Jason-1 Global Statistical Evaluation and Performance Assessment: Calibration and Cross-Calibration Results

Since Jason-1 launch, extensive validation of Jason-1 data and cross-calibration relative to TOPEX/Poseidon (T/P) have been performed by the CLS validation team within the CNES Jason-1 project. These validation activities are routinely operated as part of the Jason-1 ground segment, and often lead to in-depth studies to understand all validation conclusions. This article presents the main results in terms of Jason-1 data quality: verification of data availability and validity, monitoring of the most relevant altimeter and radiometer parameters, and assessment of the Jason-1 altimeter system performances. From a global statistical analysis of more than two years of Jason-1 GDR data, results for all components of the altimeter measurement are derived in terms of bias, trend, and precision. This work also represents a contribution to the estimation of the Jason-1 error budget. Thorough studies have been more focused on specific issues in relation to data quality. This is the case for the analysis of the high frequency content of the Jason-1 data and its impact on the T/P to Jason-1 comparison. From the results presented here, it is demonstrated that the Jason-1 mission fulfils the requirements of high precision altimetry. In particular, it allows continuing the observation of the Mean Sea Level (MSL) variations at the same accuracy as T/P, which was one of the challenges of the Jason-1 mission. Potential improvements and open issues are also identified, with the objective of still making progress in terms of altimeter data quality.