Uncertainty in the Extreme Waves in the North Atlantic Ocean and Ship Responses

The statistics of the waves in the North Atlantic Ocean have been used as the basis of ship design for decades. Recently, there have been efforts to update the scatter diagram of wave height and period based on the numerical hindcast data combined with AIS data. However, the validation of the extreme wave distribution is problematic due to the lack of observational data. In this study, we have compared the extreme value estimates of the wave height among a 25-year hindcast simulation and satellite-derived products from 1994 to 2018 sampled in the Global Wave Statistics areas 8, 9, 15, and 16. The comparison revealed that both epistemic and aleatory uncertainties affect the detected annual maxima (AM). Nevertheless, the difference in the estimated return period wave heights was within the statistical uncertainty. The locations and timing of the detected events can differ largely between wave hindcast and satellite observation (aleatory), and the AMs vary among satellite products for the same event (epistemic). The Atlantic wave model is based on NOAA Wave Watch III and was forced by NCEP CFSR (TodaiWW3-NK) at a relatively high horizontal (20km) and spectral resolution (10 degrees). Two curated satellite products, Ribal & Young (2019) and the CCI dataset (Dodet et al. 2020) were used.