Preliminary Analysis of the GDR-G Data Products of Jason-3 Satellite Altimeter

In early 2025, the Jason-3 satellite orbit was maneuvered from the "interleaved" orbit to a tandem configuration with the Sentinel-6A satellite, concurrent with the upgrade of its Geophysical Data Records (GDR) from Version F to G. To date, six complete cycles of GDR-G products have been released, featuring notable improvements such as the official replacement of the MLE3 retracker with the Adaptive retracker for Sea Surface Height Anomaly (SSHA) calculations. This study aims to evaluate GDR-G performance by analyzing SSHA under eight error correction strategies, using the last six GDR-F cycles and first six GDR-G cycles. Key findings include: significantly reduced SSHA noise in GDR-G compared to GDR-F; relative biases of up to ~4 cm in sea surface height when using different retracking algorithms or correction strategies; and optimal accuracy achieved with the Adaptive retracker combined with 3D sea state bias (SSB) correction. Comparative analysis of Significant Wave Height (SWH), backscattering coefficient (Sigma-0), and wind speed (WS) between MLE4 and Adaptive retrackers revealed anomalies in Adaptive results: clustered SWH outliers near 0 m and 4 m, and WS outliers slightly above 28 m/s. These anomalies, linked to invalid MLE4 retracking results and non-Brownian echo shapes (coastal/inland waters, sea ice), suggest that refining the Adaptive retracker or developing new algorithms could further enhance Jason-3’s observational performance.