OCEAN-COLOR MODEL INCORPORATING TRANSSPECTRAL PROCESSES

Ocean color is determined by spectral variations in reflectance at the sea surface, which in turn result from both elastic and inelastic pro cesses. We extend an elastic-scattering model of sea surface reflectan ce to deal with Raman scattering, which is an inelastic process. The a nalytic solutions are derived for a vertically homogeneous and optical ly deep water column. The model presented here is based on the quasi-s ingle-scattering approximation of Gordon [Appl. Opt. 12, 2803 (1973)] and is an extension of the model of Sathyendranath and Platt [Appl. Op t. 36, 2620 (1997)]. The Raman-scattering model includes a first-order Raman-scattering term and four second-order terms. Two of the second- order terms result from a combination of an elastic and a Raman-scatte ring event, whereas the other two second-order terms result from two R aman-scattering events. Ne show that the contribution to reflectance f rom these last two terms is typically of the order of 1% of the first- order Raman-scattering term. Therefore these terms and higher-order te rms can be neglected for most applications. issues related to the impl ementation of the model are discussed, with special reference to remot e-sensing applications. Results from the analytic model are compared w ith Monte Carlo simulations of reflectance at the sea surface. (C) 199 8 Optical Society of America.