Connecting Wave Intensity in Ice and Open Water within the Marginal Ice Zone

The marginal ice zone (MIZ) is the region of fragmented ice floes at the interface between open ocean and consolidated sea ice. Understanding wave propagation through the MIZ is necessary to improve sea ice forecasts for maritime operations and to capture wave-ice feedbacks in Earth system models. Radiative transfer theory is commonly used to model wave attenuation in the open water between floes; however, quantifying wave intensity within ice sheets remains challenging due to their variable geometry and material properties. Relating the in-ice wave intensity to that in the surrounding open water is important to determine when ice will fracture and to parametrize in-ice dissipative processes. While the wave response of an ice sheet to a unidirectional wavefield is generally a function of ice geometry, field observations show that short waves propagating within the MIZ quickly become isotropic due to multiple scattering. By assuming an isotropic wavefield, we derive a simple expression, which is independent of ice geometry, relating the wave intensity in ice to that in open water. We validate this theoretical result with direct computations of wave-ice interactions for various simple geometries.