Ocean surface films measured by interferential microwave probe

Summary Measurements on sea surface films were conducted during five separate experimental periods in the following marine areas: the Sicilian Channel, the Gulf of Maine (spring and fall periods), Bermuda, and the Pacific Ocean West of Southern California. The measurements consisted in surface elevation sampling using an interferential microwave probe with frequency spectra evaluation. Wave spectra were performed for both clean and film-covered sea surface conditions to determine the wave attenuation ratio within the 2–20 Hz spectral range. The method is able to detect, chart and characterize sea surface films. Theoretical analyses of the results yield several viscoelastic film parameters: the modulus of elasticity, the relaxation frequency and the maximum of the damping ratio as a function of wave frequency. The analysed data are interpreted to infer film weathering effects, surface concentration of film-forming constituents, and compactness of the organic sea surface film.