Raman scattering and in-water ocean optical properties.

Inelastic (transpectral) scattering may contribute significantly to the in-waterlightfield. Major mechanisms for inelastic scattering include Raman scattering, which we show is important in clear ocean waters, and fluorescence from a variety of sources, which may be important in more turbid waters. We have determined the Raman cross section for liquid water, 8.2 x 10(-30) (cm(2) sr(-1) molecule(-1)), which is in agreement with the lower range of published values. The influence of Raman scattering, based on predictions of a modified two-stream model, is in agreement with measured values of spectral reflectance R(lambda,z) and the spectral diffuse attenuation coefficient for irradiance K(lambda,z). Inelastic scattering has important ramifications for several aspects of marine biooptics including the determination of in-water spectral absorption, the estimation of clear water ocean optical properties, and possibly various aspects of algal photobiology.