On an Empirical Model of the Source of Short Wind Waves Based on Radar Observations of Marine Film Slicks

This study is aimed to develop an empirical model of the spectrum of short wind waves in application to a Bragg component of microwave backscattering from the sea surface at moderate incident angles. The radar backscatter in the model is considered as a composition of Bragg (polarized) and non-Bragg (nonpolarized) components. Data of field experiments on radar probing of film slicks carried out with an X-/C-/S-bands two co-polarized radar instrument were used. An empirical expression for an additional source of Bragg centimeter-scale wind waves is proposed, which made it possible to describe the variations of radar backscatter in slicks when the latter are observed in the cross wind direction. The source is described by a power function of a dimensionless parameter—the wave age. It is shown that the additional source can be considered isotropic, as evidenced by good agreement between the measured contrasts in the upwind direction and those calculated using this model.