Ka-band radar backscattering from breaking waves: wave tank study

Stanislav A. Ermakov; Vladimir A. Dobrokhotov; Irina A. Sergievskaya; Ivan A. Kapustin; Alexander V. Kupaev

doi:10.1117/12.2574167

20 September 2020 Ka-band radar backscattering from breaking waves: wave tank study

Stanislav A. Ermakov, Vladimir A. Dobrokhotov, Irina A. Sergievskaya, Ivan A. Kapustin, Alexander V. Kupaev

Proceedings Volume 11529, Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2020; 115290S (2020) https://doi.org/10.1117/12.2574167
Event: SPIE Remote Sensing, 2020, Online Only

Conference Poster

Abstract

The role of wave breaking in microwave backscattering from the sea surface is a problem of great importance for development of theories and methods of the ocean remote sensing. Recently it has been shown that the microwave radar return is determined by both Bragg and non Bragg scattering components, and some evidences have been given that the latter is associated with wave breaking. However, our understanding of different mechanisms of the role of wave breaking on small-scale wind waves (ripples) and thus on the radar return is still insufficient. This paper presents results of laboratory experiments on the influence of wave breaking on Ka-band radar signals. An effect of the radar return suppression after wave breaking has been revealed and attributed with wind ripples suppression by breaking waves. The experiments were carried out in an oval wind wave tank where intense m/dm-scale surface wave trains were generated by a mechanical wave maker, in particular using a method of dispersive wave focusing. Wind waves were independently generated in the wave tank. A Ka-band radar was mounted at a height of about 1 m above the water level the incidence angle of microwave radiation was about 50 degrees. The experiments were performed both for a clean water surface and in the presence of an oleic acid monomolecular film. It has been obtained that the radar return before the wave train was determined by wind ripples, the radar Doppler spectrum was centered close to the Bragg wave frequencies. The radar signal intensity was strongly enhanced in a wide frequency range when the train was passing by the study area. After the intense wave train the radar return dropped and then slowly recovered to the initial level. We believe that the attenuation of radar backscattering after the wave train is due to suppression of wind ripples by turbulence and surfactants associated with wave breaking.

Citation Download Citation

Stanislav A. Ermakov, Vladimir A. Dobrokhotov, Irina A. Sergievskaya, Ivan A. Kapustin, and Alexander V. Kupaev "Ka-band radar backscattering from breaking waves: wave tank study", Proc. SPIE 11529, Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2020, 115290S (20 September 2020); https://doi.org/10.1117/12.2574167

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