Retrieving of Waves Parameters and Waves Direction Using the Doppler Spectrum of Reflected Radiation

Information on sea waves is used to solve a wide range of fundamental and applied problems, from climate change monitoring to ensure the safety of navigation and life in coastal areas. The most accessible is information on the sea surface heights variance since the energy of sea waves is related to this parameter. Height variance is measured using sea buoys (of which there are more than 1500 in the World Ocean) and space-based radar altimeters, which provide a continuous series of measurements over the entire World Ocean for over 25 years. The intensity of heat and gas exchange between the atmosphere and the ocean largely depends on the roughness of the sea surface, and the sea wave slope variance can be used to estimate the degree of roughness. However, this parameter is not currently measured on a regular basis. This work is devoted to the development of a new method for retrieving key parameters of the sea surface (including slope variance), as well as the direction of wave propagation both in the World Ocean and in inland water bodies. To solve the inverse problem, a measurement scheme is proposed with three underwater Doppler sonars directed at different azimuthal angles. The advantage of the obtained method for solving the inverse problem is the presence in the input parameters only of the width and shift of the Doppler spectrum of the reflected radiation, and the absence in the input parameters of the backscattering cross-section, which requires a complex calibration procedure. In this measurement scheme, it is also possible to determine the direction of wave propagation from the shift of the Doppler shift of 3 antennas.