INTERPRETATION OF SAR IMAGE MODULATION BY THE INTERACTION OF CURRENT AND BOTTOM TOPOGRAPHY IN GYEONGGI BAY WITH MICROWAVE SCATTERING MODELS

Abstract

The effect of the interaction between surface currents and bottom topography to the radar cross section (RCS) is investigated using theoretical and numerical scattering models and synthetic aperture radar (SAR) data. First, the ocean waveheight spectrum perturbed by a varying surface current is computed under the wind condition at the time of SAR data acquisition. The surface current data are extracted from the tidal current models. The RCS modulations are then computed using the small perturbation method (SPM) and the numerical scattering model based on the method of moments (MoM) with undulated surface height profiles simulated from the perturbed wave spectrum using the Monte-Carlo method. The RCS modulation relative to the RCS from the surrounding ambient sea surface is used to evaluate the two scattering models, and comparison of the results with X- and C-band data shows that the SPM underestimates the SAR data and that the MoM yields better agreement with the error of 11% in the relative RCS peak value and the peak displacement of 750 m with respect to the observed position. Although there still exist some discrepancy in the RCS modulation, the present results show the potential of the numerical approach based on the MoM and Monte Carlo simulation for analysing the interaction between ocean current and bottom topography.