Possibilities of identification of oil films using radar probing of the sea surface

A brief review of experiments on damping of short wind waves due to surfactant (monomolecular) and oil films carried out at the Institute of Applied Physics RAS using radar and optical methods is given. The damping degree of wind waves (spectral contrast) in film slicks is analyzed in a wide (decimeter-centimetre-scale) wavelength range of wind waves at different wind speeds and physical characteristics of films. A simple local balance model of the wind wave spectrum is developed to describe the film effect on short wind waves. Differencies in the spectral contrasts for film slicks and for some ldquolook-alikesrdquo, in particular, for wind depression areas (WDA) are revealed: the spectral contrast for film slicks increases with surface wave number, while for WDA the contrast is practically constant for decimeter-centimeter-scale wind waves. The specific behaviour of the spectral contrast can be used as a slick ldquospectral signrdquo.