Observing Marine Pollution with Synthetic Aperture Radar

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On the vibration modes of the air-water interface in presence of surface films

A numerical method is described which allows one to obtain the solutions of the linearized Navier-Stokes equation for the case of wave motion at the air-water interface in the presence of both soluble and insoluble films. The results are shown, and we discuss evidence of two vibration modes, i.e. transversal and longitudinal waves. Their behaviour appears to be closely linked, especially in the case of insoluble films

A metric wave radio-acoustic tropospheric sounder

A metric wavelength version of the radio-acoustic sounding system (RASS) at Trino Vercellese, near Turin, Italy, is presented. Evidence is shown of satisfactory soundings in conditions of calm or light winds

Ocean surface films measured by interferential microwave probe

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

Small scale properties of the radar backscatter from the sea surface at off nadir angles

Analyses coherent radar backscatter data from the sea surface at C-band and VV polarization, sampled at 300 Hz. The aim is to understand their usefulness in the investigation of the sea surface properties. The variability of the backscatter intensity Ibk at frequencies close to the Bragg frequency suggested a Bragg-like mechanism in the formation of the radar backscatter from patches of Bragg waves randomly distributed in the radar footprint. This led us to consider that both I bk and the associated Doppler frequency fd have to be computed over time intervals of O(0.1) s, the periodicity of the Bragg waves at C-band and 45 degree of incidence. Shorter time intervals would produce unrealistic estimates. This sets the lowest limit of data sampling for further researc