Imaging of azimuth ocean waves by a conventional microwave radar

Summary form only given. Images of ocean waves near coastal areas were obtained by means of a conventional radar. Refraction patterns were readily discernible, and the angle of the crests approaching the beach could be estimated in order to provide useful information to a coastal monitoring program concerned with erosion problems, among others. Attention was drawn to the fact that azimuth traveling waves were observed in those pictures under various circumstances. This gave rise to questions about the range selective behavior of the tilt and hydrodynamic interaction modulation transfer functions, which are the relevant functions for the detection of ocean waves by real aperture microwave radar. Short wave directionality was incorporated into a simple computer scheme to estimate the tilt and hydrodynamic interaction transfer functions. The radar image spectrum was simulated using the ocean wave spectrum and the modeled transfer functions. From the results, the imaging of neat azimuth traveling waves can be explained. It is concluded that the effect of short-wave directionality is to enhance the azimuth wave detectability under certain local wind conditions. The exact shape of the short-wave spectrum was not determined. The results obtained show that it an essential piece of information for adequate use of remote-sensing techniques to measure ocean waves.