Aerosol optical properties during Asian dust storm episodes in South Korea

Abstract

¶Aerosol optical depth (τaλ) is the most comprehensive variable to characterize aerosol, assess atmospheric pollution and make atmospheric corrections to satellite remotely sensed data from ground-based instruments. The aerosol optical properties in Korea peninsula observed at both Kwangju and Anmoyondo during the Asian dust period (March–May) have been presented in this study. Aerosol optical depths at all wavelengths showed a sharp increase during major dust outbreak in spring when compared with the average for the season. For example at Kwangju, aerosol optical depths increase from the spring average value of 0.43±0.02 at 501 nm to values >0.70 during major dust event days in 1999 and 2001. Daily mean Angstrom exponents (α) computed at both sites show dramatic changes from high values to low values on dust day periods with a sharp increase in the single scattering albedo. The study also revealed that the observed direct normal solar irradiance and diffuse horizontal irradiance during days with increased dust pollution levels is capable of reducing direct solar radiation by as much as 28% and a corresponding increase of 14% in diffuse solar irradiance during cloudless and windless days.