Ship wakes and their radar images

Remote observations of a surface ship wake using synthetic aperture radar (SAR) show distinct features such as a dark trailing centerline region, bright V-images aligned at some angle to the ship's path, and, sometimes, either the transverse or the diverging waves of the Kelvin-wave pattern. The dark region of relatively low radar backscatter is usually associated with a region that is relatively lacking in short wave components, whereas the bright line feature suggests a region of enhanced radar return within the apparent angular confines of the ship's usual Kelvin-wave pattern. This review provides a survey of remotely sensed wake images, the systems that have collected these images, and an overview of the theory of Kelvin wakes-a primary source of the phenomena that cause the dark centerline and bright V-images-with example predictions. The review concludes with a survey of the phenomena that cause the dark centerline returns and some example predictions of the radar reflectivity across these dark centerline returns.