Ka-Band Radar Cross-Section of Breaking Wind Waves

The effective normalized radar cross section (NRCS) of breaking waves, σwb, is empirically derived based on joint synchronized Ka-band and video records the sea surface from a research tower. σwb key parameter that, along with breaker footprint fraction, Q, defines contribution non-polarized backscattering, NP =σwbQ, to total NRCS. Combined right representation regular Bragg specular backscattering components, component fundamental model interpret measurements. As first step, difference between NRCS values for non-breaking conditions scaled optically-observed Q compared geometric optics backscattering. Optically-derived might not be optimal represent effect waves Alternatively, we rely crest length that firmly detected by technique estimated decay (inverse wavelength) scale in direction wave propagation. A simplified then proposed using approach. This semi-analytical parameterizes along-wave reported roughness spectra, obtained laboratory experiments mechanically-generated breakers. These empirical estimates agree satisfactorily observations.