An alternative method for surface current extraction from X-band marine radar images

In this paper, a novel current inversion algorithm from X-band marine radar images is proposed. The routine begins with a 3D-FFT of the radar image sequence, followed by the extraction of the dispersion shell from the 3-D image spectrum. After a polar coordinate transformation, the "polar current shell" is then analyzed to retrieve current information such as the speed and direction of encounter. Particularly, a Grubbs\´ test is conducted to remove outliers along each radial direction, and a robust sinusoidal curve fitting is applied to the data points along each circumferential direction. For validation, the algorithm is tested against simulated radar PPI images. The results indicate that the proposed procedure, unlike most existing current inversion schemes, is not susceptible to high current speeds and has no direction restriction. Meanwhile, the relatively low computational cost makes it an excellent choice in practical marine applications.