Multibaseline ATI-SAR for robust ocean surface velocity estimation in presence of bimodal Doppler spectrum

Advanced multibaseline along-track synthetic aperture radar interferometry (ATI-SAR) offers the new functionality of resolution in the Doppler shift domain. This paper investigates the possibility of exploiting multibaseline Doppler resolution capability to produce estimates of ocean surface velocity that are robust to possible bimodal spectra of speckle, arising when both advancing and receding Bragg waves contribute to radar scattering. Bias and inflated variance for unexpected dual Bragg components in conventional ATI are analyzed. Four methods are proposed and analyzed to process multibaseline data for robust estimation, based on Fourier transform or on modern adaptive Capon´s filtering. Simulated results show that this multibaseline technique can be effective to produce accurate estimates in the presence of bimodal spectra