Lionel Zawadski (CNES, France)

After the launch of Sentinel-6B, new wave data are available to enhance the density of Significant Wave Height (SWH) across all ocean basins. The objective of this study is to assess the quality of the wave heights provided by the Sentinel-6B Level 2 Low Resolution (LR) products and the impact of assimilating these data on wave forecasting. Data from cycles 4, 5, 6, 7, and 8 were used. A quality control procedure was developed to filter corrupted wave data. Simulations were carried out using the operational wave model MFWAM in a global configuration with a 20 km resolution, both with and without the assimilation of Sentinel-6B wave heights. The simulations were forced by winds and ice fraction from the IFS-ECMWF atmospheric system.
The results show a significant impact of assimilating Sentinel-6B wave heights on wave forecasting, with a notable reduction in the scatter index of SWH, with an average of 15%. Comparison with the assimilation of Sentinel-6A data during the tandem phase shows consistent performance, with almost similar biases and scatter indices of SWH. In this study, we also present the results of assimilating Sentinel-6B wave heights in comparison with drifting wave buoys data. Particular attention is given to the performance of the assimilation for high wave heights. Further discussions and conclusions will be commented in the final presentation.