A new UV submersible spectroradiometer has been employed to determine the diffuse attenuation coefficient for irradiance in the clearest natural waters Kw(\lambda) with emphasis on the spectral region from 300 to 400 nm. Kw(\lambda) can be related to the inherent optical properties of pure water in particular the total absorption coefficient aw(\lambda) and the molecular scattering coefficient bm(\lambda), by means of equations derived from radiative transfer theory. The authors present an analysis showing that limiting values of Kw(\lambda) can be estimated from aw(\lambda) and vice versa. Published aw(\lambda) dat, which show discrepancies much larger than their estimated accuracies, are briefly reviewed and then compared, via the authors' analysis, with Kw(\lambda) data the authors' own new and previously published data as well as relevant data of others). This comparative analysis and new data allow a consistent and accurate set of optical properties for the clearest natural waters and for pure fresh water and saltwater to be estimated from 300 to 800 nm.

R. C. Smith, K. S. Baker, "Optical properties of the clearest natural waters (200-800 nm)," Appl. Opt.,20, 177-184 (1981).