Study of integration time effects on coherent radar imagery of the sea surface

Remote sensing of the ocean surface using interferometric SAR techniques is of significant interest due to the potential for synoptic measurement of ocean wave and surface current patterns. INSARs use the phase difference between colocated SAR images separated by a small time lag to infer surface radial velocities, and hence wave orbital velocities and currents. The quality of such measurements is affected both by the integration time used In forming SAR images and by the much smaller time lag separating the images. In March 1994, the FOPAIR imaging radar obtained near-instantaneous imagery of ocean surface backscatter and Doppler velocity at 64 frames per second. The authors investigate explicitly sea surface motion effects on INSAR imagery by subsampling the radar´s data stream. Through sub-sampling, longer coherent integration times are synthesized yielding INSAR-like images which may be compared to coincident high-speed radar images. Through this analysis, the effects of integration time on image quality and current measurements are revealed