Current Retrieval from Moving Wave Patterns Seen by Spaceborne SAR

As shown at several conferences in 2018, we have developed a novel ocean wave retrieval technique based on spot-light-mode SAR data, which takes advantage of the long SAR integration time to identify moving wave patterns. In the first step, a complex spotlight-mode image is reprocessed into a series of subaperture images, which reveals motions during a time interval of a few seconds. Then individual Fourier transforms of parts of the subaperture images are computed and combined into three-dimensional wavenumber-frequency spectra, in which most of the spectral energy is found near a dispersion shell given by the theoretical dispersion relation of ocean waves. From this point, techniques known from the analysis of sequences of marine radar images or videos of wave fields can be applied to derive the most likely water depth (in coastal areas) and surface current vector from the shape of the dispersion shell. This conference presentation will focus on first examples of results and discuss the achievable accuracy and effective spatial resolution and the potential of the technique for various applications.