Wave Steepness and Rogue Waves in the Changing Climate in the North Atlantic

Wave steepness is an important parameter not only for design and operations of marine structures but also for statistics of surface elevation as well as occurrence of rogue waves. The present study investigates potential changes of wave steepness in the future wave climate in the North Atlantic. The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) uses four scenarios for future greenhouse gas concentrations in the atmosphere called Representative Concentration Pathways (RCP). Two of these scenarios with radiative forcing of 4.5 and 8.5 W/m² by the end of the 21st century have been selected to project wave conditions in the North Atlantic. The analysis includes total sea, wind sea and swell. Changes of wave steepness for these wave systems are shown and compared with wave steepness derived from historical data. Long-term probability description of wave steepness variations is proposed. Consequences of changes in wave steepness for statistics of surface elevation and generation of rogue waves are demonstrated. Uncertainties associated with wave steepness projections are discussed.