Absorption coefficients of marine waters: expanding multiband information to hyperspectral data

For many oceanographic studies and applications, it is desirable to know the spectrum of the attenuation coefficient. For water of the vast ocean, an effective way to get information about this property is through satellite measurements of ocean color. Past and present satellite sensors designed for ocean-color measurements, however, can only provide data in a few spectral bands. A tool is needed to expand these multiband measurements to hyperspectral information. The major contributors to the attenuation coefficient are absorption and backscattering coefficients. The spectral backscattering coefficient can generally be well described with a couple of parameters, but not so for the spectral absorption coefficient. In this paper, based on available hyperspectral absorption data, spectral-transfer coefficients are developed to expand multiband absorption coefficients to hyperspectral (400-700 nm with a 10-nm step) absorption spectrum. The derived transfer coefficients are further applied to data from field measurements to test their performance, and it is found that modeled absorption matches measured absorption very well (∼5% error). These results indicate that when absorption and backscattering coefficients are available at multiple bands, a hyperspectral attenuation-coefficient spectrum can now be well constructed.