Can geometric optics fully describe radar images of the sea surface at grazing incidence?

It is possible to estimate the significant wave height of the ocean surface using shadowing statistics computed from grazing incidence radar imagery. The theoretical basis for this estimation is a geometric optics view of a gaussian surface. In practice it is necessary to apply an empirical correction based on the intensity of the radar backscatter in order to produce a wide range of verifiable wave heights. To explore the reasons for this correction, we have conducted a one-dimensional Monte-Carlo simulation of the sea surface at a wide range of significant wave heights, and have observed it with a ray trace program from several source heights and configurations. We conclude that, although the finite amplitude effects simulated in this experiment partially explain the results observed at sea, some electromagnetic interaction unaccounted for in geometric optics must also be responsible for the result. We suggest that increased local incidence angle is a possible source of the difference between observations and our simulation.