Study on the Doppler shift and the spectrum widening of the scattered echoes from the 2-D rough sea surface

Abstract

Based on the 2-D ocean-like surface of linear model and the first-order small slope approximation，the characteristic of Doppler shift for different order Doppler spectra of scattered echoes is investigated and the formula of Doppler shift is derived. Comparing with the conventional formula of Doppler shift，the influence of the wind speed and the orbit motion of the sea wave in large scale is considered in our result. By employing the two-scale model of rough surface and physical mechanism of Doppler shift，a formula of the spectrum widening for the scattered field from the oceanic surface is also presented. The numerical results evaluated by the formulae in this study are compared with the simulated and the measured data，the dependence of the Doppler shift and the spectrum widening on the parameters，such as the wind speed，the frequency of the incident wave and the incident angle, etc. are discussed. It is found that the formulae obtained in this research can be used to predict the Doppler shift and the spectrum widening.