Role of sea ice on winter wave power and its interannual variability in the Sea of Okhotsk: Natural breakwater modified by surface wind changes

Abstract

This study conducted three wave model simulations with data collected over 40-year time frame. The simulations were based on the reanalysis surface wind and the satellite sea ice products in the Sea of Okhotsk (SO). To investigate the quantitative impact of sea ice on the winter wave power (Pw) and its interannual variability, wave model simulations were conducted using daily sea ice, climatological sea ice, and no sea ice. The model results with the daily sea ice corresponded well with buoy observations. The results showed that sea ice significantly reduced the climatological mean and the interannual variability (standard deviation) of Pw by approximately 50 % (> 50 % in the northwestern area) over the SO during late winter (February–March). Additionally, the negative feedback process of Pw by sea ice triggered by the northwesterly wind was shown. The prevailing northwesterly wind increased the Pw in November, whereas sea ice increased in the following winter through intensive upward surface heat loss owing to the prevailing wind and relatively cold and dry air it transports. As a result, the increased sea ice led to direct wave attenuation and the weakening of surface wind, which reduced the Pw during the early and late winters (December–March).