Radar investigations of breaking water waves at low grazing angles with simultaneous high-speed optical imagery

Radar scattering experiments were carried out at the wavetank facility at the University of Maryland-College Park. Spilling and plunging breakers were generated by means of a chirped wave packet, and were then imaged with a high-speed camera. Simultaneously, the radar backscatter generated by the breakers at a nominal grazing angle of 12 degrees was measured by an ultrawideband, dual-polarized, X-band radar with a range resolution of approximately 4 cm. This experimental setup also included a moving instrument carriage that allowed the sensors to follow the breakers throughout their entire evolution. In conjunction with numerical simulations, these experiments can guide the development of realistic scattering models by identifying the important wave features and the corresponding scattering mechanisms.