Estimation and removal of multiple scattering contributions to HF surface wave radar echoes

Existing techniques for remote sensing of ocean surface conditions by HFSWR are predicated on the assumption that the Doppler spectrum recorded at a given time delay and direction of arrival can be associated with the ground range and bearing corresponding to great circle propagation over a smooth surface. In this paper we investigate the consequences of the spatio-temporal modulation accumulated by the radar signal during its transit across the intervening rough ocean surface. Specifically, we explore the dependence of the measured spectrum on the apparent range, and examine factors which may be exploited to develop an inversion scheme for multiply-scattered signals.