Title: Ace-Asia: Gosan measurements of column direct and downwelling diffuse broadband radiation and spectral optical depth at 7 wavelengths Contact: Ellsworth Dutton (ellsworth.g.dutton@noaa.gov, phone: (303)497-6660) Anne Jefferson (anne.jefferson@noaa.gov, phone: (303)497-6493) NOAA Climate Monitoring and Diagnostics Laboratory (CMDL) 325 Broadway R/CMDL 1 Boulder, CO 80305, USA Fax: (303)497-5590 Web: http://www.cmdl.noaa.gov/star/index.html Data Set Description: Continuous daytime measurements of direct and downwelling diffuse solar irradiances and spectral optical depth were made at Kosan during ACE-Asia by CMDL. The measurements were made at the top of a 40 m tower at 33.292 N,126.162 E during observational phase of ACE-Asia and were placed on a lower, 3 m tower for the remainder of the deployment, through January 2002. The broadband solar irradiances cover a wavelength range from 0.285 to 4.0 um. The solar irradiances were made in accordance specifications of the World Climate Research Program's Baseline Surface Radiation Network (BSRN), Ohmura et al., 1997. The calibrations of the instruments are traceable to the World Radiation Reference (WRR) standard and are accurate to within about 10 W/m2 for the one-minute averages recorded from the 1 Hz sampling rate. Some further improvement of accuracy is obtained by longer averaging times. Spectral optical depth was computed using standard Langley sunphotometers calibration methods, Dutton et al. 1992 and references therein. Aerosol optical depths are determined for time periods when the direct solar beam was determined to be free of cloud influences by subtracting Rayleigh scattering and known and estimated gaseous attenuators from the observed total optical depths. The aerosol optical depths are believed to be accurate to within 0.015 optical depth units. References: Dutton, E.G., P. Reddy, S. Ryan, and J.J. DeLuisi, 1994. Features and effects of optical depth observed at Mauna Loa, Hawaii: 1982-1992. J. Geophys. Res. 99, 8295-8306. Ohmura, A., et al., 1997: Baseline Surface Radiation Network (BSRN)/WCRP), a new precision radiometry for climate research. Bull. Amer. Meteoro. Soc. 79, 2115- 2136.