A physical model of wave attenuation in pancake ice

A physical model is discussed that mimics the interaction between ocean waves and a multitude of loose pancake ice floes, which form the outer edge of the Arctic and Antarctic marginal ice zones during winter sea ice formation. The pancakes were modeled by using ice cubes with different concentrations, while waves were generated mechanically. The ice cubes had a dimension of a few centimeters, which was two orders of magnitude smaller than the dominant wavelength. Experiments consisted of tracking the propagation of regular and irregular wave fields along the flume as they crossed the ice cover to measure the rate of ice-induced wave attenuation. Results indicate that wave attenuation increases with ice concentration with only 30% of energy allowed to pass through high-density covers. Wave energy is attenuated across the entire spectral domain and is strongest at high frequencies. This results in a downshift of the spectral peak.