Ocean Inherent Optical Property Estimation from Irradiances
WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING
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A method is evaluated for estimating the absorption coefficient a and the backscattering coefficient betasub beta from measurements of the upward and downward irradiances Epsilon sub muz and Epsilon sub dz. With this method, the reflectance ratio Rz and the downward diffuse attenuation coefficient Kappa sub dz obtained from Epsilon sub muz and Epsilon sub dz are used to estimate the inherent optical properties Rsub infinity and Kappa sub infinity that are the asymptotic values of Rsub infinity and Kappa sub infinity, respectively. For an assumed scattering phase function Beta, there are unique correlations between the values of Rsub infinity and Kappainfinity and those of alpha and betasub beta that can be derived from the radiative transfer equation. Good estimates of alpha and the Gordon parameter G betasub betaalpha beta sub beta can be obtained from Rinfinity and Kappasub infinity if the true scattering phase function is not greatly different from the assumed function. The method works best in deep, homogeneous waters, but can be applied to some cases of stratified waters. To improve performance in shallow waters where bottom effects are important, the deep- and shallowmeasurement reflectance models also are developed.
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