Statistical model representing storm avoidance by merchant ships in the North Atlantic Ocean

Abstract The ocean waves in the North Atlantic Ocean are internationally recognized to represent a wave climate suitable for the design of merchant ships. However, the accumulated knowledge from the past indicates that the encountered sea states are less severe than the Standard Wave Data recommended by the International Association of Classification Society. In this study, we propose a statistical model representing storm avoidance by ships and apply it to a newly computed 25-year wave hindcast (TodaiWW3-NK) in the North Atlantic Ocean. We derive the 25-year statistics of waves encountered by merchant ships. The statistical model relates the storm intensity and the distance of the ship from the storm center and derives from the 2 years and 11 months of ship position records based on Automatic Identification System (AIS) and the hindcast wave data. The estimated 25-year exceedance probability of significant wave height in the North Atlantic Ocean agrees well with that of the waves encountered along the shipping route, thereby demonstrating the validity of the suggested storm avoidance model. The most significant uncertainty of the estimate originates from the choice of a wave model, as shown by comparison with the estimation based on other hindcast products (ERA5 and IOWAGA).