POLARIMETRIC SAR IMAGE SIGNATURES OF THE OCEAN AND GULF-STREAM FEATURES

Polarimetric signatures and related polarimetric properties of microwa ve ocean backscatter have been analyzed for both the ambient ocean and for ocean features such as those associated with the Gulf Stream. Int erpretation of the polarimetric signatures for the ocean surface was a ccomplished using a tilted-Bragg theoretical model. This model was use d to calculate the EM fields, to second order, necessary to compute th e full Stokes matrix and, ultimately, the polarimetric signature. The polarimetric studies led to a technique for potentially improving the visibility of all azimuthally traveling waves in real-aperture radar ( RAR) images and, very long waves in synthetic-aperture radar (SAR) ima ges. This technique utilizes linear polarization signatures to maximiz e the instrument sensitivity to azimuthally traveling waves. Wave tilt s create a modulation of the cell polarization orientation which, in t urn, modulates the backscatter. Critical to the success of this techni que are the properties that ocean polarimetric signatures are sharply peaked (i.e., returns are highly polarized). The polarimetric contribu tion to the overall modulation transfer function has also been evaluat ed.