Application of MA-ATI SAR for Estimating the Direction of Moving Water Surface Currents in Pi-SAR2 Images

A multiaperture along-track interferometric synthetic aperture radar (MA-ATI SAR) theory was proposed to obtain velocity vectors of moving objects. This theory utilizes two antennas to estimate two velocity components (aft- and fore-looking directions) by multi/sublook processing. The moving direction can then be calculated by the two velocity components. Combining it with the conventional range velocity estimation, the velocity vector can be estimated. In order to validate its methodology, the present study applies MA-ATI SAR to airborne polarimetric interfereometric SAR-2 (Pi-SAR2) for estimating the directions of moving water surface currents of rivers. The results were in good agreement with the true moving directions. The estimated accuracy showed the direction error of approximately 20° for the three cases out of four. One case showed the higher error, since there may be complicated flow patterns. The findings of this study have implications for the applicability of the MA-ATI method to an airborne SAR system.