Airborne optical measurements of wind-wave spectral perturbations induced by ocean internal waves

During the 1992 joint US/Russia Internal Wave Remote Sensing Experiment the large-scale structure of the ocean surface was investigated using a high resolution optical air photocamera. Data were recorded on photographic film, and then two-dimensional Fourier spectra of optical images were computed digitally. It was found a strong changing of the spectrum of wind waves due to the influence of ocean internal waves. In particular, wavenumber spectrum of optical images is unstable in the field of internal waves. Multimode structure of the spectra of wind waves is usually very much more pronounced in the case of nonlinear internal waves. The observed picture could be interpreted as a result of the multiwave nonlinear interaction between surface gravity waves and internal waves