Model sensitivity analysis of scattering-induced attenuation of ice-coupled waves

摘要

The sensitivity of the rate of exponential decay of wave energy through the ice-covered oceans is investigated using a two-dimensional (one horizontal and one depth) linear model. Attenuation in the model results from multiple wave scattering caused by features (irregularities) in the ice cover. The focus of the study is the assimilation of ocean wave/sea ice interactivity-experienced via the attenuation in the model, into an operational ice/ocean forecasting paradigm. Attenuation coefficients are considered, which define the rate of exponential decay as functions of the properties of the ice cover and the incident wave field. It is shown first that wave scattering can be highly sensitive to the values of Young's modulus that are typical of natural sea ice, but that the difference between the values for first-year and multi-year ice is small. Three common ice cover features, namely floes, cracks and pressure ridges, are then examined and compared. Regimes in which particular irregularities are dominant are identified and approximations are derived for the attenuation coefficients produced by each feature. Attenuation produced by rough ice is considered as well, but it is found to be insignificant compared to that due to the three prototype irregularities chosen.