CoAuthors

R. Keith Raney (2kR-LLC, USA); Cristina Martin-Puig (isardSAT, Spain); Laiba Amarouche (Collecte Localisation Satellites, France); Hans Bonekamp (EUMETSAT, Germany)

SAR altimetry over the ocean has attracted considerable attention in the past three years and remarkable progress has been made in a short space of time. The ESA Cryosat-2 mission is the first satellite to provide SAR altimeter data over the ocean, and the data helped to demonstrate the significant benefits of SAR mode for ocean altimetry compared to conventional low-resolution mode (LRM) altimeters. Increased consensus and convergence of the results from different groups using different SAR waveform retrackers indicate there is now a high level of confidence in the ability to retrieve geophysical data from SAR mode altimetry over ocean. Several issues particular to SAR altimetry remain open, specifically the sensitivity to platform mispointing, the lack of a sea state bias model in SAR mode, and the effects of swell and swell direction on SAR waveforms. SAR interleaved mode on Jason-CS is strongly recommended, to enable seamless transformation of SAR mode waveforms into conventional LRM and the means for self-calibration. This would ensure continuity of the high-precision sea level 20-year time series, while at the same time, satisfy the need of the operational community for the reduced noise, finer spatial resolution and improved performance near land afforded by SAR altimetry over then ocean and the coastal zone.