Abstract
We review experimental evidence for the nonlinearity of sea clutter
and the role of the z-parameter or Mann-Whitney rank-sum statistic in
quantifying this nonlinear behavior in the context of a hybrid AM/FM model
for sea clutter, viewed as a cyclostationary process. An independent theoretical
derivation of the stochastic dynamics of radar scattering in a sea clutter
environment, in terms of a pair of coupled stochastic differential equations for
the received envelope and radar cross-section (RCS), enables the identification
of nonlinearity in terms of the shape parameter for the RCS. We are led
to conclude that, from both experimental and theoretical points of view, the
dynamics of sea clutter are nonlinear with a consistent degree of nonlinearity
that is determined by the sea state.