Analysis of coherent radar sea clutter with combined wind driven sea and swell

Radar systems operating in a maritime environment need to be able to detect targets against a background of sea clutter returns. Hence it is important to understand the statistical behaviour of these returns in order to optimise a radar system detection algorithm. In this paper low and medium grazing angle radar sea clutter are analysed, to separate the effects of wind driven sea and swell in the Doppler spectrum. The offset gamma distribution is an effective model for the Doppler centroid and width distributions, as well as the asymmetric profile of the spectrum itself. The mean Doppler velocity is mostly due to the wind driven sea, with a contribution from the orbital velocity of the swell. A revised model is proposed for the mean Doppler shift as a function of grazing and azimuth angles.