Ocean sun glint albedo estimation from geostationary satellite data

Abstract

Specular reflection off the ocean surface has been used to derive ocean wave heights and surface wind speeds, but the effect that waves have on ocean surface reflection of incident solar radiation is not fully understood. This study focussed on measuring how sun glint affects the Earth's radiation budget, by including the previously ignored specularly reflecting region. Measurements collected by the GOES-10 geostationary satellite were used to produce an effective sun glint albedo to characterize the accuracy of omitting the glint region from the radiation budget. Estimations were made using the Cox/Munk statistical distribution model. These results varied slightly as a function of wind speed where a 6 m/s surface wind speed produced an effective clear sky sun glint albedo of 1.9%. This value was less than the satellite measured value of 2.2 ± 0.1% for measurements in the cloud free region. Estimates including clouds show a smaller glitter effect of 1.7 ± 0.1%. These values were then extrapolated to the full Earth value by including ocean fraction resulting in global values of 1.6 ± 0.1% and 1.2 ± 0.1% for clear sky and cloudy respectively.