METHOD TO DERIVE OCEAN ABSORPTION-COEFFICIENTS FROM REMOTE-SENSING REFLECTANCE

A method to derive in-water absorption coefficients from total remote- sensing reflectance (ratio of the upwelling radiance to the downwellin g irradiance above the surface) analytically is presented. For measure ments made in the Gulf of Mexico and Monterey Bay, with concentrations of chlorophyll-a ranging from 0.07 to 50 mg/m(3), comparisons are mad e for the total absorption coefficients derived with the suggested met hod and those derived with diffuse attenuation coefficients. For these coastal to open-ocean waters, including regions of upwelling and the Loop Current, the results are as follows: at 440 nm the difference bet ween the two methods is 13.0% (r(2) = 0.96) for total absorption coeff icients ranging from 0.02 to 2.0 m(-1); at 488 nm the difference is 14 .5% (r(2) = 0.97); and at 550 nm the difference is 13.6% (r(2) = 0.96) . The results indicate that the method presented works very well for r etrieval of in-water absorption coefficients exclusively from remotely measured signals, and that this method has a wide range of potential applications in oceanic remote sensing.