Alice Dalphinet (Meteo France, France); Fabrice Collard (Ocean Data Lab, France); Daniele Hauser (LATMOS/CNRS, France); Bertrand Chapron (IFREMER, France)

Ocean waves in the marginal ice zone (MIZ) play an important role in the mixing at the opper oceanic layers, particularly in austral summer seasons when the impact of waves on ocean circulation is more pronounced. This work consists in using the assimilation of directional wave observations from SWIM instrument of CFOSAT to improve sea state forecasting in the marginal ice zone and also to develop a wave/ice interaction source term able to well capture the attenuation of wave energy and frequency spreading in these areas of interest like the Weddell Sea. Several austral summer seasons from 2020 to 2022 have been considered for this study. We performed MFWAM wave model simulations of 10 km grid size with improved ice fraction forcings such as those provided from AMSR-2 radiometer (University of Bremen) and also CFOSAT ice fraction products. In this framework we evaluated the impact of ice fraction forcing on the fetch conditions for the generation of wind waves.
We have identified areas of wave passage under ice floe to analyze the variability of waves in direction and frequency. The validation of the results is mostly based on significant wave height from altimeters like Sentinel-3 or Cryosat-2, and also opportunity field compaign.
In addition, we have examined the impact of wave attenuation on a 1-D ocean mixing layer model in the Weddell Sea. Discussions of these results will be presented in the final paper.