Phase Distribution of Small-Scale Ocean Surface Roughness*

Remote sensing is becoming an important tool for oceanographic research. As the resolution of remote sensors is becoming comparable to the wavelength of dominant ocean surface waves, the usual assumption of homogeneous surface roughness is no longer adequate. In this paper, laboratory data of surface wave displacement and small-scale surface roughness (wavelength 0.004–0.10 m) measured by a scanning slope sensor are analyzed. The results show that higher intensity of surface roughness occurs at the upwind quadrant of the wave crests of background waves. Over a wide wind speed range, the maximum surface roughness is located close to the maximum of surface velocity divergence.