Polarimetric observations of wave breaking induced by ship wakes

Describes two experiments conducted using the DSTO mobile high resolution radar facility to observe wave breaking events induced by ship wakes. In the first experiment high resolution polarimetric range profiles of the wake produced by a displacement hull vessel were recorded at X and Ku band frequencies. Periodic transient enhancements were observed, generated by wave breaking events precipitated by the superposition of the dominant wake components with the crests of the incoming swell. In order to identify the induced wave breaking events unambiguously, the measurements were carried out for ship headings directly into and directly opposed to the prevailing waves. Clear confirmation of the proposed mechanism was thus demonstrated. The second experiment employed a planing hull vessel. Because of the high speed of this ship, the measurement geometry was changed to set one of the diverging wake arms perpendicular to the radar beam. High resolution polarimetric range profiles were then recorded at X and Ku band frequencies.