Depolarized radar return for breaking wave measurement and hurricane wind retrieval

O. M. Phillips (1988) elucidated the double structure of sea surface scatterers for radar scattering from the ocean surface. The wind generates a distribution of small slope waves and sporadic steep breaking events. The signature of double structure is in the wind speed dependence of radar returns: linear for scattering from gentle waves and cubic for breaking contribution. The composite Bragg (CB) theory successfully describes the former. The breaking contribution remains elusive. Here we show that the depolarized (de-pol) radar return exhibits the typical double structure, its wind speed dependence increases with wind speed from linear to cubic. The enhanced sensitivity of de-pol returns in high winds is ideal for hurricane wind retrieval. The strong breaking connection offers an opportunity to measure wave breaking and associated energy dissipation and area of foam coverage from space, their quantification is important in air-sea interaction and electromagnetic and electro-optical remote sensing. Citation: Hwang, P. A., B. Zhang, and W. Perrie (2010), Depolarized radar return for breaking wave measurement and hurricane wind retrieval, Geophys. Res. Lett., 37, L01604, doi: 10.1029/2009GL041780.