Aspect dependence of the polarimetric characteristics of sea clutter: I. Variation with elevation angle

The polarisation dependence of radar scattering from the sea at low to moderate angles of incidence has been studied extensively and has shown Bragg scatter to be the dominant mechanism for these geometries. At high angles of incidence the polarimetric scattering behaviour is rather more complicated, with numerous mechanisms active. The transition region where the characteristics of the radar scattering from the sea changes, is not so well understood, due partly to the scarcity of experimental data from the open sea. Wave tank measurements have addressed some aspects, but it is not always easy to extrapolate these results to the natural environment. In this paper we examine the transition from Bragg scattering at low incidence angles to the more complicated scattering which occurs at high incidence angles by examining the changes that occur to the distribution of points in the partitioned H-alphamacr space.