Evaluation of Marine Wave Radar (Part II)

Abstract

The importance of the knowledge of ocean waves parameters for the naval and ocean engineering field is not questionable, and the limitations of the available methods to obtain this valuable information is the leading motivation to the search of better approaches and improved analysis methods. The use of conventional marine radar PPI images allows the estimation of wave parameters on a real-time basis, using both space and time information about the evolution of the ocean surface waves. In Part I, the two-dimensional (spatial information) spectral analysis of one radar PPI image was performed, and the limitations of this approach could be evaluated using radar images numerically generated. To overcome those limitations the wave number-frequency spectrum is calculated from a set of radar images through a three dimensional FFT. The understanding of the components of this spectrum and the comparison with the expected dispersion shell allows the filtering of noise and correction of aliased frequencies. In this paper, simulated radar images generated as described in Part I and experimental data are used to evaluate the analysis method. The significant wave height was recovered using a new approach based on the shadow ratio present on the radar image.