Spectral Modeling of Ice-Induced Wave Decay

Three dissipative (two viscoelastic and one viscous) ice models are implemented in the spectral wave model WAVEWATCH III to estimate the ice-induced wave attenuation rate. These models are then explored and intercompared through hindcasts of two field cases: one in the autumn Beaufort Sea in 2015 and the other in the Antarctic marginal ice zone (MIZ) in 2012. The capability of these dissipative models, along with their limitations and applicability to operational forecasts, are analyzed and discussed. The sensitivity of the simulated wave height to different source terms-the ice-induced wave decay S-ice and other physical processes S-other (e.g., wind input, nonlinear four-wave interactions)-is also investigated. For the Antarctic MIZ experiment, S-other is found to be remarkably less than S-ice and thus contributes little to the simulated significant wave height H-s. The saturation of dH(s)/dx at large wave heights in this case, as reported by a previous study, is well reproduced by the three dissipative ice models with or without the utilization of S-other in the ice-infested seas. A clear downward trend in the peak frequency f(p) is found as H-s increases. As f(p) decreases, the dominant wave components of a wave spectrum will experience reduced damping by sea ice, and finally result in the flattening of dH(s)/dx for H-s. 3m in this specific case. Nonetheless, S-other should not be disregarded within a more general modeling perspective, as our simulations suggest Sother could be comparable to S-ice in the Beaufort Sea case where wave and ice conditions are remarkably different.