Physics of Ocean Color Remote Sensing
A typical water color remote sensing situation is depicted in Fig. 1, which shows the satellite’s radiometer aiming toward a spot on the sea surface (marked PIXEL), hence measuring the radiance LT(θ,Ø) emerging from the Earth’s atmosphere. The goal of this measurement is to determine the concentration of the various constituents of the water (e.g., phytoplankton, total suspended material, yellow substances, etc.). The radiance LT(θ,Ø) consists of photons which have been multiply scattered from the atmosphere, ocean, and sea surface, and thus depends in a complex manner on the optical properties of the atmosphere (and their distribution with altitude) and on the optical properties of the ocean (and their distribution with depth). Through a series of Monte Carlo simulations (Gordon, 1976) of radiative transfer in an ocean-atmosphere system characterized by realistic and vertical distributions of all pertinent optical properties in the atmosphere, and a representative set of optical properties for the ocean (assumed homogeneous), three simplifying facts emerge.
KeywordsOcean Color Aerosol Optical Thickness Aerosol Scattering Diffuse Transmittance Beam Attenuation Coefficient
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