Microwave radar probing of a rough water surface: validation of retrieval algorithms using flight experiment data

摘要

We studied the microwave backscattering of a rough water surface during a flight above the Gorky water storage basin. A microwave Doppler radar with a knife-like beam (1-16°) was installed on a helicopter and oriented vertically downwards. Analysis of the experimental data confirms that the reflected power and the width of the Doppler spectrum depend on the direction of wave propagation. 'Antenna' and 'angular' algorithms were used to obtain the variance of the slopes. These algorithms enabled us to determine the slope variance from a moving carrier, without limitations placed on the flight's height. We developed two new algorithms to determine the correlation coefficients of the vertical component of the orbital velocity and water surface slopes as well as the variance of orbital velocities using the width of the Doppler spectrum. We used the results obtained from varying the input parameters of the algorithm to minimize the retrieval error of the correlation coefficient. Comparisons with parameters derived from modelled wave spectra indicate the effectiveness of the retrieval algorithms. We also demonstrate the possibility of extracting estimates of the average phase velocity, the average wavelength and the significant wave height of sea waves.