Simulated Ocean Wave Damping by Summer Sea Ice Cover in the Arctic

Abstract

Wave propagation under the sea ice is an important issue in marine science and engineering. It is of great significance to deepen the understanding of the uncertainty of sea ice effects. In the paper, under the circumstance of simulated summer sea ice in the Arctic, the attenuation process of wave with peak frequency 0.04 Hz moving northward is investigated with the wave model WAVEWATCH III. Five numerical experiments (one with no sea ice effect, two for the effect of dissipation and two for the effect of scattering) were conducted without considering the influences of ocean currents and surface wind. Through analyzing the modeling result, the effects of schemes of dissipation and scattering from sea ice on the damping of ocean swell have been studied. It is shown that, without sea ice influence, the maximum significant wave height of the swell (MSWHS) reduces to about 1/3 of the initial value after the first 12 hours, then to about 1/18 of the initial value after another 36 hours, due to the dispersion of wave energy and water viscosity; with a constant exponential dissipation rate (2.0 x 10-7 m s-1) enforced by sea ice, a reduction of about 0.35 m of MSWHS is added after 12 hours compared to the result with no sea ice effect considered. The added reduction increases in the former 24 hours and then decreases afterwards; with a scheme with dissipation rate dependent on wave frequency and wave number, the damping of ocean wave is stronger and the MSWHS is reduced to less than 0.5 m after 12 hours. Besides, the direction of wave propagation changes, which deserving further study; with the scattering of sea ice considered, the MSWHS is reduced further due to the added conservative redistribution of wave energy. The scheme with foe size considered attenuates the swell stronger compared to the one which enforces isotropic scattering dependent on sea ice concentration. It is dubious that the simulated reduction of MSWHS is weaker when scattering schemes work together with the dissipation scheme compared to the case when only the dissipation scheme is used.