IMAGING MEASUREMENT OF WHITECAPS AT SEA OBSERVATION TOWER

摘要

Whitecap coverage was estimated from imaging measurements at a sea observation tower. High-resolution images of whitecaps were taken using a digital camera system located at 14 m above the mean sea level, and they were stored automatically in steps of 1 s. The present results indicate that the 1/3 power of whitecap coverage increases linearly with increasing the wind speed at an elevation of 10 m, and that whitecapping is influenced significantly by the near-water air stability and the state of development of surface waves. Whitecaps are produced most activity under the condition of pure windsea, and they tend to be suppressed by the presence of swell. It is difficult to find the dependence of whitecap coverage on the deflection angle between propagating directions of wind waves and swell.