On the detection of organic films from variations of sea surface radiance

Abstract

An optical model of imaging of film slicks on the sea surface in scattered sky light is discussed. Experimental verification of the model is presented based on measurements of the sky radiance profiles and of wave damping in the spectrum of short wind waves due to organic films. The measurements were carried out in field experiments with artificial slicks using optical spectrum analysers and photometers at different sea states and geometry of observations. Simultaneously measured wavenumber spectra, the spectrum contrasts in slicks, and the sky light angular distributions are presented. Using a simple model of wind wave damping due to films and the optical model of wave imaging, variations of the sea surface radiance in slicks are calculated and are shown to be in good agreement with experiment. Possibilities of slick detection by simple optical instruments under different observational conditions are discussed.