RADIANCE-IRRADIANCE INVERSION ALGORITHM FOR ESTIMATING THE ABSORPTIONAND BACKSCATTERING COEFFICIENTS OF NATURAL-WATERS - VERTICALLY STRATIFIED WATER BODIES

A full multiple-scattering algorithm for inverting profiles of the upw elling and down welling irradiances to yield profiles of the absorptio n and backscattering coefficients in a vertically stratified water bod y is described and tested with simulated data. The algorithm does not require knowledge of the scattering phase function of the medium. The results are better the closer the phase function assumed in the retrie vals is to the true phase function, although excellent retrievals of t he absorption coefficient can still be obtained with an inaccurate pha se function. Simulations show that the algorithm is capable of determi ning the vertical structure of a stratified water body and usually pro vides the absorption coefficient profile with an error less than or si milar to 2% and the backscattering coefficient profile with an error l ess than or similar to 10%, as long as the spacing between pseudodata samples is sufficiently small that the necessary derivatives of the ir radiances can be accurately computed. The performance is only slightly degraded when the upwelling radiance (nadir viewing) is substituted f or the upwelling irradiance. (C) 1998 Optical Society of America.