Author(s): Fabien Montiel; Vernon A. Squire; Luke G. Bennetts
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Abstract: The single ice edge band model of Montiel et al. (2014) is extended to depict the progression of a prescribed directional wave spectrum as it enters and traverses a marginal ice zone (MIZ) composed of ice floes of random sizes and locations present at some concentration. This is achieved by considering the MIZ to be assembled from many contiguous parallel ice bands. Although the wave energy entering each constituent band is multiply-scattered by the elemental ice floes that make up the band, the complicated interactions that arise can be consolidated into continuous sums of plane waves travelling at all possible angles which constitute the reflected and transmitted directional spectra. The latter sum passes into the next band in sequence, which allows the entire MIZ to be modelled expediently. Comparisons with field data (Wadhams et al., 1986) indicate good qualitative agreement for single bands of ice, with improved reconciliation as ice concentration is increased towards the usually high concentration values observed within ice edge bands in Nature. As directional seas travel through MIZs, they are found theoretically to broaden in their directional spread with the degree of broadening increasing with penetration; short waves quickly become directionally isotropic, while longer waves remain collimated for greater distances into the pack ice. This is compatible with Wadhams et al. (1986). The waves are preferentially attenuated en route, as well, again with the short period end of the spectrum being affected first. The overarching motivation of this work is the optimum assimilation of wave-ice interactions into ice/ocean models and oceanic general circulation models.
Year: 2014