Effects of Superharmonic Generation on Wave Interactions with a Sea Ice Sheet

In the marginal ice zone (MIZ), ocean wave and sea ice processes are strongly coupled since waves cause ice breakup and the ice attenuates the incident wavefield. Determining the underlying mechanisms of this feedback loop is important in understanding the evolution of the ice pack as well as improving sea ice forecasting. While wave-ice coupling has been studied using linear wave and structural models, few works address nonlinear wave-wave interactions which are important since many key mechanisms are strong functions of wave frequency. We use a modified high-order spectral method, complemented by perturbation analysis, to determine the nonlinear response of a finite ice sheet to waves propagating from open water. We demonstrate that, due to nonlinear energy transfer to shorter waves, (a) the maximum strain in the ice sheet can as much as double the linear prediction under certain conditions and (b) the reflection of wave energy by the ice sheet is a strong function of the nonlinear interaction length scale and can significantly exceed the linear result.