The scattering of sunlight in the atmosphere-ocean system : a study using Monte Carlo techniques

Abstract

Separate Monte Carlo programs are developed to evaluate the distribution of scattered light in the earth's atmosphere-ocean system. In one case the radiance, the degree and direction of polarization, and the ellipticity are calculated, using a flat-ocean model, for the radiation at various optical depths in the atmosphere and the ocean. In the other case radiances are calculated for a model which includes ocean waves. In each case absorption and all orders of multiple scattering by hydrosols and aerosols as well as by Rayleigh scattering centers are taken into account. Complete single-scattering phase matrices are used for the calculation of the polarization quantities, which are given as functions of ocean turbidity, the solar zenith angle, and the wavelength of the radiation. Mie theory is used to compute the phase matrices for the aerosols and hydrosols, which are assumed to have appropriate particle-size distributions. Reflection and refraction at the air-water interface are fully considered. The model for ocean waves is based on the Cox-Munk distribution, and radiance calculations performed through the use of this model are presented for various cases of wind speed (sea roughness), solar zenith angle, and detector location, and for two wavelengths. Flux transmission into the ocean under various conditions is also considered. Possibilities for remote sensing applications axe pointed out. A separate set of calculations (not using a Monte Carlo procedure) is carried out to study in detail the glitter pattern produced by sunlight on a wind-ruffled sea; these calculations are presented as contour plots of the intensity and the degree of polarization of the glitter pattern.