Wavelength‐dependent aerosol single‐scattering albedo: Measurements and model calculations for a coastal site near the Sea of Japan during ACE‐Asia

Abstract

Wavelength‐dependent optical properties together with the size‐resolved elemental and chemical composition of the atmospheric aerosol were measured at Yasaka, Japan, near Wakasa Bay on the coast of the Sea of Japan. Observations were performed as part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) campaign during three weeks in March and April 2001. Information about the detailed chemical composition and the size distribution of the aerosol, including absorbing material, was used to model optical properties of the aerosol and compare them with directly measured properties. Continuous, size‐resolved measurements of aerosol scattering and backscattering coefficients were made at wavelengths of 450, 550, and 700 nm. Aerosol size distribution measurements were taken three times during the campaign for a period of 3–4 days each, using cascade impactors. One of the measurement periods was influenced by an intense yellow dust event originating on the Asian continent (20–25 March 2001), while the other two data sets were only weakly influenced by dust particles. The size‐resolved measurement of aerosol scattering coefficients and the chemical analysis showed that the dust was accompanied by fine accumulation‐mode particles during the dust event. The effects of the mineral dust particles on the optical and chemical properties of the aerosol are discussed, and data sets with and without desert dust influence are compared. Before the optical closure calculation a mass closure of the aerosol was performed, and the influence of the nonanalyzed fraction on the calculated optical properties of the aerosol is investigated. In general, good agreement between measured and modeled aerosol optical properties was found for the aerosol scattering and absorption coefficients, while less agreement was found for the backscattering coefficients, especially for the coarse mode of the aerosol. A distinct difference between the dust and nondust periods was found for the wavelength‐dependent single‐scattering albedo.