The multisensory approach to hydrophysical measurements of the ocean surface layer

Abstract

The present paper is devoted to the development of a multisensory approach to hydrophysical measurements of the ocean surface layer. The combination of coherent acoustic sounding, coherent radar sounding, and optical stereo photography is considered. Each of the methods separately has several advantages, but it is not free from disadvantages. Coherent acoustic sounding, described by resonant scattering, has a large observation area but has a poor spatial resolution. Coherent radar sensing, also described by resonant scattering, has a smaller observation area but a higher spatial resolution. Both methods allow us to recover the velocity characteristics of scattering associated with the velocities of resonant scatterers. Using the relationship between sea surface elevations and orbital wave velocities, it is possible to determine the spatial spectra of wind waves in a wide range of wind wavelengths up to several meters. To determine the characteristics of shorter-scale wind waves, it is proposed to use data from optical stereo photography. As a calibration for the optical system, information on the elevation of the sea surface obtained from coherent acoustic and radar sounding data can be used. Thus, the spatial spectrum of wind waves can be reconstructed in the range of energy-carrying to gravitational-capillary waves. In addition to the spectral characteristics of waves, it is possible to determine the velocity of the near-surface flow by measuring the Doppler shift of acoustic and radar signals. High-resolution data obtained from stereo photography of the sea surface allow clarifying the relationship between the velocities of acoustic and radar scatterers and hydrometeorological parameters.