Dual-polarized, coherent microwave backscatter from rough water surfaces at low grazing angles

We show that at low grazing angles, breaking wave effects are very important in HH polarized microwave backscatter from the ocean but less so at VV polarized backscatter. When the ocean surface is disturbed only by wind, breaking wave effects in VV backscatter are much smaller than Bragg scattering, even at low grazing angles. For HH polarization, on the other hand, breaking wave effects are very important at low grazing angles. In the presence of surface current gradients set up by internal waves, HH cross sections can exceed those at VV by as much as 10 dB near internal wave crests, indicating enhanced breaking wave effects that cannot be described as specular. Breaking effects are nearly as strong as Bragg effects in VV backscatter under these conditions. Spectral comparisons confirm these conclusions.