Oceanic Variables extracted from Along-Track Interferometric SAR data
Seoul National University,
Sil-Rim Dong, Kwan-Ak Gu,
Korea, Republic of
The Synthetic Aperture Radar (SAR) data contain the greatest amount of information among various microwave techniques developed for measuring ocean variables from aircraft or satellites. They have the potential of measuring wavelength, wave direction and wave height of the ocean waves. But, it is difficult to retrieve ocean wave heights and surface current from conventional SAR data, since the imaging mechanism of ocean waves by the SAR is determined by the three basic modulation processes arise through the tilt modulation, hydrodynamic modulation and velocity bunching, which are poorly known functions. Along- Track Interferometric (ATI) SAR systems can directly detect the Doppler shift associated with each pixel of a SAR image and have been used to estimate wave fields and surface currents. However, the Doppler shift is not simply proportional to the component of the mean surface current. It includes also contributions associated with the phase velocity of the Bragg waves and orbital motions of all ocean waves that are longer than Bragg waves. We have developed a method for extracting the surface current vector from multiple-frequency (L- & C-band) ATI SAR data, and have generated surface wave height.