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.