SAR Altimetry Coastal & Open Ocean Performance

The project aims to characterise the expected performance in the open ocean and coastal zone of the Sentinel-3 SAR altimeter product generated by the current processing baseline; and then to test, implement and evaluate improved retrieval methods. The general objectives of the SCOOP are:

• to accurately characterise the expected performance of Sentinel-3 SRAL SAR mode altimeter products over the open ocean and coastal zone.
• to develop and evaluate enhancements to the current baseline Sentinel-3 SRAL SAR data processing schemes, in order to provide improved performance over the open ocean and in the coastal zone.
• to support correct interpretation and application of SRAL SAR L1 products by providing clear technical information on these products and their processing to the user community.
• to provide recommendations for further developments and implementations through a scientific roadmap.

• To characterise the performance of Cryosat-2 SAR mode data in the open ocean using the Sentinel-3 processing baseline applied to Cryosat-2 FBR data
• To carry out investigations on simulated Sentinel-3 data (generated by the Sentinel-3 SPS) in order to evaluate the expected performance of Sentinel-3 over the open ocean
• To develop, test and implement modifications to the processing of the L1B-S product (Stack of Delay Doppler beams) to the L1B product (multi-looked SAR echo) not currently implemented in the Sentinel-3 ground segment (such as zero-padding, multi-looking, antenna pattern compensation, stack beam weighting), and improvements to the implementation of the SAR echo model in the re-tracking of the SAR echo to generate the L2 product. Evaluate the performance of products generated by this modified processing chain and make recommendations with regard to future implementation.
• To carry out a study into the dependency of SAR altimeter data on swell (amplitude, direction and wavelength).
• To propose a solution for a SAR mode Sea State Bias correction for the open ocean. This will take into account, and build on, findings from a parallel study being funded by EUMETSAT (EUMITS ITT No.14/209556 "Jason-CS SAR Mode Sea State Bias Study”), evaluate these findings and propose an approach to be applied to Sentinel-3.

• To characterise the performance of Cryosat-2 SAR mode data in the coastal zone using the Sentinel-3 processing baseline applied to Cryosat-2 FBR data.
• To carry out investigations on simulated Sentinel-3 data (generated by the Sentinel-3 SPS) in order to evaluate the expected performance of Sentinel-3 over the coastal zone.
• To develop, test and implement modifications to the processing of the L1B-S product (Stack of Delay Doppler beams) to the L1B product (multi-looked SAR echo) not currently implemented in the Sentinel-3 ground segment (such as zero-padding, burst weighting window, higher posting rate). Evaluate the performance of products generated by this modified processing chain and make recommendations with regard to future implementation Through a study into SAR stack data exploitation investigate techniques to improve performance close to the coastline by developing techniques to identify and discriminate against the impact of land contamination of the nadir ocean echo.
• To develop, test and implement coastal retrackers for Sentinel-3 SAR and RDSAR data.
• To investigate how the orientation of the ground track with respect to the coastline, and the proximity of the land affect the performance of Sentinel-3 SRAL data.