The Pareto distribution for high grazing angle sea-clutter

Robust maritime surveillance with radar requires an accurate description of the backscatter from the sea. The probability distribution of the backscatter is commonly used to determine the threshold for separating targets from clutter. Analysis of data collected at high grazing angles, 15° and 45° by the Defence Science Technology Organisation (DSTO) Ingara fully polarimetric X-band radar has shown that the exponential power model is not sufficient to model the probability distribution of the radar backscatter. Recent studies have shown that the Pareto distribution is extremely useful as it both captures the high magnitude components of the sea-clutter and allows significantly simpler optimal and sub-optimal detectors. To further enhance the usefulness of this distribution, this paper presents a multi-look formulation which accounts for the thermal noise in the radar. The underlying shape is derived using both numerical integration and an approximation using an `effective´ shape parameter.