Second-Order Correction to the HF Radar Cross-Section of the Ocean Surface at Electromagnetically-High Sea States

An extension to the correction theory for the electric field and radar cross-section of the ocean surface under electromagnetically-high sea states is presented, accounting for the impact of second-order hydrodynamic interaction of waves on the total radar cross-section of the ocean surface in this case. An expression for the second-order correction factor to the radar cross-section is given, with an analysis of the impact of the presented term on the total radar cross-section of the ocean surface. It is shown that the second-order hydrodynamic correction term introduces energy to spectral regions outside the Bragg peaks, which can increase the integral over the second-order region at absolute frequencies greater than the dominant Bragg peak by up to 30%; this increase will likely affect the estimation of significant wave heights at electromagnetically-high sea states.