Extraction of Sea-State Parameters with an X-Band Radar

摘要

Ocean wave spectrum and surface currents can be de- termined from a series of spatial wave images recorded by an X-band marine radar. In the absence of a surface current, the three-dimensional spectral energy found by using the series of images will be confined to a trajectory defined by the still water dispersion relationship. The presence of a surface current will make the three-dimensional spectral energy show a corresponding Doppler shift which may determine the current using the least squares method and obtain the directional wave spectrum. On the basis of conventional wave spectrum and directional function, the paper emulates a series of X-band radar images considering shadowing modulation and simulates numerically the three- dimensional image spectrum both with and without a surface cur- rent, calculates the current velocity by virtue of the Doppler shift, and obtains the two-dimensional image spectrum. Finally the pa- per analyzes measured wave level elevation—a function of time t to obtain one-dimensional image spectrum, and the data comes from an X-band radar in McMaster University.