OBSERVATIONS OF THE SPECTRAL DISTRIBUTION OF SOLAR IRRADIANCE AT THE GROUND DURING SUCCESS

During SUCCESS two independent and independently calibrated spectromet ers were deployed at a surface site to determine the spectrally resolv ed downwelling solar irradiance. Preliminary evidence shows that for c loud-free conditions there is general agreement between measurements a nd model derived irradiance, at least to within instrumental and model uncertainties of 5%, with greatest disagreement occurring in the 400 nm - 700 nm band. Cirrus effects are most prominent in the near-infrar ed bands beyond 1500 nm while the influence of very thin (subvisual) c irrus is evident in the scattered flux at the surface. Further remote sensing applications and the assessment of cloud absorption is conting ent upon measurements of the surface spectral albedo.