CRYOSAT-2 SAR Mode Over Ocean: Processing Methods, Global Quality Assessment and Benefits
Boy, Francois1; Picot, Nicolas1; Desjonqueres, Jean-Damien1; Moreau, Thomas2; Labroue, Sylvie2; Thibaut, Pierre2

In the frame of the Sentinel3 project, CNES is involved in the overall topography payload product quality. Sentinel3 embarks an altimeter including a conventional LRM mode and a SAR mode. The SAR mode propose enhanced performances compared to the conventional mode, thanks to a reduced along track resolution (from 10km to 300m) and a lower measurements noise level. However, while there is a long experience of LRM data processing, SAR nadir looking data are new and will need extensive prototype development and an in depth validation. To contribute to those analysis, CNES took the opportunity of the availabilty of CRYOSAT-2 SAR data over ocean and started, two years ago, the development of a Cryosat processing Protoype to generate Level2 product including Sea Level Anomaly and Significant WaveHeigh information from both LRM L1B and SAR FBR products. In the frame of the ESA living planet Symposium, we propose to present for the first time, a global data quality assessment of SAR data over ocean using more than six months of SAR data. We will present the cross comparison between SAR and RDSAR (LRM reference built from SAR measurements) SLA and SWH estimates, the data quality continuity when the altimeter switches from one mode to the other and also on SLA spectrum analysis. In addition, the SAR processing techniques and the algorithms developped on CNES side will be recalled and the improvments from 2012 OSTST and AGU meetings will be summarized. We will also present an overview of the PIs feedbacks obtained on the level2 and level3 CNES SAR products.