Directional spectra of the sea surface using marine radar

A horizontally polarized X-band (3 cm) ship's navigation radar was deployed aboard the research vessel CSS Hudson as part of the ERS-1 Calibration/Validation Experiment. Series of marine images of the sea surface were collected during the experimental cruise between Nov. 10-25 1991 on the Grand Banks of Newfoundland.;The azimuthal variation of backscattered power was investigated. An azimuthal variation in the derived image spectrum was found to arise from azimuthal variations in both backscattered power and the spatial modulation of the images induced by wave shadowing. The effects of both of these azimuthal variations must be removed in the production of directionally unbiased radar image spectra.;The image series were processed into directional image spectra using a three dimensional Fourier transform technique. These spectra were compared to wave and image spectra from a directional wave buoy and the ERS-1 satellite based synthetic aperture radar.