Theoretical and experimental studies of sea surface current and wind waves spectra estimation using microwave Doppler marine radars

The paper considers the results of a promising method for remote determination of parameters of dynamic processes in the ocean – coherent ocean radar sensing. This work proposes a methodology for determining the speed and direction of the sea surface current and wind waves spectrum by measurements of X-band Doppler radar. Based on the Doppler Effect, it is possible to measure the orbital velocities of wind waves on the sea surface, the velocities of breaking waves, the velocities of the sea surface current and the speed parameters of other oceanic dynamic processes. Using the basic expressions of the wave theory of free waves on water, it is possible to restore the heights of wind waves without additional calibration. Theoretical numerical simulation of the Doppler velocity of the Bragg waves in the field of wind waves and currents were carried out. The simulation used a two-scale model of microwave scattering on an wavy water surface, taking into account the shading of the sea surface by wave crests. A correlation analysis of the surface current, calculated through hydro meteorological parameters and Doppler radar panoramas, showed a maximum correlation coefficient for a velocity value is about 0.88 with a root mean square error of 8 cm/s, and for a direction is about 0.98 with a root mean square error of 14 degrees. The work shows the possibility to recover wind wave spectra from the data on the Doppler shift of microwave radio waves. Features that are not described by the two-scale model are found and discuss.