MULTI-APERTURE ALONG-TRACK INTERFEROMETRIC SAR FOR ESTIMATING VELOCITY VECTOR OF OCEAN CURRENTS

The present paper describes a theory of estimating velocity vector of ocean currents using the conventional along-track interferometric synthetic aperture radar (ATI SAR or AT-InSAR) data. In the proposed system, termed as multiaperture along-track interferometric (MA-ATI) SAR, the range velocity vector is computed from the conventional ATI SAR data. For the direction of velocity vector, multi-/sublook processing in the azimuth direction is applied to each raw data acquired by the fore and aft antennas, yielding four complex sub-images, two of which are forward-looking and the other two are backward-looking. Two interferograms of different azimuth look directions are then computed, and the direction of ocean currents can be measured either from the velocity components of different look directions, or directly from the interferometric phases. With the direction of motion and range velocity computed by the MA-AIT system, the velocity vectors of ocean currents and also moving hard targets on land and sea can be estimated.