Radiative Transfer in the Earth's Atmosphere-ocean System: II. Radiance in the Atmosphere and Ocean

Abstract

The upward and downward radiance is calculated for a realistic model of the atmosphere-ocean system by a Monte Carlo method. All known processes are taken into account which affect the solar photons, including scattering and absorption by atmospheric and oceanic molecules, and by aerosols and hydrosols, as well as reflection and refraction at the ocean surface. The scattering angles are chosen from distributions calculated from Mie theory for the aerosols and hydrosols and thus take account of the strong forward-scattering peak. Typical radiance values are presented at six wavelengths from 0.40 to 0.65 μ, for three different solar angles, and for three different models of the ocean with various amounts of turbidity. The minimum value of the upward radiance just above the ocean surface as a function of the nadir angle of observation increases 640% from the turbid to the clear ocean model. Even at the top of the atmosphere the increase is 40%. Thus, detectors in either airplanes or satellites should be able to obtain important information about the turbidity of the ocean. Other features shown in the results include the development with depth of the downward radiance both within and without the allowed cone into which radiation may enter the ocean from the sun and sky, the development of the asymptotic form for the downward radiance with depth, and the dependence of the radiance at various depths upon the turbidity of the ocean as well as the wavelength of the radiation.