Using the CCRS along track InSAR to measure and interpret ocean surface currents

In 1993 the Canada Centre for Remote Sensing modified its CV-580 C(HH)-band airborne cross-track interferometric SAR (InSAR) to operate in an along track interferometric mode using a switchable microstrip antenna mounted on the right side of the aircraft. Subsequently this instrument has been used to measure ocean surface velocities in missions over the Bay of Fundy, the Grand Banks, and in Active Pass. The resulting velocity images can be used to provide information about surface current vectors, bottom topography, or ocean wave heave spectra. Ground truthing of the bottom topography was provided during a Bay of Fundy mission by a side scan sonar on the Canadian Hydrographic Services vessel, "NSC Frederick G. Creed", whereas validation of the surface current measurements has come mostly from current models. The results of these experiments suggest that, under the right conditions, the CCRS along track InSAR can produce a self-consistent surface current vector map and can detect bottom topography changes of 3 to 4 m at depths up to 30 or 40 m.