Fabrice Ardhuin, Ifremer

Ocean wave forecasting is based on phase-averaged spectral models. Their accuracy critically depends on the quality of forcing fields, including winds and sea ice, and on the accuracy of the parameterizations for wind-wave evolution (generation, nonlinear evolution and dissipation).

The understanding of wave evolution processes has made important progress in the last decade and recent numerical model developments have shown important error reduction in the significant wave height when compared with satellite altimeter (typically less than 10%). This can be attributed to a better understanding of wave dissipation processes, either for swells or the breaking of locally generated wind-waves. Today the model errors in absolute terms are highest around the marginal ice zones (MIZ).

Figure: Example of IOWAGA hindcast (wwz.ifremer.fr/iowaga) using WAVEWATH III.

Building on our experience with Boltzmann-type equations for wave scattering by bottom topography, our goal is to work from the waves-in-ice models (see WP3 and WP5) to produce scattering cross sections and adapt the numerical techniques already implemented in WAVEWATCH III for wave-bottom scattering. Friction under the ice will also be included in a form similar to the effect of air-sea friction already used for swell dissipation. Remote sensing observations will be used to validate the models in the near field of the ice and on a large scale (see WP4).