Total Column Radiative Forcing by Aerosols During the ACE-ASIA Campaign

Comprehensive measurements including the solar insolation at the surface as well as the aerosol column optical depth were made during the intensive field phase of the ACE-ASIA field project. These measurements, in conjunction with aerosol-free model simulations are used to determine the radiative forcing at the surface for the visible, near-infrared, and total solar spectral bandpasses. The predominant sources and compositions of the aerosols present in the measurement region located at Cheju Island, Republic of South Korea, ranged from anthropogenic "pollution" from large cities in China, Korea, and Japan as well as natural "yellow dust" transported from the Gobi desert area. The surface radiation measurements are used to characterize the overall climatic response to the combination and variability of the magnitude of the atmospheric aerosols. Analyses show that the diurnally averaged surface radiative forcing due to the aerosols is approximately -82.6 W/m2 per unit optical depth at 500 nm for the total solar broadband spectrum with a roughly equal contribution from the visible (-41.7 W/m2) and near-infrared (-44.0 W/m2) portions.