Quantitative estimation of the underwater radiance distribution

Abstract

Within the Radiance in a Dynamic Ocean (RaDyO) program, we have created and deployed a high dynamic range camera that can resolve the full spherical radiance distribution at the ocean surface and at depth. We present here the first results from deployments of the camera in near-surface water in eutrophic, mesotropic, and oligotropic environments. The instrument resolves the dynamics and fine structure of both the downwelling and upwelling radiance distribution and its variation with depth in these optically diverse water types. The various irradiances (Ed, Eu, Eo, Eou, and Eod) are computed by integration. The distribution functions (e.g., the average cosines) are computed directly, as are the various diffuse attenuation coefficients. The fully specified radiance field therefore provides all the pertinent information to derive not only all of the apparent optical properties but, in principle, the inherent optical properties such as the absorption coefficient and the phase function as well. Comparison of the measured radiance field to independent measurements has shown very good agreement. Copyright 2011 by the American Geophysical Union.