In SAR altimetry the Level 1 or Delay-Doppler processing is not unique and shall be very well understood for the retracking to function properly. Both Level 1 and retracking experts must work together to ensure correct results at level 2. Starting from SAMOSA [1] the model has been revisited and modified to make it compatible with any SAR altimeter sensor and Delay-Doppler configuration known till present. These include: CryoSat-2 (both SAR and SARin modes), Sentinel-3 (SAR mode) and Sentinel-6 (Jason-CS) with its interleaved mode (RAW and RMC). Results from CNES CPP have been compared with this solution demonstrating perfect agreement between the numerical solution of CNES and the new analytical formulation at isardSAT inherited from SAMOSA. The new formulation allows for achieving a difference in the order of a few millimeters and equal standard deviation for both sea surface height and significant wave height. Pu has also nicely been compared leading to equal absolute values in terms of mean and standard deviation. It shall be pointed out that this achievement is done without the need of look up tables' solution after retracking as proposed by other teams working with parallel SAR altimetry formulations also inherited from SAMOSA. The nice agreement with CNES CPP numerical solutions of our new formulation is directly achieved from retracking without intermediate processing. On top of this, the new solution has also been applied to Sentinel-6 (Jason-CS) simulated data for verification purposes of the Level 1 Ground Processor Prototype under definition and development at isardSAT (ESA funded) allowing for achieving comparable requirements to those of preceding Jason family missions.

[1] C. Ray, C. Martin-Puig, M-P. Clarizia, G. Ruffini, S. Dinardo, C. Gommenginger, and J. Benveniste. 'SAR Altimeter Backscatterd Waveform Model', approved for publication in IEEE Transactions on Geoscience and Remote Sensing last May 2014.