Wednesday, 14 January 2009
Chemical apportionment of direct aerosol radiative forcing in Korea
Hall 5 (Phoenix Convention Center)
Shortwave direct aerosol radiative forcing (DARF) at the surface as well as aerosol optical depth (AOD) were estimated and chemically apportioned on the basis of ground-based aerosol and radiation measurements at the Gosan super-site in Korea. An aerosol optical model and a radiative transfer model (RTM) were employed to calculate the aerosol extinction coefficient and radiative flux at the surface, respectively. The calculated scattering and absorption coefficients agreed well with measured scattering and absorption coefficients. The modeled direct and diffuse irradiances at the surface were also in good agreement with the measured direct and diffuse irradiances. In this study we found that the 17-day mean aerosol radiative forcing at the surface is attributable to mineral dust (45.7%), water-soluble components (sum of sulfate, nitrate, ammonium, and water-soluble organic carbon (26.8%), and elemental carbon (EC) (26.4%). However, sea salt does not play a major role. For the cases of Asian dust and smoke episodic events on 26 April 2001, a diurnal averaged forcing was contributed by mineral dust, EC, and water-soluble components. The results of this study suggest that water-soluble and EC components as well as a mineral dust component are responsible for a large portion of the aerosol radiative forcing at the surface in the continental outflow region of East Asia.