A fresh look at how ocean waves and sea ice interact

Because of their capacity to alter floe size distribution and concentration and consequently to influence atmosphere-ocean fluxes, there is a compelling justification and demand to include waves in ice/ocean models and earth system models. Similarly, global wave forecasting models like WAVEWATCH III (R) need better parametrizations to capture the effects of a sea ice cover such as the marginal ice zone on incoming wave energy. Most parametrizations of wave propagation in sea ice assume without question that the frequency-dependent attenuation which is observed to occur with distance x travelled is exponential, i.e. A =A(0) e(-alpha x). This is the solution of the simple first-order linear ordinary differential equation dA/dx = -alpha A, which follows from an Airy wave mode ansatz A exp i(kx +/- omega t). Yet, in point of fact, it now appears that exponential decay may not be observed consistently and a more general equation of the type dA/dx = -alpha A(n) is proposed to allow for a broader range of attenuation behaviours should this be necessary to fit data. This article is part of the theme issue 'Modelling of sea-ice phenomena'.