Airborne remote sensing of breaking waves

Airborne scanning laser ranging provides rapid measurements of the ocean wave topography. In addition to active ranging, the scanning optics can obtain passive measurements of the surface emissivity, yielding a digital image of the surface brightness. The brightness data contain information on the statistics and spatial distribution of whitecaps. Combining active measurements of the 3D surface topography and passive brightness data, the phase distribution of breaking events along a wave profile can be examined. From the phase distribution analysis, it is found that in deep water, the whitecap coverage in the windward phase is slightly higher than that in the leeward phase (51±17% vs. 49±14%), and more whitecaps are found on the crests than in the troughs (57±13% vs. 44±16%). Such quantitative information on wave breaking and whitecap coverage is important to remote sensing applications and air–sea interaction studies.