A model is reported for wave propagation through a marginal ice zone (MIZ) based upon the finite floe solution of Meylan and Squire (1993a, b, 1994). It is shown first that an approximate solution which neglects interaction between adjacent ice floes is amply precise in most circumstances. Then the propagation of waves through an array of discrete, non-colliding floes based on the addition of energy is considered, assuming that floe lengths are Rayleigh distributed. It is found under these conditions that an MIZ is analogous to a low-pass filter to incoming ocean waves, with filter characteristics a function of average floe length, floe thickness and the number of floes present.
Ocean wave propagation through ice-infested seas is a topical area of research because of its relevance to the navigation of vessels within the world's MIZs and the construction and maintenance of offshore structures in ice fields. Both are practical engineering issues which require timely action- wave spectral densities will evolve spatially as they travel though an MIZ, thereby affecting wave forces and forces due to the momentum of discrete floes locally. Field measurements have been made of wave propagation through various ice covers and the concomitant change in the spectrum of wave energy With penetration has been monitored. Wadhams et al (1988), for example, report results for a number of experiments carried out by the Scott Polar Research Institute between 1978 and 1983 in the MIZs of the Greenland and Bering Seas. In this programme wave energy was measured at a series of locations in the ice cover while the floe size distribution was determined by aerial photography. In general it was found that the wave energy decayed exponentially and that the attenuation coefficient decreased with increasing wave period. Similar results were described by Squire and Moore (1980) for the Bering Sea. Wadhams et al. (1986) reported measurements made during MIZEX-84 In the Greenland Sea.