optical properties at the two Korean WMO/GAW regional stations, Anmyeondo and Gosan. Episodic cases of the severe Asian dust events occurred in spring of 2009-2010 were studied. Results in this study show that the aerosol size distributions and optical properties at both stations are closely associated with the dust source regions and the transport routes. According to the comparison of the PM 10 mass concentration at both stations, the aerosol concentrations at Anmyeondo are not always higher than those at Gosan although the distance from the dust source region to Anmyeondo is closer than that of Gosan. The result shows that the aerosol concentrations depend on the transport routes of the dust-containing airmass. The range of mass scattering efficiencies at Anmyeon and Gosan was 0.50~1.45 and 0.62~1.51 m 2 g −1 , respectively. The mass scattering efficiencies are comparable to those of the previous studies by Clarke et al. (2004) and Lee (2009). It is noted that anthropogenic fine particles scatter more effectively the sunlight than coarse dust particles. Finally, we found that the aerosol size distribution and optical properties at Anmyeondo and Gosan show somewhat different properties although the samples for the same dust_episodic events are compared. 1. 서 론 대기 중에 부유하는 에어러솔은 지표로 입사하는 태양 복사를 흡수 또는 산란시키거나, 구름 응결핵 (cloud condensation nuclei)으로 작용하여 구름의 양과 수명을 변화시키는 과정을 통하여 지구-대기의 복사 평형에 영향을 준다 (Charlson et al., 1992). 또한 대