Acoustic scattering affected by monomolecular films spread over a wind-driven water surface

A spectrum of amplitude fluctuations of the ultrasonic signal scattered from a wind-created water surface covered with an oil substance monolayer of well-defined viscoelastic properties was examined under laboratory conditions. The presence of an oil film causes a shift of the peak frequency towards higher frequencies and increases the fall-off on the high-frequency band of the spectrum if compared to clean surface scattering. The effect turned out to be unequivocally related to rheological parameters of the given monolayer film.