This paper is concerned with estimation of the tri-variate probability density function (PDF) of the sea surface elevation and slope components for use in studies of radar sea scattering. The effects of Monte Carlo simulations of linear and nonlinear waves on radar backscatter from low grazing angles are compared to the results obtained from the tri-variate PDF. Simplified examples that eliminate one slope component are analyzed to show some of the differences between linear and nonlinear wave properties. The tri-variate PDF for the linear case is given in the form of a multivariate normal distribution whose covariance matrix is calculated from the wavenumber-direction spectrum. An extension to the nonlinear case is described. The results are consistent with present knowledge of nonlinear ocean wave dynamics and exhibit such well-known features as sharp crestedness and elevation PDF skewness. The second way to describe the wavy surface is to Monte Carlo representative surfaces and determine those portions illuminated by the radar for selected grazing angles. The stochastically generated and empirical PDFs are consistent with each other. Nonlinearization of the sea surface does not appreciably alter the wave spectrum but has a large effect on the shadowing that severely affects the sea scatter of a radar beam incident at a small grazing angle.
Stochastic simulation of ocean waves and their effect on microwave scattering
1999
12 Seiten, 20 Quellen
Aufsatz (Konferenz)
Englisch
Absorption and Scattering of Electromagnetic Waves by Microwave Streamer
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