APPARENT OPTICAL-PROPERTIES OF OCEANIC WATER - DEPENDENCE ON THE MOLECULAR-SCATTERING CONTRIBUTION

The relationships between the apparent optical properties (AOP's) and the inherent optical properties (IOP's) of oceanic water bodies have b een reinvestigated by solution of the radiative transfer equation. Thi s reexamination deals specifically with oceanic case 1 waters (those f or which phytoplankton and their associated particles or substances co ntrol their inherent optical properties). In such waters, when the chl orophyll content is low enough tin most of the entire ocean), the infl uence of molecular scattering by water molecules is not negligible, le ading to a gradual change in the shape of the phase function. The effe ct of this change on the AOP's is analyzed. The effect of the existenc e of diffuse sky radiation in addition to the direct solar radiation o n AOP-IOP relationships is also examined. Practical parameterizations are proposed to predict in case 1 waters, and at various depths, the v ertical attenuation coefficient for downward irradiance (K-d) as a fun ction of the IOP's and solar angle. These parameterizations are valid for the spectral domain where inelastic scattering does not significan tly occur (wavelengths below 590 nm). (C) 1998 Optical Society of Amer ica.