Aerosol Radiative Effects observed on the Coast of the Japanese Sea (Tango peninsula) during ACE-Asia

The characterization of the optical properties of the atmospheric aerosol as well as its size-resolved chemical composition is on of the main objectives of ACE-Asia. This is necessary to constrain the radiative forcing by the Asian aerosol, which will become more important as emissions in this area are predicted to increase dramatically. We set up a monitoring station on the coast of the Japanese Sea (Tango Peninsula, Kyoto Prefecture) for the measurements of aerosol optical and chemical properties as well as sky radiation during ACE-Asia in spring 2001. The instrumentation at Tango includes a 3-wavelenght nephelometer (TSI 3563), an OPC (RION KC-01D), a pyrheliometer (EKO MS-53), a 5-wavelength sunphotometer (EKO MS-110A), and a pyranometer (EKO MS-801). The sunphotometer also has a near infrared channel (938 nm) for evaluations of precipitable water; visible channels are used to retrieve aerosol optical depth and Ångström exponents. Filter sampling is performed collocated to the optical measurements for subsequent analysis of elemental and ionic composition of the aerosol. Filters are also analyzed by the integrating plate method for measurements of aerosol absorption coefficients. Size-resolved chemical composition obtained from low-pressure impactor samples are used to calculate aerosol optical properties and compare them to directly measured optical properties. Quality checked parameters are henceforth input into a radiative transfer model (MODTRAN 4.0) to calculate the radiative forcing of the aerosol. This enables us to evaluate which chemical species control the optical properties and radiative forcing of the aerosol. We also compare the radiative impact of clear days with days with heavy dust loadings. >http://aerosol.energy.kyoto- u.ac.jp/~hoeller/ACEmineyama.html</a>