Uncertainty in ocean wave estimate in the Arctic Ocean

The Arctic sea ice is retreating at an accelerating rate and ocean waves in the emerging open waters are increasing. While the possible positive feedback of wave-ice-breakup is an environmental concern, the widely open ice-free waters are providing economic opportunities to the Arctic Circle communities. The need for accurate prediction of ocean waves in the open waters, coastal region, and in the Marginal Ice Zone is imminent. The Japanese R/V Mirai has conducted three expeditions in the Arctic Ocean in 2016 September and October 2018 November, and 2019 October in the Beaufort Sea and the Chukchi Sea. Through the collected knowledge based on wave buoy observations and modeling, we have identified that the largest sources of uncertainties of wave estimates are not necessarily the wave-ice interaction physics, but the uncertainty in the wind and sea-ice forcing. By analyzing the reanalysis wave field, we have shown that the extreme waves in the open waters are increasing as the chances of Arctic Storms generating ocean waves increase with the enlarged open water area. For those extreme events, the location of the ice-edge is not necessarily important as the storm size is smaller than the open water area. In such a case, the source of uncertainty is the reanalysis wind field. On the other hand, waves near the MIZ is highly uncertain, not because of inaccurate wave-ice interaction physics but is because of the uncertainty in the sea ice concentration. The satellite-derived S.I.C. estimates are highly variable depending on the sensors and analysis algorithms, and the associated uncertainty of ocean wave model-estimates is larger than the uncertainty related to the wave-ice interaction physics.