Albedos and Glitter Patterns of a Wind-Roughened Sea Surface

Abstract

Abstract The downward albedo (irradiance reflectance) r− and the upward albedo r+ of a random air–water surface, formed by capillary waves, are computed as a function of lighting conditions and wind speed by Monte Carlo means for incident unpolarized radiant flux. The possibility of multiple scattering of light rays and of ray-shielding of waves by other waves is included in the calculations. The effects on r± of multiple scattering and wave shielding are found to be important for higher speeds (≳10 m s−1) and nearly horizontal light ray angles of incidence (≳70°). The Monte Carlo procedure is used to generate reflected and transmitted glitter patterns as functions of wind speed and sun position. These results are used to check the procedure's patterns against observed patterns. A simple analytic first-order model of glitter patterns and irradiance reflectance, which assumes a binormal distribution of water facet slopes, is tested against the relatively exact Monte Carlo results. Regions are defined in wi...