Effects of Ice-induced Wave Attenuation on Surface Waves in the Arctic Ocean: An Application of FVCOM-SWAVE

The Arctic Ocean has been experiencing a rapid decrease in sea ice area and increase in the marginal ice zone (MIZ) in summer during the latter half of the 20th century. To investigate the role of ice-wave interaction in ice drift, wave attenuation and wave-induced ice breaking, we implemented ice-wave interaction dynamics into the unstructured- grid surface wave model (SWAVE) and coupled it with the Arctic Ocean FVCOM (AO-FVCOM) to establish a fully ice-wave-current unstructured-grid finite-volume model for Arctic Ocean research. In configuring SWAVE for global and basin-scale Arctic Ocean applications with inclusion of the North Pole in the spherical coordinate system, three actions were taken: one was to avoid the so-called invalid scalar assumption at high latitudes; second was to solve the singularity issue at the North Pole; and the third was to formulate a parameterization for wave-ice interactions. Process-oriented experiments were conducted to examine the influence of ice-induced wave attenuation on the wind sea and swell waves propagating into the marginal ice zone (MIZ). The model-simulated significant wave heights and peak periods were compared with available buoy measurements in the Arctic. We found that results were improved when the ice-induced attenuation and the blocking effect of the ice on the surface forcing mechanisms are included in the model system. The model results also suggested that the ice-induced wave attenuation played a key role in dissipation of windsea and swell waves in the MIZ. Ignoring this process can lead to biases in simulations of dynamical features of both the wind sea and swell. An empirical method was used to estimate the wave-induced ice breaking, and the results suggested that when the ice concentration was less than 0.6 the wave-induced internal ice strain could cause ice breaking as waves penetrated into the MIZ.