Wave-Induced Light-Field Fluctuations in the Sea

Irradiance fluctuations in the natural underwater light field close to the sea surface have an amplitude that is of the same order of magnitude as the mean irradiance. A principal source of these fluctuations, differential refraction by surface waves, is examined in this paper, and some experimental data obtained at an experimental site in the Bight of Abaco, Bahamas, are presented. A first-order single-ray theory is developed and the predictions of this theory are compared with the data. The theory identifies five refractive effects, the most important of which is the focusing and defocusing of light beams by fluctuations of surface curvature.