SAR Image Modulation by Ocean Current Variations Induced by Underwater

Abstract

This paper presents the quantitative analyses of radar backscatter from sea surface in the presence of varying currents associated with internal waves and bottom topography. The waveheight spectrum of sea surface perturbed by slowly-varying surface current is computed using the first-order solution of the action balance equation which describes the hydrodynamic interaction between the surface waves and varying current. The backscatter radar cross section (RCS) is then computed using the small perturbation method (SPM) and the results are compared with the RADARSAT-1 images of internal waves in the East/Japan Sea, and also with the ENVISAT-ASAR image modulated by varying surface currentsin the shallow waters of Yellow Sea in the west coast of the Korean Peninsula. On a whole the agreement is fairly good,but some discrepancy has been observed and the reasons are discussed. surface current is computed using the first-order solution of the action balance equation which describes the hydrodynamic interaction between the surface waves and varying current. The backscatter radar cross section (RCS) is then computed using the small perturbation method (SPM) and the results are compared with the RADARSAT-1 images of internal waves in the East/Japan Sea, and also with the ENVISAT-ASAR image modulated by varying surface currentsin the shallow waters of Yellow Sea in the west coast of the Korean Peninsula. On a whole the agreement is fairly good,but some discrepancy has been observed and the reasons are discussed.