Alejandro Egido (GST/NOAA, United States); Luciana Fenoglio (University of Bonn, Germany); Walter Smith (NOAA, United States)

For more than ten years, Synthetic Aperture Radar (SAR) altimetry has contributed to a better understanding of sea surface related parameters such as sea surface height (SSH), significant wave height (SWH) and windspeed. However, compared to conventional altimetry (CA) data an inconsistency with respect to SWH estimates is observed. We suggest to solve this issue by introducing an additional geophysical parameter sigmav describing an along-track blurring effect caused by vertical wave particle velocities. As this parameter effects a SAR waveform in a very similar way than SWH it is necessary to use the whole SAR stack as a retracking input. Otherwise, the retracker will not be able to distinguish between SWH and sigmav.

This study shall give an overview about how 2D SAR retracking can be achieved in a – to our best knowledge – correct and efficient manner. We will discuss stack processing choices, starting at Full Bit Rate (FBR) data and retracking choices on the example of CryoSat-2, Sentinel-3A and Sentinel-3B.

The performance of the retrieved geophysical parameters will be visualized in this study with respect to the ERA5 wave model and in-situ-data located in the northeast Atlantic region.